Compositor works with X11. Somewhat

samples/ControlCatalog.NetCore/Program.cs

@@ -111,6 +111,7 @@ namespace ControlCatalog.NetCore
                     EnableMultiTouch = true,
                     UseDBusMenu = true,
                     EnableIme = true,
+                    UseCompositor = true
                 })
                 .With(new Win32PlatformOptions
                 {

src/Avalonia.Base/Avalonia.Base.csproj

@@ -3,10 +3,13 @@
     <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
     <AssemblyName>Avalonia.Base</AssemblyName>
     <RootNamespace>Avalonia</RootNamespace>
-    <AllowUnsafeBlocks>True</AllowUnsafeBlocks>    
+    <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
+    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
+    <CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)\GeneratedFiles</CompilerGeneratedFilesOutputPath>
   </PropertyGroup>
   <ItemGroup>
     <EmbeddedResource Include="Assets\*.trie" />
+    <AdditionalFiles Include="composition-schema.xml" />
   </ItemGroup>
   <Import Project="..\..\build\Base.props" />
   <Import Project="..\..\build\Binding.props" />

src/Avalonia.Base/Collections/IAvaloniaReadOnlyList.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;

src/Avalonia.Base/Collections/Pooled/PooledList.cs

@@ -1434,7 +1434,7 @@ namespace Avalonia.Collections.Pooled
         /// <summary>
         /// Returns the internal buffers to the ArrayPool.
         /// </summary>
-        public void Dispose()
+        public virtual void Dispose()
         {
             ReturnArray();
             _size = 0;

src/Avalonia.Base/Matrix.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Globalization;
+using System.Numerics;
 using Avalonia.Utilities;
 
 namespace Avalonia
@@ -106,6 +107,36 @@ namespace Avalonia
                 (value1._m31 * value2.M12) + (value1._m32 * value2.M22) + value2._m32);
         }
 
+        public static Matrix operator +(Matrix value1, Matrix value2)
+        {
+            return new Matrix(value1.M11 + value2.M11,
+                value1.M12 + value2.M12,
+                value1.M21 + value2.M21,
+                value1.M22 + value2.M22,
+                value1.M31 + value2.M31,
+                value1.M32 + value2.M32);
+        }
+        
+        public static Matrix operator -(Matrix value1, Matrix value2)
+        {
+            return new Matrix(value1.M11 - value2.M11,
+                value1.M12 - value2.M12,
+                value1.M21 - value2.M21,
+                value1.M22 - value2.M22,
+                value1.M31 - value2.M31,
+                value1.M32 - value2.M32);
+        }
+        
+        public static Matrix operator *(Matrix value1, double value2)
+        {
+            return new Matrix(value1.M11 * value2,
+                value1.M12 * value2,
+                value1.M21 * value2,
+                value1.M22 * value2,
+                value1.M31 * value2,
+                value1.M32 * value2);
+        }
+
         /// <summary>
         /// Negates the given matrix by multiplying all values by -1.
         /// </summary>
@@ -427,6 +458,14 @@ namespace Avalonia
             return true;
         }
 
+#if !BUILDTASK
+        public static implicit operator Matrix4x4(Matrix m)
+        {
+            return new Matrix4x4(new Matrix3x2((float)m._m11, (float)m._m12, (float)m._m21, (float)m._m22,
+                (float)m._m31, (float)m._m32));
+        }
+#endif
+        
         public struct Decomposed
         {
             public Vector Translate;

src/Avalonia.Base/Rendering/Composition/Animations/AnimatedValueStore.cs

@@ -0,0 +1,40 @@
+using Avalonia.Rendering.Composition.Expressions;
+using Avalonia.Rendering.Composition.Server;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    internal struct AnimatedValueStore<T> where T : struct
+    {
+        private T _direct;
+        private IAnimationInstance _animation;
+        private T? _lastAnimated;
+
+        public T Direct => _direct;
+
+        public T GetAnimated(ServerCompositor compositor)
+        {
+            if (_animation == null)
+                return _direct;
+            var v = _animation.Evaluate(compositor.ServerNow, ExpressionVariant.Create(_direct))
+                .CastOrDefault<T>();
+            _lastAnimated = v;
+            return v;
+        }
+
+        private T LastAnimated => _animation != null ? _lastAnimated ?? _direct : _direct;
+
+        public bool IsAnimation => _animation != null;
+
+        public void SetAnimation(ChangeSet cs, IAnimationInstance animation)
+        {
+            _animation = animation;
+            _animation.Start(cs.Batch.CommitedAt, ExpressionVariant.Create(LastAnimated));
+        }
+
+        public static implicit operator AnimatedValueStore<T>(T value) => new AnimatedValueStore<T>()
+        {
+            _direct = value
+        };
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/CompositionAnimation.cs

@@ -0,0 +1,63 @@
+// ReSharper disable InconsistentNaming
+// ReSharper disable CheckNamespace
+
+using System;
+using System.Collections.Generic;
+using System.Numerics;
+using Avalonia.Rendering.Composition.Expressions;
+using Avalonia.Rendering.Composition.Server;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+      public abstract class CompositionAnimation : CompositionObject,  ICompositionAnimationBase
+      {
+          private readonly CompositionPropertySet _propertySet;
+          internal CompositionAnimation(Compositor compositor) : base(compositor, null!)
+          {
+              _propertySet = new CompositionPropertySet(compositor);
+          }
+
+          private protected override IChangeSetPool ChangeSetPool => throw new InvalidOperationException();
+
+          public void ClearAllParameters() => _propertySet.ClearAll();
+
+          public void ClearParameter(string key) => _propertySet.Clear(key);
+
+          void SetVariant(string key, ExpressionVariant value) => _propertySet.Set(key, value);
+          
+          public void SetColorParameter(string key, Avalonia.Media.Color value) => SetVariant(key, value);
+
+          public void SetMatrix3x2Parameter(string key, Matrix3x2 value) => SetVariant(key, value);
+
+          public void SetMatrix4x4Parameter(string key, Matrix4x4 value) => SetVariant(key, value);
+
+          public void SetQuaternionParameter(string key, Quaternion value) => SetVariant(key, value);
+
+          public void SetReferenceParameter(string key, CompositionObject compositionObject) =>
+              _propertySet.Set(key, compositionObject);
+
+          public void SetScalarParameter(string key, float value) => SetVariant(key, value);
+
+          public void SetVector2Parameter(string key, Vector2 value) => SetVariant(key, value);
+
+          public void SetVector3Parameter(string key, Vector3 value) => SetVariant(key, value);
+
+          public void SetVector4Parameter(string key, Vector4 value) => SetVariant(key, value);
+          
+          // TODO: void SetExpressionReferenceParameter(string parameterName, IAnimationObject source)
+
+          public string? Target { get; set; }
+
+          internal abstract IAnimationInstance CreateInstance(ServerObject targetObject,
+              ExpressionVariant? finalValue);
+
+          internal PropertySetSnapshot CreateSnapshot(bool server) 
+              => _propertySet.Snapshot(server, 1);
+
+          void ICompositionAnimationBase.InternalOnly()
+          {
+              
+          }
+      }
+}

src/Avalonia.Base/Rendering/Composition/Animations/CompositionAnimationGroup.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using Avalonia.Rendering.Composition.Transport;
+
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    public class CompositionAnimationGroup : CompositionObject, ICompositionAnimationBase
+    {
+        internal List<CompositionAnimation> Animations { get; } = new List<CompositionAnimation>();
+        void ICompositionAnimationBase.InternalOnly()
+        {
+            
+        }
+
+        public void Add(CompositionAnimation value) => Animations.Add(value);
+        public void Remove(CompositionAnimation value) => Animations.Remove(value);
+        public void RemoveAll() => Animations.Clear();
+
+        public CompositionAnimationGroup(Compositor compositor) : base(compositor, null!)
+        {
+        }
+
+        private protected override IChangeSetPool ChangeSetPool => throw new InvalidOperationException();
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/ExpressionAnimation.cs

@@ -0,0 +1,34 @@
+// ReSharper disable CheckNamespace
+using System;
+using Avalonia.Rendering.Composition.Expressions;
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    public class ExpressionAnimation : CompositionAnimation
+    {
+        private string? _expression;
+        private Expression? _parsedExpression;
+        
+        internal ExpressionAnimation(Compositor compositor) : base(compositor)
+        {
+        }
+
+        public string? Expression
+        {
+            get => _expression;
+            set
+            {
+                _expression = value;
+                _parsedExpression = null;
+            }
+        }
+
+        private Expression ParsedExpression => _parsedExpression ??= ExpressionParser.Parse(_expression.AsSpan());
+
+        internal override IAnimationInstance CreateInstance(
+            ServerObject targetObject, ExpressionVariant? finalValue)
+            => new ExpressionAnimationInstance(ParsedExpression,
+                targetObject, finalValue, CreateSnapshot(true));
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/ExpressionAnimationInstance.cs

@@ -0,0 +1,44 @@
+using System;
+using Avalonia.Rendering.Composition.Expressions;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    internal class ExpressionAnimationInstance : IAnimationInstance
+    {
+        private readonly Expression _expression;
+        private readonly IExpressionObject _target;
+        private ExpressionVariant _startingValue;
+        private readonly ExpressionVariant? _finalValue;
+        private readonly PropertySetSnapshot _parameters;
+
+        public ExpressionVariant Evaluate(TimeSpan now, ExpressionVariant currentValue)
+        {
+            var ctx = new ExpressionEvaluationContext
+            {
+                Parameters = _parameters,
+                Target = _target,
+                ForeignFunctionInterface = BuiltInExpressionFfi.Instance,
+                StartingValue = _startingValue,
+                FinalValue = _finalValue ?? _startingValue,
+                CurrentValue = currentValue
+            };
+            return _expression.Evaluate(ref ctx);
+        }
+
+        public void Start(TimeSpan startedAt, ExpressionVariant startingValue)
+        {
+            _startingValue = startingValue;
+        }
+
+        public ExpressionAnimationInstance(Expression expression,
+            IExpressionObject target,
+            ExpressionVariant? finalValue,
+            PropertySetSnapshot parameters)
+        {
+            _expression = expression;
+            _target = target;
+            _finalValue = finalValue;
+            _parameters = parameters;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/IAnimationInstance.cs

@@ -0,0 +1,11 @@
+using System;
+using Avalonia.Rendering.Composition.Expressions;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    internal interface IAnimationInstance
+    {
+        ExpressionVariant Evaluate(TimeSpan now, ExpressionVariant currentValue);
+        void Start(TimeSpan startedAt, ExpressionVariant startingValue);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/ICompositionAnimationBase.cs

@@ -0,0 +1,12 @@
+// ReSharper disable CheckNamespace
+
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    public interface ICompositionAnimationBase
+    {
+        internal void InternalOnly();
+    }
+
+}

src/Avalonia.Base/Rendering/Composition/Animations/ImplicitAnimationCollection.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    public class ImplicitAnimationCollection : CompositionObject, IDictionary<string, ICompositionAnimationBase>
+    {
+        private Dictionary<string, ICompositionAnimationBase> _inner = new Dictionary<string, ICompositionAnimationBase>();
+        private IDictionary<string, ICompositionAnimationBase> _innerface;
+        internal ImplicitAnimationCollection(Compositor compositor) : base(compositor, null!)
+        {
+            _innerface = _inner;
+        }
+
+        private protected override IChangeSetPool ChangeSetPool => throw new InvalidOperationException();
+
+        public IEnumerator<KeyValuePair<string, ICompositionAnimationBase>> GetEnumerator() => _inner.GetEnumerator();
+
+        IEnumerator IEnumerable.GetEnumerator() => ((IEnumerable) _inner).GetEnumerator();
+
+        void ICollection<KeyValuePair<string, ICompositionAnimationBase>>.Add(KeyValuePair<string, ICompositionAnimationBase> item) => _innerface.Add(item);
+
+        public void Clear() => _inner.Clear();
+
+        bool ICollection<KeyValuePair<string, ICompositionAnimationBase>>.Contains(KeyValuePair<string, ICompositionAnimationBase> item) => _innerface.Contains(item);
+
+        void ICollection<KeyValuePair<string, ICompositionAnimationBase>>.CopyTo(KeyValuePair<string, ICompositionAnimationBase>[] array, int arrayIndex) => _innerface.CopyTo(array, arrayIndex);
+
+        bool ICollection<KeyValuePair<string, ICompositionAnimationBase>>.Remove(KeyValuePair<string, ICompositionAnimationBase> item) => _innerface.Remove(item);
+
+        public int Count => _inner.Count;
+
+        bool ICollection<KeyValuePair<string, ICompositionAnimationBase>>.IsReadOnly => _innerface.IsReadOnly;
+
+        public void Add(string key, ICompositionAnimationBase value) => _inner.Add(key, value);
+
+        public bool ContainsKey(string key) => _inner.ContainsKey(key);
+
+        public bool Remove(string key) => _inner.Remove(key);
+
+        public bool TryGetValue(string key, [MaybeNullWhen(false)] out ICompositionAnimationBase value) =>
+            _inner.TryGetValue(key, out value);
+
+        public ICompositionAnimationBase this[string key]
+        {
+            get => _inner[key];
+            set => _inner[key] = value;
+        }
+
+        ICollection<string> IDictionary<string, ICompositionAnimationBase>.Keys => _innerface.Keys;
+
+        ICollection<ICompositionAnimationBase> IDictionary<string, ICompositionAnimationBase>.Values =>
+            _innerface.Values;
+        
+        // UWP compat
+        public uint Size => (uint) Count;
+
+        public IReadOnlyDictionary<string, ICompositionAnimationBase> GetView() =>
+            new Dictionary<string, ICompositionAnimationBase>(this);
+
+        public bool HasKey(string key) => ContainsKey(key);
+        public void Insert(string key, ICompositionAnimationBase animation) => Add(key, animation);
+
+        public ICompositionAnimationBase? Lookup(string key)
+        {
+            _inner.TryGetValue(key, out var rv);
+            return rv;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/Interpolators.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Numerics;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    internal interface IInterpolator<T>
+    {
+        T Interpolate(T from, T to, float progress);
+    }
+
+    class ScalarInterpolator : IInterpolator<float>
+    {
+        public float Interpolate(float @from, float to, float progress) => @from + (to - @from) * progress;
+        
+        public static ScalarInterpolator Instance { get; } = new ScalarInterpolator();
+    }
+
+    class Vector2Interpolator : IInterpolator<Vector2>
+    {
+        public Vector2 Interpolate(Vector2 @from, Vector2 to, float progress) 
+            => Vector2.Lerp(@from, to, progress);
+        
+        public static Vector2Interpolator Instance { get; } = new Vector2Interpolator();
+    }
+    
+    class Vector3Interpolator : IInterpolator<Vector3>
+    {
+        public Vector3 Interpolate(Vector3 @from, Vector3 to, float progress) 
+            => Vector3.Lerp(@from, to, progress);
+        
+        public static Vector3Interpolator Instance { get; } = new Vector3Interpolator();
+    }
+    
+    class Vector4Interpolator : IInterpolator<Vector4>
+    {
+        public Vector4 Interpolate(Vector4 @from, Vector4 to, float progress) 
+            => Vector4.Lerp(@from, to, progress);
+        
+        public static Vector4Interpolator Instance { get; } = new Vector4Interpolator();
+    }
+    
+    class QuaternionInterpolator : IInterpolator<Quaternion>
+    {
+        public Quaternion Interpolate(Quaternion @from, Quaternion to, float progress) 
+            => Quaternion.Lerp(@from, to, progress);
+
+        public static QuaternionInterpolator Instance { get; } = new QuaternionInterpolator();
+    }
+    
+    class ColorInterpolator : IInterpolator<Avalonia.Media.Color>
+    {
+        static byte Lerp(float a, float b, float p) => (byte) Math.Max(0, Math.Min(255, (p * (b - a) + a)));
+
+        public static Avalonia.Media.Color
+            LerpRGB(Avalonia.Media.Color to, Avalonia.Media.Color from, float progress) =>
+            new Avalonia.Media.Color(Lerp(to.A, @from.A, progress),
+                Lerp(to.R, @from.R, progress),
+                Lerp(to.G, @from.G, progress),
+                Lerp(to.B, @from.B, progress));
+
+        public Avalonia.Media.Color Interpolate(Avalonia.Media.Color @from, Avalonia.Media.Color to, float progress)
+            => LerpRGB(@from, to, progress);
+        
+        public static ColorInterpolator Instance { get; } = new ColorInterpolator();
+    }
+
+    class BooleanInterpolator : IInterpolator<bool>
+    {
+        public bool Interpolate(bool @from, bool to, float progress) => progress >= 1 ? to : @from;
+        
+        public static BooleanInterpolator Instance { get; } = new BooleanInterpolator();
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/KeyFrameAnimation.cs

@@ -0,0 +1,53 @@
+namespace Avalonia.Rendering.Composition.Animations
+{
+    public abstract class KeyFrameAnimation : CompositionAnimation
+    {
+        internal KeyFrameAnimation(Compositor compositor) : base(compositor)
+        {
+        }
+        
+        public AnimationDelayBehavior DelayBehavior { get; set; }
+        public System.TimeSpan DelayTime { get; set; }
+        public AnimationDirection Direction { get; set; }
+        public System.TimeSpan Duration { get; set; }
+        public AnimationIterationBehavior IterationBehavior { get; set; }
+        public int IterationCount { get; set; } = 1;
+        public AnimationStopBehavior StopBehavior { get; set; }
+        
+        private protected abstract IKeyFrames KeyFrames { get; }
+        
+        public void InsertExpressionKeyFrame(float normalizedProgressKey, string value,
+            CompositionEasingFunction easingFunction) =>
+            KeyFrames.InsertExpressionKeyFrame(normalizedProgressKey, value, easingFunction);
+
+        public void InsertExpressionKeyFrame(float normalizedProgressKey, string value) 
+            => KeyFrames.InsertExpressionKeyFrame(normalizedProgressKey, value, new LinearEasingFunction(Compositor));
+    }
+
+    public enum AnimationDelayBehavior
+    {
+        SetInitialValueAfterDelay,
+        SetInitialValueBeforeDelay
+    }
+
+    public enum AnimationDirection
+    {
+        Normal,
+        Reverse,
+        Alternate,
+        AlternateReverse
+    }
+
+    public enum AnimationIterationBehavior
+    {
+        Count,
+        Forever
+    }
+
+    public enum AnimationStopBehavior
+    {
+        LeaveCurrentValue,
+        SetToInitialValue,
+        SetToFinalValue
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/KeyFrameAnimationInstance.cs

@@ -0,0 +1,139 @@
+using System;
+using Avalonia.Rendering.Composition.Expressions;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    class KeyFrameAnimationInstance<T> : IAnimationInstance where T : struct
+    {
+        private readonly IInterpolator<T> _interpolator;
+        private readonly ServerKeyFrame<T>[] _keyFrames;
+        private readonly PropertySetSnapshot _snapshot;
+        private readonly ExpressionVariant? _finalValue;
+        private readonly IExpressionObject _target;
+        private readonly AnimationDelayBehavior _delayBehavior;
+        private readonly TimeSpan _delayTime;
+        private readonly AnimationDirection _direction;
+        private readonly TimeSpan _duration;
+        private readonly AnimationIterationBehavior _iterationBehavior;
+        private readonly int _iterationCount;
+        private readonly AnimationStopBehavior _stopBehavior;
+        private TimeSpan _startedAt;
+        private T _startingValue;
+
+        public KeyFrameAnimationInstance(
+            IInterpolator<T> interpolator, ServerKeyFrame<T>[] keyFrames,
+            PropertySetSnapshot snapshot, ExpressionVariant? finalValue,
+            IExpressionObject target,
+            AnimationDelayBehavior delayBehavior, TimeSpan delayTime,
+            AnimationDirection direction, TimeSpan duration,
+            AnimationIterationBehavior iterationBehavior,
+            int iterationCount, AnimationStopBehavior stopBehavior)
+        {
+            _interpolator = interpolator;
+            _keyFrames = keyFrames;
+            _snapshot = snapshot;
+            _finalValue = finalValue;
+            _target = target;
+            _delayBehavior = delayBehavior;
+            _delayTime = delayTime;
+            _direction = direction;
+            _duration = duration;
+            _iterationBehavior = iterationBehavior;
+            _iterationCount = iterationCount;
+            _stopBehavior = stopBehavior;
+            if (_keyFrames.Length == 0)
+                throw new InvalidOperationException("Animation has no key frames");
+            if(_duration.Ticks <= 0)
+                throw new InvalidOperationException("Invalid animation duration");
+        }
+
+        public ExpressionVariant Evaluate(TimeSpan now, ExpressionVariant currentValue)
+        {
+            var elapsed = now - _startedAt;
+            var starting = ExpressionVariant.Create(_startingValue);
+            var ctx = new ExpressionEvaluationContext
+            {
+                Parameters = _snapshot,
+                Target = _target,
+                CurrentValue = currentValue,
+                FinalValue = _finalValue ??  starting,
+                StartingValue = starting,
+                ForeignFunctionInterface = BuiltInExpressionFfi.Instance
+            };
+            
+            if (elapsed < _delayTime)
+            {
+                if (_delayBehavior == AnimationDelayBehavior.SetInitialValueBeforeDelay)
+                    return ExpressionVariant.Create(GetKeyFrame(ref ctx, _keyFrames[0]));
+                return currentValue;
+            }
+
+            elapsed -= _delayTime;
+            var iterationNumber = elapsed.Ticks / _duration.Ticks;
+            if (_iterationBehavior == AnimationIterationBehavior.Count
+                && iterationNumber >= _iterationCount)
+                return ExpressionVariant.Create(GetKeyFrame(ref ctx, _keyFrames[_keyFrames.Length - 1]));
+            
+            
+            var evenIterationNumber = iterationNumber % 2 == 0;
+            elapsed = TimeSpan.FromTicks(elapsed.Ticks % _duration.Ticks);
+
+            var reverse =
+                _direction == AnimationDirection.Alternate
+                    ? !evenIterationNumber
+                    : _direction == AnimationDirection.AlternateReverse
+                        ? evenIterationNumber
+                        : _direction == AnimationDirection.Reverse;
+
+            var iterationProgress = elapsed.TotalSeconds / _duration.TotalSeconds;
+            if (reverse)
+                iterationProgress = 1 - iterationProgress;
+
+            var left = new ServerKeyFrame<T>
+            {
+                Value = _startingValue
+            };
+            var right = _keyFrames[_keyFrames.Length - 1];
+            for (var c = 0; c < _keyFrames.Length; c++)
+            {
+                var kf = _keyFrames[c];
+                if (kf.Key < iterationProgress)
+                {
+                    // this is the last frame
+                    if (c == _keyFrames.Length - 1)
+                        return ExpressionVariant.Create(GetKeyFrame(ref ctx, kf));
+
+                    left = kf;
+                    right = _keyFrames[c + 1];
+                    break;
+                }
+            }
+
+            var keyProgress = Math.Max(0, Math.Min(1, (iterationProgress - left.Key) / (right.Key - left.Key)));
+
+            var easedKeyProgress = right.EasingFunction.Ease((float) keyProgress);
+            if (float.IsNaN(easedKeyProgress) || float.IsInfinity(easedKeyProgress))
+                return currentValue;
+            
+            return ExpressionVariant.Create(_interpolator.Interpolate(
+                GetKeyFrame(ref ctx, left),
+                GetKeyFrame(ref ctx, right),
+                easedKeyProgress
+            ));
+        }
+
+        T GetKeyFrame(ref ExpressionEvaluationContext ctx, ServerKeyFrame<T> f)
+        {
+            if (f.Expression != null)
+                return f.Expression.Evaluate(ref ctx).CastOrDefault<T>();
+            else
+                return f.Value;
+        }
+
+        public void Start(TimeSpan startedAt, ExpressionVariant startingValue)
+        {
+            _startedAt = startedAt;
+            _startingValue = startingValue.CastOrDefault<T>();
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/KeyFrames.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using Avalonia.Rendering.Composition.Expressions;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    class KeyFrames<T> : List<KeyFrame<T>>, IKeyFrames
+    {
+        void Validate(float key)
+        {
+            if (key < 0 || key > 1)
+                throw new ArgumentException("Key frame key");
+            if (Count > 0 && this[Count - 1].NormalizedProgressKey > key)
+                throw new ArgumentException("Key frame key " + key + " is less than the previous one");
+        }
+        
+        public void InsertExpressionKeyFrame(float normalizedProgressKey, string value,
+            CompositionEasingFunction easingFunction)
+        {
+            Validate(normalizedProgressKey);
+            Add(new KeyFrame<T>
+            {
+                NormalizedProgressKey = normalizedProgressKey,
+                Expression = Expression.Parse(value),
+                EasingFunction = easingFunction
+            });
+        }
+
+        public void Insert(float normalizedProgressKey, T value, CompositionEasingFunction easingFunction)
+        {
+            Validate(normalizedProgressKey);
+            Add(new KeyFrame<T>
+            {
+                NormalizedProgressKey = normalizedProgressKey,
+                Value = value,
+                EasingFunction = easingFunction
+            });
+        }
+
+        public ServerKeyFrame<T>[] Snapshot()
+        {
+            var frames = new ServerKeyFrame<T>[Count];
+            for (var c = 0; c < Count; c++)
+            {
+                var f = this[c];
+                frames[c] = new ServerKeyFrame<T>
+                {
+                    Expression = f.Expression,
+                    Value = f.Value,
+                    EasingFunction = f.EasingFunction.Snapshot(),
+                    Key = f.NormalizedProgressKey
+                };
+            }
+            return frames;
+        }
+    }
+
+    struct KeyFrame<T>
+    {
+        public float NormalizedProgressKey;
+        public T Value;
+        public Expression Expression;
+        public CompositionEasingFunction EasingFunction;
+    }
+    
+    struct ServerKeyFrame<T>
+    {
+        public T Value;
+        public Expression Expression;
+        public IEasingFunction EasingFunction;
+        public float Key;
+    }
+
+    
+
+    interface IKeyFrames
+    {
+        public void InsertExpressionKeyFrame(float normalizedProgressKey, string value, CompositionEasingFunction easingFunction);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Animations/PropertySetSnapshot.cs

@@ -0,0 +1,46 @@
+using System.Collections.Generic;
+using Avalonia.Rendering.Composition.Expressions;
+
+namespace Avalonia.Rendering.Composition.Animations
+{
+    internal class PropertySetSnapshot : IExpressionParameterCollection, IExpressionObject
+    {
+        private readonly Dictionary<string, Value> _dic;
+
+        public struct Value
+        {
+            public ExpressionVariant Variant;
+            public IExpressionObject Object;
+
+            public Value(IExpressionObject o)
+            {
+                Object = o;
+                Variant = default;
+            }
+
+            public static implicit operator Value(ExpressionVariant v) => new Value
+            {
+                Variant = v
+            };
+        }
+
+        public PropertySetSnapshot(Dictionary<string, Value> dic)
+        {
+            _dic = dic;
+        }
+
+        public ExpressionVariant GetParameter(string name)
+        {
+            _dic.TryGetValue(name, out var v);
+            return v.Variant;
+        }
+
+        public IExpressionObject GetObjectParameter(string name)
+        {
+            _dic.TryGetValue(name, out var v);
+            return v.Object;
+        }
+
+        public ExpressionVariant GetProperty(string name) => GetParameter(name);
+    }
+}

src/Avalonia.Base/Rendering/Composition/CompositingRenderer.cs

@@ -0,0 +1,194 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+using System.Runtime.InteropServices;
+using Avalonia.Collections;
+using Avalonia.Media;
+using Avalonia.Rendering.Composition.Drawing;
+using Avalonia.Rendering.Composition.Server;
+using Avalonia.Threading;
+using Avalonia.VisualTree;
+
+namespace Avalonia.Rendering.Composition;
+
+public class CompositingRenderer : RendererBase, IRendererWithCompositor
+{
+    private readonly IRenderRoot _root;
+    private readonly Compositor _compositor;
+    private readonly IDeferredRendererLock? _rendererLock;
+    CompositionDrawingContext _recorder = new();
+    DrawingContext _recordingContext;
+    private HashSet<Visual> _dirty = new();
+    private HashSet<Visual> _recalculateChildren = new();
+    private readonly CompositionTarget _target;
+    private bool _queuedUpdate;
+    private Action _update;
+
+    public CompositingRenderer(IRenderRoot root,
+        Compositor compositor, 
+        IDeferredRendererLock? rendererLock = null)
+    {
+        _root = root;
+        _compositor = compositor;
+        _recordingContext = new DrawingContext(_recorder);
+        _rendererLock = rendererLock ?? new ManagedDeferredRendererLock();
+        _target = compositor.CreateCompositionTarget(root.CreateRenderTarget);
+        _target.Root = ((Visual)root!.VisualRoot!).AttachToCompositor(compositor);
+        _update = Update;
+    }
+    
+    public bool DrawFps { get; set; }
+    public bool DrawDirtyRects { get; set; }
+    public event EventHandler<SceneInvalidatedEventArgs>? SceneInvalidated;
+
+    void QueueUpdate()
+    {
+        if(_queuedUpdate)
+            return;
+        _queuedUpdate = true;
+        Dispatcher.UIThread.Post(_update, DispatcherPriority.Composition);
+    }
+    public void AddDirty(IVisual visual)
+    {
+        _dirty.Add((Visual)visual);
+        QueueUpdate();
+    }
+
+    public IEnumerable<IVisual> HitTest(Point p, IVisual root, Func<IVisual, bool> filter)
+    {
+        var res = _target.TryHitTest(new Vector2((float)p.X, (float)p.Y));
+        if(res == null)
+            yield break;
+        for (var index = res.Count - 1; index >= 0; index--)
+        {
+            var v = res[index];
+            if (v is CompositionDrawListVisual dv)
+            {
+                if (filter == null || filter(dv.Visual))
+                    yield return dv.Visual;
+            }
+        }
+    }
+
+    public IVisual? HitTestFirst(Point p, IVisual root, Func<IVisual, bool> filter)
+    {
+        // TODO: Optimize
+        return HitTest(p, root, filter).FirstOrDefault();
+    }
+
+    public void RecalculateChildren(IVisual visual)
+    {
+        _recalculateChildren.Add((Visual)visual);
+        QueueUpdate();
+    }
+
+    private void SyncChildren(Visual v)
+    {
+        //TODO: Optimize by moving that logic to Visual itself
+        if(v.CompositionVisual == null)
+            return;
+        var compositionChildren = v.CompositionVisual.Children;
+        var visualChildren = (AvaloniaList<IVisual>)v.GetVisualChildren();
+        if (compositionChildren.Count == visualChildren.Count)
+        {
+            bool mismatch = false;
+            for(var c=0; c<visualChildren.Count; c++)
+                if(!object.ReferenceEquals(compositionChildren[c], ((Visual)visualChildren[c]).CompositionVisual))
+                {
+                    mismatch = true;
+                    break;
+                }
+            
+            if(!mismatch)
+                return;
+        }
+        compositionChildren.Clear();
+        foreach (var ch in v.GetVisualChildren())
+        {
+            var compositionChild = ((Visual)ch).CompositionVisual;
+            if (compositionChild != null)
+                compositionChildren.Add(compositionChild);
+        }
+    }
+    
+    private void Update()
+    {
+        _queuedUpdate = false;
+        foreach (var visual in _dirty)
+        {
+            var comp = visual.CompositionVisual;
+            if(comp == null)
+                continue;
+            
+            // TODO: Optimize all of that by moving to the Visual itself, so we won't have to recalculate every time
+            comp.Offset = new Vector3((float)visual.Bounds.Left, (float)visual.Bounds.Top, 0);
+            comp.Size = new Vector2((float)visual.Bounds.Width, (float)visual.Bounds.Height);
+            comp.Visible = visual.IsVisible;
+            comp.Opacity = (float)visual.Opacity;
+            comp.ClipToBounds = visual.ClipToBounds;
+            comp.Clip = visual.Clip?.PlatformImpl;
+            
+            var renderTransform = Matrix.Identity;
+
+            if (visual.RenderTransform != null)
+            {
+                var origin = visual.RenderTransformOrigin.ToPixels(new Size(visual.Bounds.Width, visual.Bounds.Height));
+                var offset = Matrix.CreateTranslation(origin);
+                renderTransform = (-offset) * visual.RenderTransform.Value * (offset);
+            }
+
+            
+
+            if (visual.HasMirrorTransform)
+            {
+                var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, visual.Bounds.Width, 0);
+                renderTransform *= mirrorMatrix;
+            }
+
+            comp.TransformMatrix = renderTransform;
+
+            _recorder.BeginUpdate(comp.DrawList ?? new CompositionDrawList());
+            visual.Render(_recordingContext);
+            comp.DrawList = _recorder.EndUpdate();
+
+            SyncChildren(visual);
+        }
+        foreach(var v in _recalculateChildren)
+            if (!_dirty.Contains(v))
+                SyncChildren(v);
+        _dirty.Clear();
+        _recalculateChildren.Clear();
+    }
+    
+    public void Resized(Size size)
+    {
+    }
+
+    public void Paint(Rect rect)
+    {
+        // We render only on the render thread for now
+        Update();
+        
+        Compositor.RequestCommitAsync().Wait();
+    }
+
+    public void Start() => _target.IsEnabled = true;
+
+    public void Stop()
+    {
+        _target.IsEnabled = true;
+    }
+    
+    public void Dispose()
+    {
+        Stop();
+        _target.Dispose();
+        // Wait for the composition batch to be applied and rendered to guarantee that
+        // render target is not used anymore and can be safely disposed
+        _compositor.RequestCommitAsync().Wait();
+    }
+
+
+    public Compositor Compositor => _compositor;
+}

src/Avalonia.Base/Rendering/Composition/CompositionDrawListVisual.cs

@@ -0,0 +1,44 @@
+using System.Numerics;
+using Avalonia.Rendering.Composition.Drawing;
+using Avalonia.Rendering.Composition.Server;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition;
+
+internal class CompositionDrawListVisual : CompositionContainerVisual
+{
+    public Visual Visual { get; }
+
+    private new DrawListVisualChanges Changes => (DrawListVisualChanges)base.Changes;
+    private CompositionDrawList? _drawList;
+    public CompositionDrawList? DrawList
+    {
+        get => _drawList;
+        set
+        {
+            _drawList?.Dispose();
+            _drawList = value;
+            Changes.DrawCommands = value?.Clone();
+        }
+    }
+
+    private protected override IChangeSetPool ChangeSetPool => DrawListVisualChanges.Pool;
+
+    internal CompositionDrawListVisual(Compositor compositor, ServerCompositionContainerVisual server, Visual visual) : base(compositor, server)
+    {
+        Visual = visual;
+    }
+
+    internal override bool HitTest(Vector2 point)
+    {
+        if (DrawList == null)
+            return false;
+        var pt = new Point(point.X, point.Y);
+        if (Visual is ICustomHitTest custom)
+            return custom.HitTest(pt);
+        foreach (var op in DrawList)
+            if (op.Item.HitTest(pt))
+                return true;
+        return false;
+    }
+}

src/Avalonia.Base/Rendering/Composition/CompositionEasingFunction.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Numerics;
+using Avalonia.Rendering.Composition.Transport;
+using Avalonia.Rendering.Composition.Utils;
+
+namespace Avalonia.Rendering.Composition
+{
+    public abstract class CompositionEasingFunction : CompositionObject
+    {
+        internal CompositionEasingFunction(Compositor compositor) : base(compositor, null!)
+        {
+        }
+
+        private protected override IChangeSetPool ChangeSetPool => throw new InvalidOperationException();
+
+        internal abstract IEasingFunction Snapshot();
+    }
+    
+    internal interface IEasingFunction
+    {
+        float Ease(float progress);
+    }
+
+    public sealed class DelegateCompositionEasingFunction : CompositionEasingFunction
+    {
+        private readonly Easing _func;
+
+        public delegate float EasingDelegate(float progress);
+
+        internal DelegateCompositionEasingFunction(Compositor compositor, EasingDelegate func) : base(compositor)
+        {
+            _func = new Easing(func);
+        }
+
+        class Easing : IEasingFunction
+        {
+            private readonly EasingDelegate _func;
+
+            public Easing(EasingDelegate func)
+            {
+                _func = func;
+            }
+            
+            public float Ease(float progress) => _func(progress);
+        }
+
+        internal override IEasingFunction Snapshot() => _func;
+    }
+
+    public class LinearEasingFunction : CompositionEasingFunction
+    {
+        public LinearEasingFunction(Compositor compositor) : base(compositor)
+        {
+        }
+
+        class Linear : IEasingFunction
+        {
+            public float Ease(float progress) => progress;
+        }
+
+        private static readonly Linear Instance = new Linear();
+        internal override IEasingFunction Snapshot() => Instance;
+    }
+
+    public class CubicBezierEasingFunction : CompositionEasingFunction
+    {
+        private CubicBezier _bezier;
+        public Vector2 ControlPoint1 { get; }
+        public Vector2 ControlPoint2 { get; }
+        //cubic-bezier(0.25, 0.1, 0.25, 1.0)
+        internal CubicBezierEasingFunction(Compositor compositor, Vector2 controlPoint1, Vector2 controlPoint2) : base(compositor)
+        {
+            ControlPoint1 = controlPoint1;
+            ControlPoint2 = controlPoint2;
+            if (controlPoint1.X < 0 || controlPoint1.X > 1 || controlPoint2.X < 0 || controlPoint2.X > 1)
+                throw new ArgumentException();
+            _bezier = new CubicBezier(controlPoint1.X, controlPoint1.Y, controlPoint2.X, controlPoint2.Y);
+        }
+
+        class EasingFunction : IEasingFunction
+        {
+            private readonly CubicBezier _bezier;
+
+            public EasingFunction(CubicBezier bezier)
+            {
+                _bezier = bezier;
+            }
+            
+            public float Ease(float progress) => (float)_bezier.Solve(progress);
+        }
+
+        internal static IEasingFunction Ease { get; } = new EasingFunction(new CubicBezier(0.25, 0.1, 0.25, 1));
+
+        internal override IEasingFunction Snapshot() => new EasingFunction(_bezier);
+    }
+
+}

src/Avalonia.Base/Rendering/Composition/CompositionGradientBrush.cs

@@ -0,0 +1,16 @@
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition
+{
+    public partial class CompositionGradientBrush : CompositionBrush
+    {
+        internal CompositionGradientBrush(Compositor compositor, ServerCompositionGradientBrush server) : base(compositor, server)
+        {
+            ColorStops = new CompositionGradientStopCollection(compositor, server.Stops);
+        }
+        
+        public CompositionGradientStopCollection ColorStops { get; }
+    }
+    
+    
+}

src/Avalonia.Base/Rendering/Composition/CompositionObject.cs

@@ -0,0 +1,125 @@
+using System;
+using Avalonia.Rendering.Composition.Animations;
+using Avalonia.Rendering.Composition.Expressions;
+using Avalonia.Rendering.Composition.Server;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition
+{
+    public abstract class CompositionObject : IDisposable, IExpressionObject
+    {
+        public ImplicitAnimationCollection? ImplicitAnimations { get; set; }
+        internal CompositionObject(Compositor compositor, ServerObject server)
+        {
+            Compositor = compositor;
+            Server = server;
+        }
+        
+        public Compositor Compositor { get; }
+        internal ServerObject Server { get; }
+        public bool IsDisposed { get; private set; }
+        private ChangeSet? _changes;
+
+        private static void ThrowInvalidOperation() =>
+            throw new InvalidOperationException("There is no server-side counterpart for this object");
+        
+        private protected ChangeSet Changes
+        {
+            get
+            {
+                // ReSharper disable once ConditionIsAlwaysTrueOrFalse
+                if (Server == null) ThrowInvalidOperation();
+                var currentBatch = Compositor.CurrentBatch;
+                if (_changes != null && _changes.Batch != currentBatch)
+                    _changes = null;
+                if (_changes == null)
+                {
+                    _changes = ChangeSetPool.Get(Server!, currentBatch);
+                    currentBatch.Changes!.Add(_changes);
+                    Compositor.QueueImplicitBatchCommit();
+                }
+
+                return _changes;
+            }
+        }
+
+        private protected abstract IChangeSetPool ChangeSetPool { get; }
+
+        public void Dispose()
+        {
+            Changes.Dispose = true;
+            IsDisposed = true;
+        }
+
+        internal virtual ExpressionVariant GetPropertyForAnimation(string name)
+        {
+            return default;
+        }
+
+        ExpressionVariant IExpressionObject.GetProperty(string name) => GetPropertyForAnimation(name);
+
+        public void StartAnimation(string propertyName, CompositionAnimation animation)
+            => StartAnimation(propertyName, animation, null);
+        
+        internal virtual void StartAnimation(string propertyName, CompositionAnimation animation, ExpressionVariant? finalValue = null)
+        {
+            throw new ArgumentException("Unknown property " + propertyName);
+        }
+
+        public void StartAnimationGroup(ICompositionAnimationBase grp)
+        {
+            if (grp is CompositionAnimation animation)
+            {
+                if(animation.Target == null)
+                    throw new ArgumentException("Animation Target can't be null");
+                StartAnimation(animation.Target, animation);
+            }
+            else if (grp is CompositionAnimationGroup group)
+            {
+                foreach (var a in group.Animations)
+                {
+                    if (a.Target == null)
+                        throw new ArgumentException("Animation Target can't be null");
+                    StartAnimation(a.Target, a);
+                }
+            }
+        }
+
+        bool StartAnimationGroupPart(CompositionAnimation animation, string target, ExpressionVariant finalValue)
+        {
+            if(animation.Target == null)
+                throw new ArgumentException("Animation Target can't be null");
+            if (animation.Target == target)
+            {
+                StartAnimation(animation.Target, animation, finalValue);
+                return true;
+            }
+            else
+            {
+                StartAnimation(animation.Target, animation);
+                return false;
+            }
+        }
+        
+        internal bool StartAnimationGroup(ICompositionAnimationBase grp, string target, ExpressionVariant finalValue)
+        {
+            if (grp is CompositionAnimation animation)
+                return StartAnimationGroupPart(animation, target, finalValue);
+            if (grp is CompositionAnimationGroup group)
+            {
+                var matched = false;
+                foreach (var a in group.Animations)
+                {
+                    if (a.Target == null)
+                        throw new ArgumentException("Animation Target can't be null");
+                    if (StartAnimationGroupPart(a, target, finalValue))
+                        matched = true;
+                }
+
+                return matched;
+            }
+
+            throw new ArgumentException();
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/CompositionPropertySet.cs

@@ -0,0 +1,132 @@
+using System;
+using System.Collections.Generic;
+using System.Numerics;
+using Avalonia.Rendering.Composition.Animations;
+using Avalonia.Rendering.Composition.Expressions;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition
+{
+    public class CompositionPropertySet : CompositionObject
+    {
+        private readonly Dictionary<string, ExpressionVariant> _variants = new Dictionary<string, ExpressionVariant>();
+        private readonly Dictionary<string, CompositionObject> _objects = new Dictionary<string, CompositionObject>();
+        
+        internal CompositionPropertySet(Compositor compositor) : base(compositor, null!)
+        {
+        }
+
+        private protected override IChangeSetPool ChangeSetPool => throw new NotSupportedException();
+
+        internal void Set(string key, ExpressionVariant value)
+        {
+            _objects.Remove(key);
+            _variants[key] = value;
+        }
+
+        internal void Set(string key, CompositionObject obj)
+        {
+            _objects[key] = obj ?? throw new ArgumentNullException(nameof(obj));
+            _variants.Remove(key);
+        }
+        public void InsertColor(string propertyName, Avalonia.Media.Color value) => Set(propertyName, value);
+
+        public void InsertMatrix3x2(string propertyName, Matrix3x2 value) => Set(propertyName, value);
+
+        public void InsertMatrix4x4(string propertyName, Matrix4x4 value) => Set(propertyName, value);
+
+        public void InsertQuaternion(string propertyName, Quaternion value) => Set(propertyName, value);
+
+        public void InsertScalar(string propertyName, float value) => Set(propertyName, value);
+        public void InsertVector2(string propertyName, Vector2 value) => Set(propertyName, value);
+
+        public void InsertVector3(string propertyName, Vector3 value) => Set(propertyName, value);
+
+        public void InsertVector4(string propertyName, Vector4 value) => Set(propertyName, value);
+
+
+        CompositionGetValueStatus TryGetVariant<T>(string key, out T value) where T : struct
+        {
+            value = default;
+            if (!_variants.TryGetValue(key, out var v))
+                return _objects.ContainsKey(key)
+                    ? CompositionGetValueStatus.TypeMismatch
+                    : CompositionGetValueStatus.NotFound;
+
+            return v.TryCast(out value) ? CompositionGetValueStatus.Succeeded : CompositionGetValueStatus.TypeMismatch;
+        }
+
+        public CompositionGetValueStatus TryGetColor(string propertyName, out Avalonia.Media.Color value) 
+            => TryGetVariant(propertyName, out value);
+
+        public CompositionGetValueStatus TryGetMatrix3x2(string propertyName, out Matrix3x2 value)
+            => TryGetVariant(propertyName, out value);
+
+        public CompositionGetValueStatus TryGetMatrix4x4(string propertyName, out Matrix4x4 value)
+            => TryGetVariant(propertyName, out value);
+
+        public CompositionGetValueStatus TryGetQuaternion(string propertyName, out Quaternion value)
+            => TryGetVariant(propertyName, out value);
+
+        
+        public CompositionGetValueStatus TryGetScalar(string propertyName, out float value)
+            => TryGetVariant(propertyName, out value);
+
+        public CompositionGetValueStatus TryGetVector2(string propertyName, out Vector2 value)
+            => TryGetVariant(propertyName, out value);
+
+        public CompositionGetValueStatus TryGetVector3(string propertyName, out Vector3 value)
+            => TryGetVariant(propertyName, out value);
+
+        public CompositionGetValueStatus TryGetVector4(string propertyName, out Vector4 value)
+            => TryGetVariant(propertyName, out value);
+
+
+        public void InsertBoolean(string propertyName, bool value) => Set(propertyName, value);
+
+        public CompositionGetValueStatus TryGetBoolean(string propertyName, out bool value)
+            => TryGetVariant(propertyName, out value);
+
+        internal void ClearAll()
+        {
+            _objects.Clear();
+            _variants.Clear();
+        }
+
+        internal void Clear(string key)
+        {
+            _objects.Remove(key);
+            _variants.Remove(key);
+        }
+
+        internal PropertySetSnapshot Snapshot(bool server, int allowedNestingLevel)
+        {
+            var dic = new Dictionary<string, PropertySetSnapshot.Value>(_objects.Count + _variants.Count);
+            foreach (var o in _objects)
+            {
+                if (o.Value is CompositionPropertySet ps)
+                {
+                    if (allowedNestingLevel <= 0)
+                        throw new InvalidOperationException("PropertySet depth limit reached");
+                    dic[o.Key] = new PropertySetSnapshot.Value(ps.Snapshot(server, allowedNestingLevel - 1));
+                }
+                else if (o.Value.Server == null)
+                    throw new InvalidOperationException($"Object of type {o.Value.GetType()} is not allowed");
+                else
+                    dic[o.Key] = new PropertySetSnapshot.Value(server ? (IExpressionObject) o.Value.Server : o.Value);
+            }
+
+            foreach (var v in _variants)
+                dic[v.Key] = v.Value;
+            
+            return new PropertySetSnapshot(dic);
+        }
+    }
+
+    public enum CompositionGetValueStatus
+    {
+        Succeeded,
+        TypeMismatch,
+        NotFound
+    }
+}

src/Avalonia.Base/Rendering/Composition/CompositionTarget.cs

@@ -0,0 +1,107 @@
+using System.Collections.Generic;
+using System.Numerics;
+using Avalonia.Collections.Pooled;
+
+namespace Avalonia.Rendering.Composition
+{
+    public partial class CompositionTarget
+    {
+        partial void OnRootChanged()
+        {
+            if (Root != null)
+                Root.Root = this;
+        }
+
+        partial void OnRootChanging()
+        {
+            if (Root != null)
+                Root.Root = null;
+        }
+        
+        public PooledList<CompositionVisual>? TryHitTest(Vector2 point)
+        {
+            Server.Readback.NextRead();
+            if (Root == null)
+                return null;
+            var res = new PooledList<CompositionVisual>();
+            HitTestCore(Root, point, res);
+            return res;
+        }
+
+        public Vector2? TryTransformToVisual(CompositionVisual visual, Vector2 point)
+        {
+            if (visual.Root != this)
+                return null;
+            var v = visual;
+            var m = Matrix3x2.Identity;
+            while (v != null)
+            {
+                if (!TryGetInvertedTransform(v, out var cm))
+                    return null;
+                m = m * cm;
+                v = v.Parent;
+            }
+
+            return Vector2.Transform(point, m);
+        }
+
+        bool TryGetInvertedTransform(CompositionVisual visual, out Matrix3x2 matrix)
+        {
+            var m = visual.TryGetServerTransform();
+            if (m == null)
+            {
+                matrix = default;
+                return false;
+            }
+
+            // TODO: Use Matrix3x3
+            var m32 = new Matrix3x2(m.Value.M11, m.Value.M12, m.Value.M21, m.Value.M22, m.Value.M41, m.Value.M42);
+            
+            return Matrix3x2.Invert(m32, out matrix);
+        }
+
+        bool TryTransformTo(CompositionVisual visual, ref Vector2 v)
+        {
+            if (TryGetInvertedTransform(visual, out var m))
+            {
+                v = Vector2.Transform(v, m);
+                return true;
+            }
+
+            return false;
+        }
+        
+        bool HitTestCore(CompositionVisual visual, Vector2 point, PooledList<CompositionVisual> result)
+        {
+            //TODO: Check readback too
+            if (visual.Visible == false)
+                return false;
+            if (!TryTransformTo(visual, ref point))
+                return false;
+            if (point.X >= 0 && point.Y >= 0 && point.X <= visual.Size.X && point.Y <= visual.Size.Y)
+            {
+                bool success = false;
+                // Hit-test the current node
+                if (visual.HitTest(point))
+                {
+                    result.Add(visual);
+                    success = true;
+                }
+                
+                // Inspect children too
+                if(visual is CompositionContainerVisual cv)
+                    for (var c = cv.Children.Count - 1; c >= 0; c--)
+                    {
+                        var ch = cv.Children[c];
+                        var hit = HitTestCore(ch, point, result);
+                        if (hit)
+                            return true;
+                    }
+
+                return success;
+            }
+
+            return false;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Compositor.cs

@@ -0,0 +1,143 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Numerics;
+using System.Threading.Tasks;
+using Avalonia.Platform;
+using Avalonia.Rendering.Composition.Animations;
+using Avalonia.Rendering.Composition.Server;
+using Avalonia.Rendering.Composition.Transport;
+using Avalonia.Threading;
+
+
+namespace Avalonia.Rendering.Composition
+{
+    public partial class Compositor
+    {
+        private ServerCompositor _server;
+        private Batch _currentBatch;
+        private bool _implicitBatchCommitQueued;
+        private Action _implicitBatchCommit;
+
+        internal Batch CurrentBatch => _currentBatch;
+        internal ServerCompositor Server => _server;
+        internal CompositionEasingFunction DefaultEasing { get; }
+
+        private Compositor(ServerCompositor server)
+        {
+            _server = server;
+            _currentBatch = new Batch();
+            _implicitBatchCommit = ImplicitBatchCommit;
+            DefaultEasing = new CubicBezierEasingFunction(this,
+                new Vector2(0.25f, 0.1f), new Vector2(0.25f, 1f));
+        }
+
+        public CompositionTarget CreateCompositionTarget(Func<IRenderTarget> renderTargetFactory)
+        {
+            return new CompositionTarget(this, new ServerCompositionTarget(_server, renderTargetFactory));
+        }
+
+        public Task RequestCommitAsync()
+        {
+            var batch = CurrentBatch;
+            _currentBatch = new Batch();
+            batch.CommitedAt = Server.Clock.Elapsed;
+            _server.EnqueueBatch(batch);
+            return batch.Completed;
+        }
+
+        public static Compositor Create(IRenderLoop timer)
+        {
+            return new Compositor(new ServerCompositor(timer));
+        }
+
+        public void Dispose()
+        {
+            
+        }
+
+        public CompositionContainerVisual CreateContainerVisual() => new(this, new ServerCompositionContainerVisual(_server));
+        
+        public CompositionSolidColorVisual CreateSolidColorVisual() => new CompositionSolidColorVisual(this, 
+            new ServerCompositionSolidColorVisual(_server));
+
+        public CompositionSolidColorVisual CreateSolidColorVisual(Avalonia.Media.Color color)
+        {
+            var v = new CompositionSolidColorVisual(this, new ServerCompositionSolidColorVisual(_server));
+            v.Color = color;
+            return v;
+        }
+
+        public CompositionSpriteVisual CreateSpriteVisual() => new CompositionSpriteVisual(this, new ServerCompositionSpriteVisual(_server));
+
+        public CompositionLinearGradientBrush CreateLinearGradientBrush() 
+            => new CompositionLinearGradientBrush(this, new ServerCompositionLinearGradientBrush(_server));
+
+        public CompositionColorGradientStop CreateColorGradientStop()
+            => new CompositionColorGradientStop(this, new ServerCompositionColorGradientStop(_server));
+
+        public CompositionColorGradientStop CreateColorGradientStop(float offset, Avalonia.Media.Color color)
+        {
+            var stop = CreateColorGradientStop();
+            stop.Offset = offset;
+            stop.Color = color;
+            return stop;
+        }
+
+        // We want to make it 100% async later
+        /*
+        public CompositionBitmapSurface LoadBitmapSurface(Stream stream)
+        {
+            var bmp = _server.Backend.LoadCpuMemoryBitmap(stream);
+            return new CompositionBitmapSurface(this, bmp);
+        }
+
+        public async Task<CompositionBitmapSurface> LoadBitmapSurfaceAsync(Stream stream)
+        {
+            var bmp = await Task.Run(() => _server.Backend.LoadCpuMemoryBitmap(stream));
+            return new CompositionBitmapSurface(this, bmp);
+        }
+        */
+        public CompositionColorBrush CreateColorBrush(Avalonia.Media.Color color) =>
+            new CompositionColorBrush(this, new ServerCompositionColorBrush(_server)) {Color = color};
+
+        public CompositionSurfaceBrush CreateSurfaceBrush() =>
+            new CompositionSurfaceBrush(this, new ServerCompositionSurfaceBrush(_server));
+
+        /*
+        public CompositionGaussianBlurEffectBrush CreateGaussianBlurEffectBrush() =>
+            new CompositionGaussianBlurEffectBrush(this, new ServerCompositionGaussianBlurEffectBrush(_server));
+
+        public CompositionBackdropBrush CreateBackdropBrush() =>
+            new CompositionBackdropBrush(this, new ServerCompositionBackdropBrush(Server));*/
+
+        public ExpressionAnimation CreateExpressionAnimation() => new ExpressionAnimation(this);
+
+        public ExpressionAnimation CreateExpressionAnimation(string expression) => new ExpressionAnimation(this)
+        {
+            Expression = expression
+        };
+
+        public ImplicitAnimationCollection CreateImplicitAnimationCollection() => new ImplicitAnimationCollection(this);
+
+        public CompositionAnimationGroup CreateAnimationGroup() => new CompositionAnimationGroup(this);
+
+        internal CustomDrawVisual<T> CreateCustomDrawVisual<T>(ICustomDrawVisualRenderer<T> renderer,
+            ICustomDrawVisualHitTest<T>? hitTest = null) where T : IEquatable<T> =>
+            new CustomDrawVisual<T>(this, renderer, hitTest);
+
+        public void QueueImplicitBatchCommit()
+        {
+            if(_implicitBatchCommitQueued)
+                return;
+            _implicitBatchCommitQueued = true;
+            Dispatcher.UIThread.Post(_implicitBatchCommit, DispatcherPriority.CompositionBatch);
+        }
+
+        private void ImplicitBatchCommit()
+        {
+            _implicitBatchCommitQueued = false;
+            RequestCommitAsync();
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/CompositorRenderLoopTask.cs

@@ -0,0 +1,20 @@
+using System;
+
+namespace Avalonia.Rendering.Composition;
+
+partial class Compositor
+{
+    class CompositorRenderLoopTask : IRenderLoopTask
+    {
+        public bool NeedsUpdate { get; }
+        public void Update(TimeSpan time)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void Render()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/ContainerVisual.cs

@@ -0,0 +1,20 @@
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition
+{
+    public class CompositionContainerVisual : CompositionVisual
+    {
+        public CompositionVisualCollection Children { get; }
+        internal CompositionContainerVisual(Compositor compositor, ServerCompositionContainerVisual server) : base(compositor, server)
+        {
+            Children = new CompositionVisualCollection(this, server.Children);
+        }
+
+        private protected override void OnRootChanged()
+        {
+            foreach (var ch in Children)
+                ch.Root = Root;
+            base.OnRootChanged();
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/CustomDrawVisual.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Numerics;
+using Avalonia.Platform;
+using Avalonia.Rendering.Composition.Server;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition
+{
+    internal class CustomDrawVisual<TData> : CompositionContainerVisual where TData : IEquatable<TData>
+    {
+        private readonly ICustomDrawVisualHitTest<TData>? _hitTest;
+
+        internal CustomDrawVisual(Compositor compositor, ICustomDrawVisualRenderer<TData> renderer,
+            ICustomDrawVisualHitTest<TData>? hitTest) : base(compositor, 
+            new ServerCustomDrawVisual<TData>(compositor.Server, renderer))
+        {
+            _hitTest = hitTest;
+        }
+
+        private TData? _data;
+
+        static bool Eq(TData? left, TData? right)
+        {
+            if (left == null && right == null)
+                return true;
+            if (left == null)
+                return false;
+            return left.Equals(right);
+        }
+        
+        public TData? Data
+        {
+            get => _data;
+            set
+            {
+                if (!Eq(_data, value))
+                {
+                    ((CustomDrawVisualChanges<TData?>) Changes).Data.Value = value;
+                    _data = value;
+                }
+            }
+        }
+        
+        private protected override IChangeSetPool ChangeSetPool => CustomDrawVisualChanges<TData>.Pool;
+    }
+
+    public interface ICustomDrawVisualRenderer<TData>
+    {
+        void Render(IDrawingContextImpl canvas, TData? data);
+    }
+
+    public interface ICustomDrawVisualHitTest<TData>
+    {
+        bool HitTest(TData data, Vector2 vector2);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Drawing/CompositionDrawList.cs

@@ -0,0 +1,81 @@
+using System;
+using Avalonia.Collections.Pooled;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.Utilities;
+
+namespace Avalonia.Rendering.Composition.Drawing;
+
+internal class CompositionDrawList : PooledList<IRef<IDrawOperation>>
+{
+    public CompositionDrawList()
+    {
+        
+    }
+
+    public CompositionDrawList(int capacity) : base(capacity)
+    {
+        
+    }
+    
+    public override void Dispose()
+    {
+        foreach(var item in this)
+            item.Dispose();
+        base.Dispose();
+    }
+
+    public CompositionDrawList Clone()
+    {
+        var clone = new CompositionDrawList(Count);
+        foreach (var r in this)
+            clone.Add(r.Clone());
+        return clone;
+    }
+}
+
+internal class CompositionDrawListBuilder
+{
+    private CompositionDrawList? _operations;
+    private bool _owns;
+
+    public void Reset(CompositionDrawList? previousOperations)
+    {
+        _operations = previousOperations;
+        _owns = false;
+    }
+
+    public CompositionDrawList DrawOperations => _operations ?? new CompositionDrawList();
+
+    void MakeWritable(int atIndex)
+    {
+        if(_owns)
+            return;
+        _owns = true;
+        var newOps = new CompositionDrawList(_operations?.Count ?? Math.Max(1, atIndex));
+        if (_operations != null)
+        {
+            for (var c = 0; c < atIndex; c++)
+                newOps.Add(_operations[c].Clone());
+        }
+
+        _operations = newOps;
+    }
+
+    public void ReplaceDrawOperation(int index, IDrawOperation node)
+    {
+        MakeWritable(index);
+        DrawOperations.Add(RefCountable.Create(node));
+    }
+
+    public void AddDrawOperation(IDrawOperation node)
+    {
+        MakeWritable(DrawOperations.Count);
+        DrawOperations.Add(RefCountable.Create(node));
+    }
+
+    public void TrimTo(int count)
+    {
+        if (count < DrawOperations.Count)
+            DrawOperations.RemoveRange(count, DrawOperations.Count - count);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Drawing/CompositionDrawingContext.cs

@@ -0,0 +1,383 @@
+using System;
+using System.Collections.Generic;
+using System.Numerics;
+using Avalonia.Media;
+using Avalonia.Media.Imaging;
+using Avalonia.Platform;
+using Avalonia.Rendering.Composition.Drawing;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.Utilities;
+using Avalonia.VisualTree;
+namespace Avalonia.Rendering.Composition;
+
+internal class CompositionDrawingContext : IDrawingContextImpl
+{
+    private CompositionDrawListBuilder _builder = new();
+    private int _drawOperationIndex;
+
+    /// <inheritdoc/>
+    public Matrix Transform { get; set; } = Matrix.Identity;
+
+    /// <inheritdoc/>
+    public void Clear(Color color)
+    {
+        // Cannot clear a deferred scene.
+    }
+
+    /// <inheritdoc/>
+    public void Dispose()
+    {
+        // Nothing to do here since we allocate no unmanaged resources.
+    }
+
+    public void BeginUpdate(CompositionDrawList list)
+    {
+        _builder.Reset(list);
+        _drawOperationIndex = 0;
+    }
+
+    public CompositionDrawList EndUpdate()
+    {
+        _builder.TrimTo(_drawOperationIndex);
+        return _builder.DrawOperations!;
+    }
+
+    /// <inheritdoc/>
+    public void DrawGeometry(IBrush? brush, IPen? pen, IGeometryImpl geometry)
+    {
+        var next = NextDrawAs<GeometryNode>();
+
+        if (next == null || !next.Item.Equals(Transform, brush, pen, geometry))
+        {
+            Add(new GeometryNode(Transform, brush, pen, geometry, CreateChildScene(brush)));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void DrawBitmap(IRef<IBitmapImpl> source, double opacity, Rect sourceRect, Rect destRect,
+        BitmapInterpolationMode bitmapInterpolationMode)
+    {
+        var next = NextDrawAs<ImageNode>();
+
+        if (next == null ||
+            !next.Item.Equals(Transform, source, opacity, sourceRect, destRect, bitmapInterpolationMode))
+        {
+            Add(new ImageNode(Transform, source, opacity, sourceRect, destRect, bitmapInterpolationMode));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void DrawBitmap(IRef<IBitmapImpl> source, IBrush opacityMask, Rect opacityMaskRect, Rect sourceRect)
+    {
+        // This method is currently only used to composite layers so shouldn't be called here.
+        throw new NotSupportedException();
+    }
+
+    /// <inheritdoc/>
+    public void DrawLine(IPen pen, Point p1, Point p2)
+    {
+        var next = NextDrawAs<LineNode>();
+
+        if (next == null || !next.Item.Equals(Transform, pen, p1, p2))
+        {
+            Add(new LineNode(Transform, pen, p1, p2, CreateChildScene(pen.Brush)));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void DrawRectangle(IBrush? brush, IPen? pen, RoundedRect rect,
+        BoxShadows boxShadows = default)
+    {
+        var next = NextDrawAs<RectangleNode>();
+
+        if (next == null || !next.Item.Equals(Transform, brush, pen, rect, boxShadows))
+        {
+            Add(new RectangleNode(Transform, brush, pen, rect, boxShadows, CreateChildScene(brush)));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void DrawRectangle(IExperimentalAcrylicMaterial material, RoundedRect rect)
+    {
+        var next = NextDrawAs<ExperimentalAcrylicNode>();
+
+        if (next == null || !next.Item.Equals(Transform, material, rect))
+        {
+            Add(new ExperimentalAcrylicNode(Transform, material, rect));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    public void DrawEllipse(IBrush? brush, IPen? pen, Rect rect)
+    {
+        var next = NextDrawAs<EllipseNode>();
+
+        if (next == null || !next.Item.Equals(Transform, brush, pen, rect))
+        {
+            Add(new EllipseNode(Transform, brush, pen, rect, CreateChildScene(brush)));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    public void Custom(ICustomDrawOperation custom)
+    {
+        var next = NextDrawAs<CustomDrawOperation>();
+        if (next == null || !next.Item.Equals(Transform, custom))
+            Add(new CustomDrawOperation(custom, Transform));
+        else
+            ++_drawOperationIndex;
+    }
+
+    /// <inheritdoc/>
+    public void DrawGlyphRun(IBrush foreground, GlyphRun glyphRun)
+    {
+        var next = NextDrawAs<GlyphRunNode>();
+
+        if (next == null || !next.Item.Equals(Transform, foreground, glyphRun))
+        {
+            Add(new GlyphRunNode(Transform, foreground, glyphRun, CreateChildScene(foreground)));
+        }
+
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    public IDrawingContextLayerImpl CreateLayer(Size size)
+    {
+        throw new NotSupportedException("Creating layers on a deferred drawing context not supported");
+    }
+
+    /// <inheritdoc/>
+    public void PopClip()
+    {
+        var next = NextDrawAs<ClipNode>();
+
+        if (next == null || !next.Item.Equals(null))
+        {
+            Add(new ClipNode());
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PopGeometryClip()
+    {
+        var next = NextDrawAs<GeometryClipNode>();
+
+        if (next == null || !next.Item.Equals(null))
+        {
+            Add(new GeometryClipNode());
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PopBitmapBlendMode()
+    {
+        var next = NextDrawAs<BitmapBlendModeNode>();
+
+        if (next == null || !next.Item.Equals(null))
+        {
+            Add(new BitmapBlendModeNode());
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PopOpacity()
+    {
+        var next = NextDrawAs<OpacityNode>();
+
+        if (next == null || !next.Item.Equals(null))
+        {
+            Add(new OpacityNode());
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PopOpacityMask()
+    {
+        var next = NextDrawAs<OpacityMaskNode>();
+
+        if (next == null || !next.Item.Equals(null, null))
+        {
+            Add(new OpacityMaskNode());
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PushClip(Rect clip)
+    {
+        var next = NextDrawAs<ClipNode>();
+
+        if (next == null || !next.Item.Equals(Transform, clip))
+        {
+            Add(new ClipNode(Transform, clip));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc />
+    public void PushClip(RoundedRect clip)
+    {
+        var next = NextDrawAs<ClipNode>();
+
+        if (next == null || !next.Item.Equals(Transform, clip))
+        {
+            Add(new ClipNode(Transform, clip));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PushGeometryClip(IGeometryImpl? clip)
+    {
+        if (clip is null)
+            return;
+
+        var next = NextDrawAs<GeometryClipNode>();
+
+        if (next == null || !next.Item.Equals(Transform, clip))
+        {
+            Add(new GeometryClipNode(Transform, clip));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PushOpacity(double opacity)
+    {
+        var next = NextDrawAs<OpacityNode>();
+
+        if (next == null || !next.Item.Equals(opacity))
+        {
+            Add(new OpacityNode(opacity));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PushOpacityMask(IBrush mask, Rect bounds)
+    {
+        var next = NextDrawAs<OpacityMaskNode>();
+
+        if (next == null || !next.Item.Equals(mask, bounds))
+        {
+            Add(new OpacityMaskNode(mask, bounds, CreateChildScene(mask)));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    /// <inheritdoc/>
+    public void PushBitmapBlendMode(BitmapBlendingMode blendingMode)
+    {
+        var next = NextDrawAs<BitmapBlendModeNode>();
+
+        if (next == null || !next.Item.Equals(blendingMode))
+        {
+            Add(new BitmapBlendModeNode(blendingMode));
+        }
+        else
+        {
+            ++_drawOperationIndex;
+        }
+    }
+
+    private void Add<T>(T node) where T : class, IDrawOperation
+    {
+        if (_drawOperationIndex < _builder!.DrawOperations.Count)
+        {
+            _builder.ReplaceDrawOperation(_drawOperationIndex, node);
+        }
+        else
+        {
+            _builder.AddDrawOperation(node);
+        }
+
+        ++_drawOperationIndex;
+    }
+
+    private IRef<T>? NextDrawAs<T>() where T : class, IDrawOperation
+    {
+        return _drawOperationIndex < _builder!.DrawOperations.Count
+            ? _builder.DrawOperations[_drawOperationIndex] as IRef<T>
+            : null;
+    }
+
+    private IDictionary<IVisual, Scene>? CreateChildScene(IBrush? brush)
+    {
+        /*
+        var visualBrush = brush as VisualBrush;
+
+        if (visualBrush != null)
+        {
+            var visual = visualBrush.Visual;
+
+            if (visual != null)
+            {
+                (visual as IVisualBrushInitialize)?.EnsureInitialized();
+                var scene = new Scene(visual);
+                _sceneBuilder.UpdateAll(scene);
+                return new Dictionary<IVisual, Scene> { { visualBrush.Visual, scene } };
+            }
+        }*/
+
+        return null;
+    }
+}

src/Avalonia.Base/Rendering/Composition/Enums.cs

@@ -0,0 +1,120 @@
+using System;
+
+namespace Avalonia.Rendering.Composition
+{
+    public enum CompositionBlendMode
+    {
+        /// <summary>No regions are enabled. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_clr.svg)</summary>
+        Clear,
+
+        /// <summary>Only the source will be present. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_src.svg)</summary>
+        Src,
+
+        /// <summary>Only the destination will be present. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_dst.svg)</summary>
+        Dst,
+
+        /// <summary>Source is placed over the destination. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_src-over.svg)</summary>
+        SrcOver,
+
+        /// <summary>Destination is placed over the source. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_dst-over.svg)</summary>
+        DstOver,
+
+        /// <summary>The source that overlaps the destination, replaces the destination. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_src-in.svg)</summary>
+        SrcIn,
+
+        /// <summary>Destination which overlaps the source, replaces the source. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_dst-in.svg)</summary>
+        DstIn,
+
+        /// <summary>Source is placed, where it falls outside of the destination. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_src-out.svg)</summary>
+        SrcOut,
+
+        /// <summary>Destination is placed, where it falls outside of the source. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_dst-out.svg)</summary>
+        DstOut,
+
+        /// <summary>Source which overlaps the destination, replaces the destination. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_src-atop.svg)</summary>
+        SrcATop,
+
+        /// <summary>Destination which overlaps the source replaces the source. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_dst-atop.svg)</summary>
+        DstATop,
+
+        /// <summary>The non-overlapping regions of source and destination are combined. [Porter Duff Compositing Operators] (https://drafts.fxtf.org/compositing-1/examples/PD_xor.svg)</summary>
+        Xor,
+
+        /// <summary>Display the sum of the source image and destination image. [Porter Duff Compositing Operators]</summary>
+        Plus,
+
+        /// <summary>Multiplies all components (= alpha and color). [Separable Blend Modes]</summary>
+        Modulate,
+
+        /// <summary>Multiplies the complements of the backdrop and source CompositionColorvalues, then complements the result. [Separable Blend Modes]</summary>
+        Screen,
+
+        /// <summary>Multiplies or screens the colors, depending on the backdrop CompositionColorvalue. [Separable Blend Modes]</summary>
+        Overlay,
+
+        /// <summary>Selects the darker of the backdrop and source colors. [Separable Blend Modes]</summary>
+        Darken,
+
+        /// <summary>Selects the lighter of the backdrop and source colors. [Separable Blend Modes]</summary>
+        Lighten,
+
+        /// <summary>Brightens the backdrop CompositionColorto reflect the source color. [Separable Blend Modes]</summary>
+        ColorDodge,
+
+        /// <summary>Darkens the backdrop CompositionColorto reflect the source color. [Separable Blend Modes]</summary>
+        ColorBurn,
+
+        /// <summary>Multiplies or screens the colors, depending on the source CompositionColorvalue. [Separable Blend Modes]</summary>
+        HardLight,
+
+        /// <summary>Darkens or lightens the colors, depending on the source CompositionColorvalue. [Separable Blend Modes]</summary>
+        SoftLight,
+
+        /// <summary>Subtracts the darker of the two constituent colors from the lighter color. [Separable Blend Modes]</summary>
+        Difference,
+
+        /// <summary>Produces an effect similar to that of the Difference mode but lower in contrast. [Separable Blend Modes]</summary>
+        Exclusion,
+
+        /// <summary>The source CompositionColoris multiplied by the destination CompositionColorand replaces the destination [Separable Blend Modes]</summary>
+        Multiply,
+
+        /// <summary>Creates a CompositionColorwith the hue of the source CompositionColorand the saturation and luminosity of the backdrop color. [Non-Separable Blend Modes]</summary>
+        Hue,
+
+        /// <summary>Creates a CompositionColorwith the saturation of the source CompositionColorand the hue and luminosity of the backdrop color. [Non-Separable Blend Modes]</summary>
+        Saturation,
+
+        /// <summary>Creates a CompositionColorwith the hue and saturation of the source CompositionColorand the luminosity of the backdrop color. [Non-Separable Blend Modes]</summary>
+        Color,
+
+        /// <summary>Creates a CompositionColorwith the luminosity of the source CompositionColorand the hue and saturation of the backdrop color. [Non-Separable Blend Modes]</summary>
+        Luminosity,
+    }
+
+    public enum CompositionGradientExtendMode
+    {
+        Clamp,
+        Wrap,
+        Mirror
+    }
+    
+    [Flags]
+    public enum CompositionTileMode
+    {
+        None = 0,
+        TileX = 1,
+        TileY = 2,
+        FlipX = 4,
+        FlipY = 8,
+        Tile = TileX | TileY,
+        Flip = FlipX | FlipY
+    }
+
+    public enum CompositionStretch
+    {
+        None = 0,
+        Fill = 1,
+        //TODO: Uniform, UniformToFill
+    }
+}

src/Avalonia.Base/Rendering/Composition/Expressions/BuiltInExpressionFfi.cs

@@ -0,0 +1,234 @@
+using System;
+using System.Collections.Generic;
+using System.Numerics;
+using Avalonia.Rendering.Composition.Animations;
+using Avalonia.Rendering.Composition.Utils;
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal class BuiltInExpressionFfi : IExpressionForeignFunctionInterface
+    {
+        private readonly DelegateExpressionFfi _registry;
+
+        static float Lerp(float a, float b, float p) => p * (b - a) + a;
+
+        static Matrix3x2 Inverse(Matrix3x2 m)
+        {
+            Matrix3x2.Invert(m, out var r);
+            return r;
+        }
+
+        static Matrix4x4 Inverse(Matrix4x4 m)
+        {
+            Matrix4x4.Invert(m, out var r);
+            return r;
+        }
+
+        static float SmoothStep(float edge0, float edge1, float x)
+        {
+            var t = MathExt.Clamp((x - edge0) / (edge1 - edge0), 0.0f, 1.0f);
+            return t * t * (3.0f - 2.0f * t);
+        }
+
+        static Vector2 SmoothStep(Vector2 edge0, Vector2 edge1, Vector2 x)
+        {
+            return new Vector2(
+                SmoothStep(edge0.X, edge1.X, x.X),
+                SmoothStep(edge0.Y, edge1.Y, x.Y)
+                
+                );
+        }
+        static Vector3 SmoothStep(Vector3 edge0, Vector3 edge1, Vector3 x)
+        {
+            return new Vector3(
+                SmoothStep(edge0.X, edge1.X, x.X),
+                SmoothStep(edge0.Y, edge1.Y, x.Y),
+                SmoothStep(edge0.Z, edge1.Z, x.Z)
+                
+                );
+        }
+
+        static Vector4 SmoothStep(Vector4 edge0, Vector4 edge1, Vector4 x)
+        {
+            return new Vector4(
+                SmoothStep(edge0.X, edge1.X, x.X),
+                SmoothStep(edge0.Y, edge1.Y, x.Y),
+                SmoothStep(edge0.Z, edge1.Z, x.Z),
+                SmoothStep(edge0.W, edge1.W, x.W)
+            );
+        }
+
+        private BuiltInExpressionFfi()
+        {
+            _registry = new DelegateExpressionFfi
+            {
+                {"Abs", (float f) => Math.Abs(f)},
+                {"Abs", (Vector2 v) => Vector2.Abs(v)},
+                {"Abs", (Vector3 v) => Vector3.Abs(v)},
+                {"Abs", (Vector4 v) => Vector4.Abs(v)},
+
+                {"ACos", (float f) => (float) Math.Acos(f)},
+                {"ASin", (float f) => (float) Math.Asin(f)},
+                {"ATan", (float f) => (float) Math.Atan(f)},
+                {"Ceil", (float f) => (float) Math.Ceiling(f)},
+
+                {"Clamp", (float a1, float a2, float a3) => MathExt.Clamp(a1, a2, a3)},
+                {"Clamp", (Vector2 a1, Vector2 a2, Vector2 a3) => Vector2.Clamp(a1, a2, a3)},
+                {"Clamp", (Vector3 a1, Vector3 a2, Vector3 a3) => Vector3.Clamp(a1, a2, a3)},
+                {"Clamp", (Vector4 a1, Vector4 a2, Vector4 a3) => Vector4.Clamp(a1, a2, a3)},
+
+                {"Concatenate", (Quaternion a1, Quaternion a2) => Quaternion.Concatenate(a1, a2)},
+                {"Cos", (float a) => (float) Math.Cos(a)},
+
+                /*
+                TODO:
+                    ColorHsl(Float h, Float s, Float l)
+                    ColorLerpHSL(Color colorTo, CompositionColorcolorFrom, Float progress)
+                */
+
+                {
+                    "ColorLerp", (Avalonia.Media.Color to, Avalonia.Media.Color from, float progress) =>
+                        ColorInterpolator.LerpRGB(to, from, progress)
+                },
+                {
+                    "ColorLerpRGB", (Avalonia.Media.Color to, Avalonia.Media.Color from, float progress) =>
+                        ColorInterpolator.LerpRGB(to, from, progress)
+                },
+                {
+                    "ColorRGB", (float a, float r, float g, float b) => Avalonia.Media.Color.FromArgb(
+                        (byte) MathExt.Clamp(a, 0, 255),
+                        (byte) MathExt.Clamp(r, 0, 255),
+                        (byte) MathExt.Clamp(g, 0, 255),
+                        (byte) MathExt.Clamp(b, 0, 255)
+                    )
+                },
+
+                {"Distance", (Vector2 a1, Vector2 a2) => Vector2.Distance(a1, a2)},
+                {"Distance", (Vector3 a1, Vector3 a2) => Vector3.Distance(a1, a2)},
+                {"Distance", (Vector4 a1, Vector4 a2) => Vector4.Distance(a1, a2)},
+
+                {"DistanceSquared", (Vector2 a1, Vector2 a2) => Vector2.DistanceSquared(a1, a2)},
+                {"DistanceSquared", (Vector3 a1, Vector3 a2) => Vector3.DistanceSquared(a1, a2)},
+                {"DistanceSquared", (Vector4 a1, Vector4 a2) => Vector4.DistanceSquared(a1, a2)},
+
+                {"Floor", (float v) => (float) Math.Floor(v)},
+
+                {"Inverse", (Matrix3x2 v) => Inverse(v)},
+                {"Inverse", (Matrix4x4 v) => Inverse(v)},
+
+
+                {"Length", (Vector2 a1) => a1.Length()},
+                {"Length", (Vector3 a1) => a1.Length()},
+                {"Length", (Vector4 a1) => a1.Length()},
+                {"Length", (Quaternion a1) => a1.Length()},
+
+                {"LengthSquared", (Vector2 a1) => a1.LengthSquared()},
+                {"LengthSquared", (Vector3 a1) => a1.LengthSquared()},
+                {"LengthSquared", (Vector4 a1) => a1.LengthSquared()},
+                {"LengthSquared", (Quaternion a1) => a1.LengthSquared()},
+
+                {"Lerp", (float a1, float a2, float a3) => Lerp(a1, a2, a3)},
+                {"Lerp", (Vector2 a1, Vector2 a2, float a3) => Vector2.Lerp(a1, a2, a3)},
+                {"Lerp", (Vector3 a1, Vector3 a2, float a3) => Vector3.Lerp(a1, a2, a3)},
+                {"Lerp", (Vector4 a1, Vector4 a2, float a3) => Vector4.Lerp(a1, a2, a3)},
+
+
+                {"Ln", (float f) => (float) Math.Log(f)},
+                {"Log10", (float f) => (float) Math.Log10(f)},
+
+                {"Matrix3x2.CreateFromScale", (Vector2 v) => Matrix3x2.CreateScale(v)},
+                {"Matrix3x2.CreateFromTranslation", (Vector2 v) => Matrix3x2.CreateTranslation(v)},
+                {"Matrix3x2.CreateRotation", (float v) => Matrix3x2.CreateRotation(v)},
+                {"Matrix3x2.CreateScale", (Vector2 v) => Matrix3x2.CreateScale(v)},
+                {"Matrix3x2.CreateSkew", (float a1, float a2, Vector2 a3) => Matrix3x2.CreateSkew(a1, a2, a3)},
+                {"Matrix3x2.CreateTranslation", (Vector2 v) => Matrix3x2.CreateScale(v)},
+                {
+                    "Matrix3x2", (float m11, float m12, float m21, float m22, float m31, float m32) =>
+                        new Matrix3x2(m11, m12, m21, m22, m31, m32)
+                },
+                {"Matrix4x4.CreateFromAxisAngle", (Vector3 v, float angle) => Matrix4x4.CreateFromAxisAngle(v, angle)},
+                {"Matrix4x4.CreateFromScale", (Vector3 v) => Matrix4x4.CreateScale(v)},
+                {"Matrix4x4.CreateFromTranslation", (Vector3 v) => Matrix4x4.CreateTranslation(v)},
+                {"Matrix4x4.CreateScale", (Vector3 v) => Matrix4x4.CreateScale(v)},
+                {"Matrix4x4.CreateTranslation", (Vector3 v) => Matrix4x4.CreateScale(v)},
+                {"Matrix4x4", (Matrix3x2 m) => new Matrix4x4(m)},
+                {
+                    "Matrix4x4",
+                    (float m11, float m12, float m13, float m14,
+                            float m21, float m22, float m23, float m24,
+                            float m31, float m32, float m33, float m34,
+                            float m41, float m42, float m43, float m44) =>
+                        new Matrix4x4(
+                            m11, m12, m13, m14,
+                            m21, m22, m23, m24,
+                            m31, m32, m33, m34,
+                            m41, m42, m43, m44)
+                },
+
+
+                {"Max", (float a1, float a2) => Math.Max(a1, a2)},
+                {"Max", (Vector2 a1, Vector2 a2) => Vector2.Max(a1, a2)},
+                {"Max", (Vector3 a1, Vector3 a2) => Vector3.Max(a1, a2)},
+                {"Max", (Vector4 a1, Vector4 a2) => Vector4.Max(a1, a2)},
+
+
+                {"Min", (float a1, float a2) => Math.Min(a1, a2)},
+                {"Min", (Vector2 a1, Vector2 a2) => Vector2.Min(a1, a2)},
+                {"Min", (Vector3 a1, Vector3 a2) => Vector3.Min(a1, a2)},
+                {"Min", (Vector4 a1, Vector4 a2) => Vector4.Min(a1, a2)},
+
+                {"Mod", (float a, float b) => a % b},
+
+                {"Normalize", (Quaternion a) => Quaternion.Normalize(a)},
+                {"Normalize", (Vector2 a) => Vector2.Normalize(a)},
+                {"Normalize", (Vector3 a) => Vector3.Normalize(a)},
+                {"Normalize", (Vector4 a) => Vector4.Normalize(a)},
+
+                {"Pow", (float a, float b) => (float) Math.Pow(a, b)},
+                {"Quaternion.CreateFromAxisAngle", (Vector3 a, float b) => Quaternion.CreateFromAxisAngle(a, b)},
+                {"Quaternion", (float a, float b, float c, float d) => new Quaternion(a, b, c, d)},
+
+                {"Round", (float a) => (float) Math.Round(a)},
+
+                {"Scale", (Matrix3x2 a, float b) => a * b},
+                {"Scale", (Matrix4x4 a, float b) => a * b},
+                {"Scale", (Vector2 a, float b) => a * b},
+                {"Scale", (Vector3 a, float b) => a * b},
+                {"Scale", (Vector4 a, float b) => a * b},
+
+                {"Sin", (float a) => (float) Math.Sin(a)},
+
+                {"SmoothStep", (float a1, float a2, float a3) => SmoothStep(a1, a2, a3)},
+                {"SmoothStep", (Vector2 a1, Vector2 a2, Vector2 a3) => SmoothStep(a1, a2, a3)},
+                {"SmoothStep", (Vector3 a1, Vector3 a2, Vector3 a3) => SmoothStep(a1, a2, a3)},
+                {"SmoothStep", (Vector4 a1, Vector4 a2, Vector4 a3) => SmoothStep(a1, a2, a3)},
+
+                // I have no idea how to do a spherical interpolation for a scalar value, so we are doing a linear one
+                {"Slerp", (float a1, float a2, float a3) => Lerp(a1, a2, a3)},
+                {"Slerp", (Quaternion a1, Quaternion a2, float a3) => Quaternion.Slerp(a1, a2, a3)},
+
+                {"Sqrt", (float a) => (float) Math.Sqrt(a)},
+                {"Square", (float a) => a * a},
+                {"Tan", (float a) => (float) Math.Tan(a)},
+
+                {"ToRadians", (float a) => (float) (a * Math.PI / 180)},
+                {"ToDegrees", (float a) => (float) (a * 180d / Math.PI)},
+
+                {"Transform", (Vector2 a, Matrix3x2 b) => Vector2.Transform(a, b)},
+                {"Transform", (Vector3 a, Matrix4x4 b) => Vector3.Transform(a, b)},
+
+                {"Vector2", (float a, float b) => new Vector2(a, b)},
+                {"Vector3", (float a, float b, float c) => new Vector3(a, b, c)},
+                {"Vector3", (Vector2 v2, float z) => new Vector3(v2, z)},
+                {"Vector4", (float a, float b, float c, float d) => new Vector4(a, b, c, d)},
+                {"Vector4", (Vector2 v2, float z, float w) => new Vector4(v2, z, w)},
+                {"Vector4", (Vector3 v3, float w) => new Vector4(v3, w)},
+            };
+        }
+
+        public bool Call(string name, IReadOnlyList<ExpressionVariant> arguments, out ExpressionVariant result) =>
+            _registry.Call(name, arguments, out result);
+
+        public static BuiltInExpressionFfi Instance { get; } = new BuiltInExpressionFfi();
+    }
+}

src/Avalonia.Base/Rendering/Composition/Expressions/DelegateExpressionFfi.cs

@@ -0,0 +1,181 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+using Avalonia.Media;
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal class DelegateExpressionFfi : IExpressionForeignFunctionInterface, IEnumerable
+    {
+        struct FfiRecord
+        {
+            public VariantType[] Types;
+            public Func<IReadOnlyList<ExpressionVariant>, ExpressionVariant> Delegate;
+        }
+
+        private readonly Dictionary<string, Dictionary<int, List<FfiRecord>>>
+            _registry = new Dictionary<string, Dictionary<int, List<FfiRecord>>>();
+
+        public bool Call(string name, IReadOnlyList<ExpressionVariant> arguments, out ExpressionVariant result)
+        {
+            result = default;
+            if (!_registry.TryGetValue(name, out var nameGroup))
+                return false;
+            if (!nameGroup.TryGetValue(arguments.Count, out var countGroup))
+                return false;
+            foreach (var record in countGroup)
+            {
+                var match = true;
+                for (var c = 0; c < arguments.Count; c++)
+                {
+                    if (record.Types[c] != arguments[c].Type)
+                    {
+                        match = false;
+                        break;
+                    }
+                }
+
+                if (match)
+                {
+                    result = record.Delegate(arguments);
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        // Stub for collection initializer 
+        IEnumerator IEnumerable.GetEnumerator() => Array.Empty<object>().GetEnumerator();
+
+        void Add(string name, Func<IReadOnlyList<ExpressionVariant>, ExpressionVariant> cb,
+            params Type[] types)
+        {
+            if (!_registry.TryGetValue(name, out var nameGroup))
+                _registry[name] = nameGroup =
+                    new Dictionary<int, List<FfiRecord>>();
+            if (!nameGroup.TryGetValue(types.Length, out var countGroup))
+                nameGroup[types.Length] = countGroup = new List<FfiRecord>();
+
+            countGroup.Add(new FfiRecord
+            {
+                Types = types.Select(t => TypeMap[t]).ToArray(),
+                Delegate = cb
+            });
+        }
+
+        static readonly Dictionary<Type, VariantType> TypeMap = new Dictionary<Type, VariantType>
+        {
+            [typeof(bool)] = VariantType.Boolean,
+            [typeof(float)] = VariantType.Scalar,
+            [typeof(Vector2)] = VariantType.Vector2,
+            [typeof(Vector3)] = VariantType.Vector3,
+            [typeof(Vector4)] = VariantType.Vector4,
+            [typeof(Matrix3x2)] = VariantType.Matrix3x2,
+            [typeof(Matrix4x4)] = VariantType.Matrix4x4,
+            [typeof(Quaternion)] = VariantType.Quaternion,
+            [typeof(Color)] = VariantType.Color
+        };
+
+        public void Add<T1>(string name, Func<T1, ExpressionVariant> cb) where T1 : struct
+        {
+            Add(name, args => cb(args[0].CastOrDefault<T1>()), typeof(T1));
+        }
+
+        public void Add<T1, T2>(string name, Func<T1, T2, ExpressionVariant> cb) where T1 : struct where T2 : struct
+        {
+            Add(name, args => cb(args[0].CastOrDefault<T1>(), args[1].CastOrDefault<T2>()), typeof(T1), typeof(T2));
+        }
+
+
+        public void Add<T1, T2, T3>(string name, Func<T1, T2, T3, ExpressionVariant> cb)
+            where T1 : struct where T2 : struct where T3 : struct
+        {
+            Add(name, args => cb(args[0].CastOrDefault<T1>(), args[1].CastOrDefault<T2>(), args[2].CastOrDefault<T3>()), typeof(T1), typeof(T2),
+                typeof(T3));
+        }
+        
+        public void Add<T1, T2, T3, T4>(string name, Func<T1, T2, T3, T4, ExpressionVariant> cb)
+            where T1 : struct where T2 : struct where T3 : struct where T4 : struct
+        {
+            Add(name, args => cb(
+                    args[0].CastOrDefault<T1>(),
+                    args[1].CastOrDefault<T2>(), 
+                    args[2].CastOrDefault<T3>(),
+                    args[3].CastOrDefault<T4>()),
+                typeof(T1), typeof(T2), typeof(T3), typeof(T4));
+        }
+        
+        public void Add<T1, T2, T3, T4, T5>(string name, Func<T1, T2, T3, T4, T5, ExpressionVariant> cb)
+            where T1 : struct where T2 : struct where T3 : struct where T4 : struct where T5 : struct
+        {
+            Add(name, args => cb(
+                    args[0].CastOrDefault<T1>(),
+                    args[1].CastOrDefault<T2>(), 
+                    args[2].CastOrDefault<T3>(),
+                    args[3].CastOrDefault<T4>(),
+                    args[4].CastOrDefault<T5>()),
+                typeof(T1), typeof(T2), typeof(T3), typeof(T4), typeof(T5));
+        }
+        
+        public void Add<T1, T2, T3, T4, T5, T6>(string name, Func<T1, T2, T3, T4, T5, T6, ExpressionVariant> cb)
+            where T1 : struct where T2 : struct where T3 : struct where T4 : struct where T5 : struct where T6 : struct
+        {
+            Add(name, args => cb(
+                    args[0].CastOrDefault<T1>(),
+                    args[1].CastOrDefault<T2>(), 
+                    args[2].CastOrDefault<T3>(),
+                    args[3].CastOrDefault<T4>(),
+                    args[4].CastOrDefault<T5>(),
+                    args[4].CastOrDefault<T6>()),
+                typeof(T1), typeof(T2), typeof(T3), typeof(T4), typeof(T5), typeof(T6));
+        }
+
+
+        public void Add<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>(string name,
+            Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, ExpressionVariant> cb)
+            where T1 : struct
+            where T2 : struct
+            where T3 : struct
+            where T4 : struct
+            where T5 : struct
+            where T6 : struct
+            where T7 : struct
+            where T8 : struct
+            where T9 : struct
+            where T10 : struct
+            where T11 : struct
+            where T12 : struct
+            where T13 : struct
+            where T14 : struct
+            where T15 : struct
+            where T16 : struct
+        {
+            Add(name, args => cb(
+                    args[0].CastOrDefault<T1>(),
+                    args[1].CastOrDefault<T2>(),
+                    args[2].CastOrDefault<T3>(),
+                    args[3].CastOrDefault<T4>(),
+                    args[4].CastOrDefault<T5>(),
+                    args[4].CastOrDefault<T6>(),
+                    args[4].CastOrDefault<T7>(),
+                    args[4].CastOrDefault<T8>(),
+                    args[4].CastOrDefault<T9>(),
+                    args[4].CastOrDefault<T10>(),
+                    args[4].CastOrDefault<T11>(),
+                    args[4].CastOrDefault<T12>(),
+                    args[4].CastOrDefault<T13>(),
+                    args[4].CastOrDefault<T14>(),
+                    args[4].CastOrDefault<T15>(),
+                    args[4].CastOrDefault<T16>()
+                ),
+                typeof(T1), typeof(T2), typeof(T3), typeof(T4),
+                typeof(T5), typeof(T6), typeof(T7), typeof(T8),
+                typeof(T9), typeof(T10), typeof(T11), typeof(T12),
+                typeof(T13), typeof(T14), typeof(T15), typeof(T16)
+            );
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Expressions/Expression.cs

@@ -0,0 +1,331 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Reflection;
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal abstract class Expression
+    {
+        public abstract ExpressionType Type { get; }
+        public static Expression Parse(string expression)
+        {
+            return ExpressionParser.Parse(expression.AsSpan());
+        }
+
+        public abstract ExpressionVariant Evaluate(ref ExpressionEvaluationContext context);
+
+        protected abstract string Print();
+        public override string ToString() => Print();
+
+        internal static string OperatorName(ExpressionType t)
+        {
+            var attr = typeof(ExpressionType).GetMember(t.ToString())[0]
+                .GetCustomAttribute<PrettyPrintStringAttribute>();
+            if (attr != null)
+                return attr.Name;
+            return t.ToString();
+        }
+    }
+
+    internal class PrettyPrintStringAttribute : Attribute
+    {
+        public string Name { get; }
+
+        public PrettyPrintStringAttribute(string name)
+        {
+            Name = name;
+        }
+    }
+    
+    internal enum ExpressionType
+    {
+        // Binary operators
+        [PrettyPrintString("+")]
+        Add,
+        [PrettyPrintString("-")]
+        Subtract,
+        [PrettyPrintString("/")]
+        Divide,
+        [PrettyPrintString("*")]
+        Multiply,
+        [PrettyPrintString(">")]
+        MoreThan,
+        [PrettyPrintString("<")]
+        LessThan,
+        [PrettyPrintString(">=")]
+        MoreThanOrEqual,
+        [PrettyPrintString("<=")]
+        LessThanOrEqual,
+        [PrettyPrintString("&&")]
+        LogicalAnd,
+        [PrettyPrintString("||")]
+        LogicalOr,
+        [PrettyPrintString("%")]
+        Remainder,
+        [PrettyPrintString("==")]
+        Equals,
+        [PrettyPrintString("!=")]
+        NotEquals,
+        // Unary operators
+        [PrettyPrintString("!")]
+        Not,
+        [PrettyPrintString("-")]
+        UnaryMinus,
+        // The rest
+        MemberAccess,
+        Parameter,
+        FunctionCall,
+        Keyword,
+        Constant,
+        ConditionalExpression
+    }
+
+    internal enum ExpressionKeyword
+    {
+        StartingValue,
+        CurrentValue,
+        FinalValue,
+        Target,
+        Pi,
+        True,
+        False
+    }
+
+    internal class ConditionalExpression : Expression
+    {
+        public Expression Condition { get; }
+        public Expression TruePart { get; }
+        public Expression FalsePart { get; }
+        public override ExpressionType Type => ExpressionType.ConditionalExpression;
+
+        public ConditionalExpression(Expression condition, Expression truePart, Expression falsePart)
+        {
+            Condition = condition;
+            TruePart = truePart;
+            FalsePart = falsePart;
+        }
+        
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context)
+        {
+            var cond = Condition.Evaluate(ref context);
+            if (cond.Type == VariantType.Boolean && cond.Boolean)
+                return TruePart.Evaluate(ref context);
+            return FalsePart.Evaluate(ref context);
+        }
+
+        protected override string Print() => $"({Condition}) ? ({TruePart}) : ({FalsePart})";
+    }
+    
+    internal class ConstantExpression : Expression
+    {
+        public float Constant { get; }
+        public override ExpressionType Type => ExpressionType.Constant;
+
+        public ConstantExpression(float constant)
+        {
+            Constant = constant;
+        }
+
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context) => Constant;
+        protected override string Print() => Constant.ToString(CultureInfo.InvariantCulture);
+    }
+
+    internal class FunctionCallExpression : Expression
+    {
+        public string Name { get; }
+        public List<Expression> Parameters { get; }
+        public override ExpressionType Type => ExpressionType.FunctionCall;
+
+        public FunctionCallExpression(string name, List<Expression> parameters)
+        {
+            Name = name;
+            Parameters = parameters;
+        }
+        
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context)
+        {
+            if (context.ForeignFunctionInterface == null)
+                return default;
+            var args = new List<ExpressionVariant>();
+            foreach (var expr in Parameters)
+                args.Add(expr.Evaluate(ref context));
+            if (!context.ForeignFunctionInterface.Call(Name, args, out var res))
+                return default;
+            return res;
+        }
+
+        protected override string Print()
+        {
+            return Name + "( (" + string.Join("), (", Parameters) + ") )";
+        }
+    }
+    
+    internal class MemberAccessExpression : Expression
+    {
+        public override ExpressionType Type => ExpressionType.MemberAccess;
+        public Expression Target { get; }
+        public string Member { get; }
+
+        public MemberAccessExpression(Expression target, string member)
+        {
+            Target = target;
+            Member = string.Intern(member);
+        }
+
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context)
+        {
+            if (Target is KeywordExpression ke
+                && ke.Keyword == ExpressionKeyword.Target)
+                return context.Target.GetProperty(Member);
+            if (Target is ParameterExpression pe)
+            {
+                var obj = context.Parameters?.GetObjectParameter(pe.Name);
+                if (obj != null)
+                    return obj.GetProperty(Member);
+            }
+
+            return Target.Evaluate(ref context).GetProperty(Member);
+        }
+
+        protected override string Print()
+        {
+            return "(" + Target.ToString() + ")." + Member;
+        }
+    }
+
+    internal class ParameterExpression : Expression
+    {
+        public string Name { get; }
+        public override ExpressionType Type => ExpressionType.Parameter;
+
+        public ParameterExpression(string name)
+        {
+            Name = name;
+        }
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context)
+        {
+            return context.Parameters?.GetParameter(Name) ?? default;
+        }
+
+        protected override string Print()
+        {
+            return "{" + Name + "}";
+        }
+    }
+
+    internal class KeywordExpression : Expression
+    {
+        public override ExpressionType Type => ExpressionType.Keyword;
+        public ExpressionKeyword Keyword { get; }
+
+        public KeywordExpression(ExpressionKeyword keyword)
+        {
+            Keyword = keyword;
+        }
+
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context)
+        {
+            if (Keyword == ExpressionKeyword.StartingValue)
+                return context.StartingValue;
+            if (Keyword == ExpressionKeyword.CurrentValue)
+                return context.CurrentValue;
+            if (Keyword == ExpressionKeyword.FinalValue)
+                return context.FinalValue;
+            if (Keyword == ExpressionKeyword.Target)
+                // should be handled by MemberAccess
+                return default;
+            if (Keyword == ExpressionKeyword.True)
+                return true;
+            if (Keyword == ExpressionKeyword.False)
+                return false;
+            if (Keyword == ExpressionKeyword.Pi)
+                return (float) Math.PI;
+            return default;
+        }
+
+        protected override string Print()
+        {
+            return "[" + Keyword + "]";
+        }
+    }
+
+    internal class UnaryExpression : Expression
+    {
+        public Expression Parameter { get; }
+        public override ExpressionType Type { get; }
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context)
+        {
+            if (Type == ExpressionType.Not)
+                return !Parameter.Evaluate(ref context);
+            if (Type == ExpressionType.UnaryMinus)
+                return -Parameter.Evaluate(ref context);
+            return default;
+        }
+
+        protected override string Print()
+        {
+            return OperatorName(Type) + Parameter;
+        }
+
+        public UnaryExpression(Expression parameter, ExpressionType type)
+        {
+            Parameter = parameter;
+            Type = type;
+        }
+    }
+    
+    internal class BinaryExpression : Expression
+    {
+        public Expression Left { get; }
+        public Expression Right { get; }
+        public override ExpressionType Type { get; }
+        public override ExpressionVariant Evaluate(ref ExpressionEvaluationContext context)
+        {
+            var left = Left.Evaluate(ref context);
+            var right = Right.Evaluate(ref context);
+            if (Type == ExpressionType.Add)
+                return left + right;
+            if (Type == ExpressionType.Subtract)
+                return left - right;
+            if (Type == ExpressionType.Multiply)
+                return left * right;
+            if (Type == ExpressionType.Divide)
+                return left / right;
+            if (Type == ExpressionType.Remainder)
+                return left % right;
+            if (Type == ExpressionType.MoreThan)
+                return left > right;
+            if (Type == ExpressionType.LessThan)
+                return left < right;
+            if (Type == ExpressionType.MoreThanOrEqual)
+                return left > right;
+            if (Type == ExpressionType.LessThanOrEqual)
+                return left < right;
+            if (Type == ExpressionType.LogicalAnd)
+                return left.And(right);
+            if (Type == ExpressionType.LogicalOr)
+                return left.Or(right);
+            if (Type == ExpressionType.Equals)
+                return left.EqualsTo(right);
+            if (Type == ExpressionType.NotEquals)
+                return left.NotEqualsTo(right);
+            return default;
+        }
+
+        protected override string Print()
+        {
+            return "(" + Left + OperatorName(Type) + Right + ")";
+        }
+
+        public BinaryExpression(Expression left, Expression right, ExpressionType type)
+        {
+            Left = left;
+            Right = right;
+            Type = type;
+        }
+    }
+
+
+
+}

src/Avalonia.Base/Rendering/Composition/Expressions/ExpressionEvaluationContext.cs

@@ -0,0 +1,31 @@
+using System.Collections.Generic;
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal struct ExpressionEvaluationContext
+    {
+        public ExpressionVariant StartingValue { get; set; }
+        public ExpressionVariant CurrentValue { get; set; }
+        public ExpressionVariant FinalValue { get; set; }
+        public IExpressionObject Target { get; set; }
+        public IExpressionParameterCollection Parameters { get; set; }
+        public IExpressionForeignFunctionInterface ForeignFunctionInterface { get; set; }
+    }
+
+    internal interface IExpressionObject
+    {
+        ExpressionVariant GetProperty(string name);
+    }
+
+    internal interface IExpressionParameterCollection
+    {
+        public ExpressionVariant GetParameter(string name);
+
+        public IExpressionObject GetObjectParameter(string name);
+    }
+
+    internal interface IExpressionForeignFunctionInterface
+    {
+        bool Call(string name, IReadOnlyList<ExpressionVariant> arguments, out ExpressionVariant result);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Expressions/ExpressionParseException.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal class ExpressionParseException : Exception
+    {
+        public int Position { get; }
+
+        public ExpressionParseException(string message, int position) : base(message)
+        {
+            Position = position;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Expressions/ExpressionParser.cs

@@ -0,0 +1,298 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+
+// ReSharper disable StringLiteralTypo
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal class ExpressionParser
+    {
+        public static Expression Parse(ReadOnlySpan<char> s)
+        {
+            var p = new TokenParser(s);
+            var parsed = ParseTillTerminator(ref p, "", false, false, out _);
+            p.SkipWhitespace();
+            if (p.Length != 0)
+                throw new ExpressionParseException("Unexpected data ", p.Position);
+            return parsed;
+        }
+
+        private static ReadOnlySpan<char> Dot => ".".AsSpan();
+        static bool TryParseAtomic(ref TokenParser parser, 
+            [MaybeNullWhen(returnValue: false)] out Expression expr)
+        {
+            // We can parse keywords, parameter names and constants
+            expr = null;
+            if (parser.TryParseKeywordLowerCase("this.startingvalue"))
+                expr = new KeywordExpression(ExpressionKeyword.StartingValue);
+            else if(parser.TryParseKeywordLowerCase("this.currentvalue"))
+                expr = new KeywordExpression(ExpressionKeyword.CurrentValue);
+            else if(parser.TryParseKeywordLowerCase("this.finalvalue"))
+                expr = new KeywordExpression(ExpressionKeyword.FinalValue);
+            else if(parser.TryParseKeywordLowerCase("pi"))
+                expr = new KeywordExpression(ExpressionKeyword.Pi);
+            else if(parser.TryParseKeywordLowerCase("true"))
+                expr = new KeywordExpression(ExpressionKeyword.True);
+            else if(parser.TryParseKeywordLowerCase("false"))
+                expr = new KeywordExpression(ExpressionKeyword.False);
+            else if (parser.TryParseKeywordLowerCase("this.target"))
+                expr = new KeywordExpression(ExpressionKeyword.Target);
+
+            if (expr != null)
+                return true;
+
+            if (parser.TryParseIdentifier(out var identifier))
+            {
+                expr = new ParameterExpression(identifier.ToString());
+                return true;
+            }
+
+            if(parser.TryParseFloat(out var scalar))
+            {
+                expr = new ConstantExpression(scalar);
+                return true;
+            }
+
+            return false;
+
+        }
+
+        static bool TryParseOperator(ref TokenParser parser, out ExpressionType op)
+        {
+            op = (ExpressionType) (-1);
+            if (parser.TryConsume("||"))
+                op = ExpressionType.LogicalOr;
+            else if (parser.TryConsume("&&"))
+                op = ExpressionType.LogicalAnd;
+            else if (parser.TryConsume(">="))
+                op = ExpressionType.MoreThanOrEqual;
+            else if (parser.TryConsume("<="))
+                op = ExpressionType.LessThanOrEqual;
+            else if (parser.TryConsume("=="))
+                op = ExpressionType.Equals;
+            else if (parser.TryConsume("!="))
+                op = ExpressionType.NotEquals;
+            else if (parser.TryConsumeAny("+-/*><%".AsSpan(), out var sop))
+            {
+#pragma warning disable CS8509
+                op = sop switch
+#pragma warning restore CS8509
+                {
+                    '+' => ExpressionType.Add,
+                    '-' => ExpressionType.Subtract,
+                    '/' => ExpressionType.Divide,
+                    '*' => ExpressionType.Multiply,
+                    '<' => ExpressionType.LessThan,
+                    '>' => ExpressionType.MoreThan,
+                    '%' => ExpressionType.Remainder
+                };
+            }
+            else
+                return false;
+
+            return true;
+        }
+
+
+        struct ExpressionOperatorGroup
+        {
+            private List<Expression> _expressions;
+            private List<ExpressionType> _operators;
+            private Expression? _first;
+
+            public bool NotEmpty => !Empty;
+            public bool Empty => _expressions == null && _first == null;
+
+            public void AppendFirst(Expression expr)
+            {
+                if (NotEmpty)
+                    throw new InvalidOperationException();
+                _first = expr;
+            }
+
+            public void AppendWithOperator(Expression expr, ExpressionType op)
+            {
+                if (_expressions == null)
+                {
+                    if (_first == null)
+                        throw new InvalidOperationException();
+                    _expressions = new List<Expression>();
+                    _expressions.Add(_first);
+                    _first = null;
+                    _operators = new List<ExpressionType>();
+                }
+                _expressions.Add(expr);
+                _operators.Add(op);
+            }
+
+            // https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/
+            private static readonly ExpressionType[][] OperatorPrecedenceGroups = new[]
+            {
+                // multiplicative
+                new[] {ExpressionType.Multiply, ExpressionType.Divide, ExpressionType.Remainder},
+                // additive
+                new[] {ExpressionType.Add, ExpressionType.Subtract},
+                // relational
+                new[] {ExpressionType.MoreThan, ExpressionType.MoreThanOrEqual, ExpressionType.LessThan, ExpressionType.LessThanOrEqual},
+                // equality
+                new[] {ExpressionType.Equals, ExpressionType.NotEquals},
+                // conditional AND
+                new[] {ExpressionType.LogicalAnd},
+                // conditional OR
+                new[]{ ExpressionType.LogicalOr},
+            };
+
+            private static readonly ExpressionType[][] OperatorPrecedenceGroupsReversed =
+                OperatorPrecedenceGroups.Reverse().ToArray();
+
+            // a*b+c [a,b,c] [*,+], call with (0, 2)
+            // ToExpression(a*b) + ToExpression(c)
+            // a+b*c -> ToExpression(a) + ToExpression(b*c)
+            Expression ToExpression(int from, int to)
+            {
+                if (to - from == 0)
+                    return _expressions[from];
+                
+                if (to - from == 1)
+                    return new BinaryExpression(_expressions[from], _expressions[to], _operators[from]);
+                
+                foreach (var grp in OperatorPrecedenceGroupsReversed)
+                {
+                    for (var c = from; c < to; c++)
+                    {
+                        var currentOperator = _operators[c];
+                        foreach(var operatorFromGroup in grp)
+                            if (currentOperator == operatorFromGroup)
+                            {
+                                // We are dividing the expression right here
+                                var left = ToExpression(from, c);
+                                var right = ToExpression(c + 1, to);
+                                return new BinaryExpression(left, right, currentOperator);
+                            }
+                    }
+                }
+
+                // We shouldn't ever get here, if we are, there is something wrong in the code
+                throw new ExpressionParseException("Expression parsing algorithm bug in ToExpression", 0);
+            }
+
+            public Expression ToExpression()
+            {
+                if (_expressions == null)
+                    return _first ?? throw new InvalidOperationException();
+                return ToExpression(0, _expressions.Count - 1);
+            }
+        }
+
+        static Expression ParseTillTerminator(ref TokenParser parser, string terminatorChars, 
+            bool throwOnTerminator,
+            bool throwOnEnd,
+            out char? token)
+        {
+            ExpressionOperatorGroup left = default;
+            token = null;
+            while (true)
+            {
+                if (parser.TryConsumeAny(terminatorChars.AsSpan(), out var consumedToken))
+                {
+                    if (throwOnTerminator || left.Empty)
+                        throw new ExpressionParseException($"Unexpected '{token}'", parser.Position - 1);
+                    token = consumedToken;
+                    return left.ToExpression();
+                }
+                parser.SkipWhitespace();
+                if (parser.Length == 0)
+                {
+                    if (throwOnEnd || left.Empty)
+                        throw new ExpressionParseException("Unexpected end of  expression", parser.Position);
+                    return left.ToExpression();
+                }
+                
+                ExpressionType? op = null;
+                if (left.NotEmpty)
+                {
+                    if (parser.TryConsume('?'))
+                    {
+                        var truePart = ParseTillTerminator(ref parser, ":",
+                            false, true, out _);
+                        // pass through the current parsing rules to consume the rest
+                        var falsePart = ParseTillTerminator(ref parser, terminatorChars, throwOnTerminator, throwOnEnd,
+                            out token);
+                        
+                        return new ConditionalExpression(left.ToExpression(), truePart, falsePart);
+                    }
+                    
+                    // We expect a binary operator here
+                    if (!TryParseOperator(ref parser, out var sop))
+                        throw new ExpressionParseException("Unexpected token", parser.Position);
+                    op = sop;
+                }
+                
+                // We expect an expression to be parsed (either due to expecting a binary operator or parsing the first part
+                var applyNegation = false;
+                while (parser.TryConsume('!')) 
+                    applyNegation = !applyNegation;
+
+                var applyUnaryMinus = false;
+                while (parser.TryConsume('-')) 
+                    applyUnaryMinus = !applyUnaryMinus;
+
+                Expression? parsed;
+                
+                if (parser.TryConsume('(')) 
+                    parsed = ParseTillTerminator(ref parser, ")", false, true, out _);
+                else if (parser.TryParseCall(out var functionName))
+                {
+                    var parameterList = new List<Expression>();
+                    while (true)
+                    {
+                        parameterList.Add(ParseTillTerminator(ref parser, ",)", false, true, out var closingToken));
+                        if (closingToken == ')')
+                            break;
+                        if (closingToken != ',')
+                            throw new ExpressionParseException("Unexpected end of the expression", parser.Position);
+                    }
+
+                    parsed = new FunctionCallExpression(functionName.ToString(), parameterList);
+                }
+                else if (TryParseAtomic(ref parser, out parsed))
+                {
+                    // do nothing
+                }
+                else
+                    throw new ExpressionParseException("Unexpected token", parser.Position);
+
+                
+                // Parse any following member accesses
+                while (parser.TryConsume('.'))
+                {
+                    if(!parser.TryParseIdentifier(out var memberName))
+                        throw new ExpressionParseException("Unexpected token", parser.Position);
+
+                    parsed = new MemberAccessExpression(parsed, memberName.ToString());
+                }
+
+                // Apply ! operator
+                if (applyNegation)
+                    parsed = new UnaryExpression(parsed, ExpressionType.Not);
+
+                if (applyUnaryMinus)
+                {
+                    if(parsed is ConstantExpression constexpr)
+                        parsed = new ConstantExpression(-constexpr.Constant);
+                    else parsed = new UnaryExpression(parsed, ExpressionType.UnaryMinus);
+                }
+
+                if (left.Empty)
+                    left.AppendFirst(parsed);
+                else
+                    left.AppendWithOperator(parsed, op!.Value);
+            }
+            
+            
+            
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Expressions/ExpressionVariant.cs

@@ -0,0 +1,739 @@
+using System;
+using System.Globalization;
+using System.Numerics;
+using System.Runtime.InteropServices;
+using Avalonia.Media;
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal enum VariantType
+    {
+        Invalid,
+        Boolean,
+        Scalar,
+        Double,
+        Vector2,
+        Vector3,
+        Vector4,
+        AvaloniaMatrix,
+        Matrix3x2,
+        Matrix4x4,
+        Quaternion,
+        Color
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    internal struct ExpressionVariant
+    {
+        [FieldOffset(0)] public VariantType Type;
+
+        [FieldOffset(4)] public bool Boolean;
+        [FieldOffset(4)] public float Scalar;
+        [FieldOffset(4)] public double Double;
+        [FieldOffset(4)] public Vector2 Vector2;
+        [FieldOffset(4)] public Vector3 Vector3;
+        [FieldOffset(4)] public Vector4 Vector4;
+        [FieldOffset(4)] public Matrix AvaloniaMatrix;
+        [FieldOffset(4)] public Matrix3x2 Matrix3x2;
+        [FieldOffset(4)] public Matrix4x4 Matrix4x4;
+        [FieldOffset(4)] public Quaternion Quaternion;
+        [FieldOffset(4)] public Color Color;
+        
+
+        public ExpressionVariant GetProperty(string property)
+        {
+            if (Type == VariantType.Vector2)
+            {
+                if (ReferenceEquals(property, "X"))
+                    return Vector2.X;
+                if (ReferenceEquals(property, "Y"))
+                    return Vector2.Y;
+                return default;
+            }
+
+            if (Type == VariantType.Vector3)
+            {
+                if (ReferenceEquals(property, "X"))
+                    return Vector3.X;
+                if (ReferenceEquals(property, "Y"))
+                    return Vector3.Y;
+                if (ReferenceEquals(property, "Z"))
+                    return Vector3.Z;
+                if(ReferenceEquals(property, "XY"))
+                    return new Vector2(Vector3.X, Vector3.Y);
+                if(ReferenceEquals(property, "YX"))
+                    return new Vector2(Vector3.Y, Vector3.X);
+                if(ReferenceEquals(property, "XZ"))
+                    return new Vector2(Vector3.X, Vector3.Z);
+                if(ReferenceEquals(property, "ZX"))
+                    return new Vector2(Vector3.Z, Vector3.X);
+                if(ReferenceEquals(property, "YZ"))
+                    return new Vector2(Vector3.Y, Vector3.Z);
+                if(ReferenceEquals(property, "ZY"))
+                    return new Vector2(Vector3.Z, Vector3.Y);
+                return default;
+            }
+
+            if (Type == VariantType.Vector4)
+            {
+                if (ReferenceEquals(property, "X"))
+                    return Vector4.X;
+                if (ReferenceEquals(property, "Y"))
+                    return Vector4.Y;
+                if (ReferenceEquals(property, "Z"))
+                    return Vector4.Z;
+                if (ReferenceEquals(property, "W"))
+                    return Vector4.W;
+                return default;
+            }
+
+            if (Type == VariantType.Matrix3x2)
+            {
+                if (ReferenceEquals(property, "M11"))
+                    return Matrix3x2.M11;
+                if (ReferenceEquals(property, "M12"))
+                    return Matrix3x2.M12;
+                if (ReferenceEquals(property, "M21"))
+                    return Matrix3x2.M21;
+                if (ReferenceEquals(property, "M22"))
+                    return Matrix3x2.M22;
+                if (ReferenceEquals(property, "M31"))
+                    return Matrix3x2.M31;
+                if (ReferenceEquals(property, "M32"))
+                    return Matrix3x2.M32;
+                return default;
+            }
+            
+            if (Type == VariantType.AvaloniaMatrix)
+            {
+                if (ReferenceEquals(property, "M11"))
+                    return AvaloniaMatrix.M11;
+                if (ReferenceEquals(property, "M12"))
+                    return AvaloniaMatrix.M12;
+                if (ReferenceEquals(property, "M21"))
+                    return AvaloniaMatrix.M21;
+                if (ReferenceEquals(property, "M22"))
+                    return AvaloniaMatrix.M22;
+                if (ReferenceEquals(property, "M31"))
+                    return AvaloniaMatrix.M31;
+                if (ReferenceEquals(property, "M32"))
+                    return AvaloniaMatrix.M32;
+                return default;
+            }
+
+            if (Type == VariantType.Matrix4x4)
+            {
+                if (ReferenceEquals(property, "M11"))
+                    return Matrix4x4.M11;
+                if (ReferenceEquals(property, "M12"))
+                    return Matrix4x4.M12;
+                if (ReferenceEquals(property, "M13"))
+                    return Matrix4x4.M13;
+                if (ReferenceEquals(property, "M14"))
+                    return Matrix4x4.M14;
+                if (ReferenceEquals(property, "M21"))
+                    return Matrix4x4.M21;
+                if (ReferenceEquals(property, "M22"))
+                    return Matrix4x4.M22;
+                if (ReferenceEquals(property, "M23"))
+                    return Matrix4x4.M23;
+                if (ReferenceEquals(property, "M24"))
+                    return Matrix4x4.M24;
+                if (ReferenceEquals(property, "M31"))
+                    return Matrix4x4.M31;
+                if (ReferenceEquals(property, "M32"))
+                    return Matrix4x4.M32;
+                if (ReferenceEquals(property, "M33"))
+                    return Matrix4x4.M33;
+                if (ReferenceEquals(property, "M34"))
+                    return Matrix4x4.M34;
+                if (ReferenceEquals(property, "M41"))
+                    return Matrix4x4.M41;
+                if (ReferenceEquals(property, "M42"))
+                    return Matrix4x4.M42;
+                if (ReferenceEquals(property, "M43"))
+                    return Matrix4x4.M43;
+                if (ReferenceEquals(property, "M44"))
+                    return Matrix4x4.M44;
+                return default;
+            }
+
+            if (Type == VariantType.Quaternion)
+            {
+                if (ReferenceEquals(property, "X"))
+                    return Quaternion.X;
+                if (ReferenceEquals(property, "Y"))
+                    return Quaternion.Y;
+                if (ReferenceEquals(property, "Z"))
+                    return Quaternion.Z;
+                if (ReferenceEquals(property, "W"))
+                    return Quaternion.W;
+                return default;
+            }
+            
+            if (Type == VariantType.Color)
+            {
+                if (ReferenceEquals(property, "A"))
+                    return Color.A;
+                if (ReferenceEquals(property, "R"))
+                    return Color.R;
+                if (ReferenceEquals(property, "G"))
+                    return Color.G;
+                if (ReferenceEquals(property, "B"))
+                    return Color.B;
+                return default;
+            }
+
+            return default;
+        }
+
+        public static implicit operator ExpressionVariant(bool value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Boolean,
+                Boolean = value
+            };
+
+        public static implicit operator ExpressionVariant(float scalar) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Scalar,
+                Scalar = scalar
+            };
+        
+        public static implicit operator ExpressionVariant(double d) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Double,
+                Double = d
+            };
+
+
+        public static implicit operator ExpressionVariant(Vector2 value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Vector2,
+                Vector2 = value
+            };
+
+
+        public static implicit operator ExpressionVariant(Vector3 value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Vector3,
+                Vector3 = value
+            };
+
+
+        public static implicit operator ExpressionVariant(Vector4 value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Vector4,
+                Vector4 = value
+            };
+
+        public static implicit operator ExpressionVariant(Matrix3x2 value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Matrix3x2,
+                Matrix3x2 = value
+            };
+        
+        public static implicit operator ExpressionVariant(Matrix value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Matrix3x2,
+                AvaloniaMatrix = value
+            };
+
+        public static implicit operator ExpressionVariant(Matrix4x4 value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Matrix4x4,
+                Matrix4x4 = value
+            };
+
+        public static implicit operator ExpressionVariant(Quaternion value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Quaternion,
+                Quaternion = value
+            };
+        
+        public static implicit operator ExpressionVariant(Avalonia.Media.Color value) =>
+            new ExpressionVariant
+            {
+                Type = VariantType.Color,
+                Color = value
+            };
+
+        public static ExpressionVariant operator +(ExpressionVariant left, ExpressionVariant right)
+        {
+            if (left.Type != right.Type || left.Type == VariantType.Invalid)
+                return default;
+
+            if (left.Type == VariantType.Scalar)
+                return left.Scalar + right.Scalar;
+            
+            if (left.Type == VariantType.Double)
+                return left.Double + right.Double;
+
+            if (left.Type == VariantType.Vector2)
+                return left.Vector2 + right.Vector2;
+
+            if (left.Type == VariantType.Vector3)
+                return left.Vector3 + right.Vector3;
+
+            if (left.Type == VariantType.Vector4)
+                return left.Vector4 + right.Vector4;
+            
+            if (left.Type == VariantType.Matrix3x2)
+                return left.Matrix3x2 + right.Matrix3x2;
+            
+            if (left.Type == VariantType.AvaloniaMatrix)
+                return left.AvaloniaMatrix + right.AvaloniaMatrix;
+
+            if (left.Type == VariantType.Matrix4x4)
+                return left.Matrix4x4 + right.Matrix4x4;
+            
+            if (left.Type == VariantType.Quaternion)
+                return left.Quaternion + right.Quaternion;
+            
+            return default;
+        }
+
+        public static ExpressionVariant operator -(ExpressionVariant left, ExpressionVariant right)
+        {
+            if (left.Type != right.Type || left.Type == VariantType.Invalid)
+                return default;
+
+            if (left.Type == VariantType.Scalar)
+                return left.Scalar - right.Scalar;
+            
+            if (left.Type == VariantType.Double)
+                return left.Double - right.Double;
+
+            if (left.Type == VariantType.Vector2)
+                return left.Vector2 - right.Vector2;
+
+            if (left.Type == VariantType.Vector3)
+                return left.Vector3 - right.Vector3;
+
+            if (left.Type == VariantType.Vector4)
+                return left.Vector4 - right.Vector4;
+            
+            if (left.Type == VariantType.Matrix3x2)
+                return left.Matrix3x2 - right.Matrix3x2;
+            
+            if (left.Type == VariantType.AvaloniaMatrix)
+                return left.AvaloniaMatrix - right.AvaloniaMatrix;
+
+            if (left.Type == VariantType.Matrix4x4)
+                return left.Matrix4x4 - right.Matrix4x4;
+            
+            if (left.Type == VariantType.Quaternion)
+                return left.Quaternion - right.Quaternion;
+
+            return default;
+        }
+
+        public static ExpressionVariant operator -(ExpressionVariant left)
+        {
+
+            if (left.Type == VariantType.Scalar)
+                return -left.Scalar;
+            
+            if (left.Type == VariantType.Double)
+                return -left.Double;
+
+            if (left.Type == VariantType.Vector2)
+                return -left.Vector2;
+
+            if (left.Type == VariantType.Vector3)
+                return -left.Vector3;
+
+            if (left.Type == VariantType.Vector4)
+                return -left.Vector4;
+            
+            if (left.Type == VariantType.Matrix3x2)
+                return -left.Matrix3x2;
+            
+            if (left.Type == VariantType.AvaloniaMatrix)
+                return -left.AvaloniaMatrix;
+            
+            if (left.Type == VariantType.Matrix4x4)
+                return -left.Matrix4x4;
+
+            if (left.Type == VariantType.Quaternion)
+                return -left.Quaternion;
+
+            return default;
+        }
+
+        public static ExpressionVariant operator *(ExpressionVariant left, ExpressionVariant right)
+        {
+            if (left.Type == VariantType.Invalid || right.Type == VariantType.Invalid)
+                return default;
+
+            if (left.Type == VariantType.Scalar && right.Type == VariantType.Scalar)
+                return left.Scalar * right.Scalar;
+            
+            if (left.Type == VariantType.Double && right.Type == VariantType.Double)
+                return left.Double * right.Double;
+
+            if (left.Type == VariantType.Vector2 && right.Type == VariantType.Vector2)
+                return left.Vector2 * right.Vector2;
+
+            if (left.Type == VariantType.Vector2 && right.Type == VariantType.Scalar)
+                return left.Vector2 * right.Scalar;
+
+            if (left.Type == VariantType.Vector3 && right.Type == VariantType.Vector3)
+                return left.Vector3 * right.Vector3;
+
+            if (left.Type == VariantType.Vector3 && right.Type == VariantType.Scalar)
+                return left.Vector3 * right.Scalar;
+
+            if (left.Type == VariantType.Vector4 && right.Type == VariantType.Vector4)
+                return left.Vector4 * right.Vector4;
+
+            if (left.Type == VariantType.Vector4 && right.Type == VariantType.Scalar)
+                return left.Vector4 * right.Scalar;
+            
+            if (left.Type == VariantType.Matrix3x2 && right.Type == VariantType.Matrix3x2)
+                return left.Matrix3x2 * right.Matrix3x2;
+
+            if (left.Type == VariantType.Matrix3x2 && right.Type == VariantType.Scalar)
+                return left.Matrix3x2 * right.Scalar;
+            
+            if (left.Type == VariantType.AvaloniaMatrix && right.Type == VariantType.AvaloniaMatrix)
+                return left.AvaloniaMatrix * right.AvaloniaMatrix;
+
+            if (left.Type == VariantType.AvaloniaMatrix && right.Type == VariantType.Scalar)
+                return left.AvaloniaMatrix * (double)right.Scalar;
+            
+            if (left.Type == VariantType.AvaloniaMatrix && right.Type == VariantType.Double)
+                return left.AvaloniaMatrix * right.Double;
+            
+            if (left.Type == VariantType.Matrix4x4 && right.Type == VariantType.Matrix4x4)
+                return left.Matrix4x4 * right.Matrix4x4;
+
+            if (left.Type == VariantType.Matrix4x4 && right.Type == VariantType.Scalar)
+                return left.Matrix4x4 * right.Scalar;
+            
+            if (left.Type == VariantType.Quaternion && right.Type == VariantType.Quaternion)
+                return left.Quaternion * right.Quaternion;
+
+            if (left.Type == VariantType.Quaternion && right.Type == VariantType.Scalar)
+                return left.Quaternion * right.Scalar;
+
+            return default;
+        }
+
+        public static ExpressionVariant operator /(ExpressionVariant left, ExpressionVariant right)
+        {
+            if (left.Type == VariantType.Invalid || right.Type == VariantType.Invalid)
+                return default;
+
+            if (left.Type == VariantType.Scalar && right.Type == VariantType.Scalar)
+                return left.Scalar / right.Scalar;
+            
+            if (left.Type == VariantType.Double && right.Type == VariantType.Double)
+                return left.Double / right.Double;
+
+            if (left.Type == VariantType.Vector2 && right.Type == VariantType.Vector2)
+                return left.Vector2 / right.Vector2;
+
+            if (left.Type == VariantType.Vector2 && right.Type == VariantType.Scalar)
+                return left.Vector2 / right.Scalar;
+
+            if (left.Type == VariantType.Vector3 && right.Type == VariantType.Vector3)
+                return left.Vector3 / right.Vector3;
+
+            if (left.Type == VariantType.Vector3 && right.Type == VariantType.Scalar)
+                return left.Vector3 / right.Scalar;
+
+            if (left.Type == VariantType.Vector4 && right.Type == VariantType.Vector4)
+                return left.Vector4 / right.Vector4;
+
+            if (left.Type == VariantType.Vector4 && right.Type == VariantType.Scalar)
+                return left.Vector4 / right.Scalar;
+            
+            if (left.Type == VariantType.Quaternion && right.Type == VariantType.Quaternion)
+                return left.Quaternion / right.Quaternion;
+
+            return default;
+        }
+
+        public ExpressionVariant EqualsTo(ExpressionVariant right)
+        {
+            if (Type != right.Type || Type == VariantType.Invalid)
+                return default;
+
+            if (Type == VariantType.Scalar)
+                return Scalar == right.Scalar;
+            
+            
+            if (Type == VariantType.Double)
+                return Double == right.Double;
+
+            if (Type == VariantType.Vector2)
+                return Vector2 == right.Vector2;
+
+            if (Type == VariantType.Vector3)
+                return Vector3 == right.Vector3;
+
+            if (Type == VariantType.Vector4)
+                return Vector4 == right.Vector4;
+
+            if (Type == VariantType.Boolean)
+                return Boolean == right.Boolean;
+
+            if (Type == VariantType.Matrix3x2)
+                return Matrix3x2 == right.Matrix3x2;
+            
+            if (Type == VariantType.AvaloniaMatrix)
+                return AvaloniaMatrix == right.AvaloniaMatrix;
+
+            if (Type == VariantType.Matrix4x4)
+                return Matrix4x4 == right.Matrix4x4;
+
+            if (Type == VariantType.Quaternion)
+                return Quaternion == right.Quaternion;
+            
+            return default;
+        }
+
+        public ExpressionVariant NotEqualsTo(ExpressionVariant right)
+        {
+            var r = EqualsTo(right);
+            if (r.Type == VariantType.Boolean)
+                return !r.Boolean;
+            return default;
+        }
+
+        public static ExpressionVariant operator !(ExpressionVariant v)
+        {
+            if (v.Type == VariantType.Boolean)
+                return !v.Boolean;
+            return default;
+        }
+
+        public static ExpressionVariant operator %(ExpressionVariant left, ExpressionVariant right)
+        {
+            if (left.Type == VariantType.Scalar && right.Type == VariantType.Scalar)
+                return left.Scalar % right.Scalar;
+            if (left.Type == VariantType.Double && right.Type == VariantType.Double)
+                return left.Double % right.Double;
+            return default;
+        }
+
+        public static ExpressionVariant operator <(ExpressionVariant left, ExpressionVariant right)
+        {
+            if (left.Type == VariantType.Scalar && right.Type == VariantType.Scalar)
+                return left.Scalar < right.Scalar;
+            if (left.Type == VariantType.Double && right.Type == VariantType.Double)
+                return left.Double < right.Double;
+            return default;
+        }
+
+        public static ExpressionVariant operator >(ExpressionVariant left, ExpressionVariant right)
+        {
+            if (left.Type == VariantType.Scalar && right.Type == VariantType.Scalar)
+                return left.Scalar > right.Scalar;
+            
+            if (left.Type == VariantType.Double && right.Type == VariantType.Double)
+                return left.Double > right.Double;
+            return default;
+        }
+
+        public ExpressionVariant And(ExpressionVariant right)
+        {
+            if (Type == VariantType.Boolean && right.Type == VariantType.Boolean)
+                return Boolean && right.Boolean;
+            return default;
+        }
+
+        public ExpressionVariant Or(ExpressionVariant right)
+        {
+            if (Type == VariantType.Boolean && right.Type == VariantType.Boolean)
+                return Boolean && right.Boolean;
+            return default;
+        }
+
+        public bool TryCast<T>(out T res) where T : struct
+        {
+            if (typeof(T) == typeof(bool))
+            {
+                if (Type == VariantType.Boolean)
+                {
+                    res = (T) (object) Boolean;
+                    return true;
+                }
+            }
+
+            if (typeof(T) == typeof(float))
+            {
+                if (Type == VariantType.Scalar)
+                {
+                    res = (T) (object) Scalar;
+                    return true;
+                }
+            }
+            
+            if (typeof(T) == typeof(double))
+            {
+                if (Type == VariantType.Double)
+                {
+                    res = (T) (object) Double;
+                    return true;
+                }
+            }
+
+            if (typeof(T) == typeof(Vector2))
+            {
+                if (Type == VariantType.Vector2)
+                {
+                    res = (T) (object) Vector2;
+                    return true;
+                }
+            }
+
+            if (typeof(T) == typeof(Vector3))
+            {
+                if (Type == VariantType.Vector3)
+                {
+                    res = (T) (object) Vector3;
+                    return true;
+                }
+            }
+
+            if (typeof(T) == typeof(Vector4))
+            {
+                if (Type == VariantType.Vector4)
+                {
+                    res = (T) (object) Vector4;
+                    return true;
+                }
+            }
+
+            if (typeof(T) == typeof(Matrix3x2))
+            {
+                if (Type == VariantType.Matrix3x2)
+                {
+                    res = (T) (object) Matrix3x2;
+                    return true;
+                }
+            }
+            
+            if (typeof(T) == typeof(Matrix))
+            {
+                if (Type == VariantType.AvaloniaMatrix)
+                {
+                    res = (T) (object) Matrix3x2;
+                    return true;
+                }
+            }
+
+            if (typeof(T) == typeof(Matrix4x4))
+            {
+                if (Type == VariantType.Matrix4x4)
+                {
+                    res = (T) (object) Matrix4x4;
+                    return true;
+                }
+            }
+
+            if (typeof(T) == typeof(Quaternion))
+            {
+                if (Type == VariantType.Quaternion)
+                {
+                    res = (T) (object) Quaternion;
+                    return true;
+                }
+            }
+            
+            if (typeof(T) == typeof(Avalonia.Media.Color))
+            {
+                if (Type == VariantType.Color)
+                {
+                    res = (T) (object) Color;
+                    return true;
+                }
+            }
+
+            res = default(T);
+            return false;
+        }
+
+        public static ExpressionVariant Create<T>(T v) where T : struct
+        {
+            if (typeof(T) == typeof(bool))
+                return (bool) (object) v;
+
+            if (typeof(T) == typeof(float))
+                return (float) (object) v;
+
+            if (typeof(T) == typeof(Vector2))
+                return (Vector2) (object) v;
+
+            if (typeof(T) == typeof(Vector3))
+                return (Vector3) (object) v;
+
+            if (typeof(T) == typeof(Vector4))
+                return (Vector4) (object) v;
+
+            if (typeof(T) == typeof(Matrix3x2))
+                return (Matrix3x2) (object) v;
+            
+            if (typeof(T) == typeof(Matrix))
+                return (Matrix) (object) v;
+
+            if (typeof(T) == typeof(Matrix4x4))
+                return (Matrix4x4) (object) v;
+
+            if (typeof(T) == typeof(Quaternion))
+                return (Quaternion) (object) v;
+            
+            if (typeof(T) == typeof(Avalonia.Media.Color))
+                return (Avalonia.Media.Color) (object) v;
+
+            throw new ArgumentException("Invalid variant type: " + typeof(T));
+        }
+
+        public T CastOrDefault<T>() where T : struct
+        {
+            TryCast<T>(out var r);
+            return r;
+        }
+
+        public override string ToString()
+        {
+            if (Type == VariantType.Boolean)
+                return Boolean.ToString();
+            if (Type == VariantType.Scalar)
+                return Scalar.ToString(CultureInfo.InvariantCulture);
+            if (Type == VariantType.Double)
+                return Double.ToString(CultureInfo.InvariantCulture);
+            if (Type == VariantType.Vector2)
+                return Vector2.ToString();
+            if (Type == VariantType.Vector3)
+                return Vector3.ToString();
+            if (Type == VariantType.Vector4)
+                return Vector4.ToString();
+            if (Type == VariantType.Quaternion)
+                return Quaternion.ToString();
+            if (Type == VariantType.Matrix3x2)
+                return Matrix3x2.ToString();
+            if (Type == VariantType.AvaloniaMatrix)
+                return AvaloniaMatrix.ToString();
+            if (Type == VariantType.Matrix4x4)
+                return Matrix4x4.ToString();
+            if (Type == VariantType.Color)
+                return Color.ToString();
+            if (Type == VariantType.Invalid)
+                return "Invalid";
+            return "Unknown";
+        }
+    }
+
+}

src/Avalonia.Base/Rendering/Composition/Expressions/TokenParser.cs

@@ -0,0 +1,256 @@
+using System;
+using System.Globalization;
+
+namespace Avalonia.Rendering.Composition.Expressions
+{
+    internal ref struct TokenParser
+    {
+        private ReadOnlySpan<char> _s;
+        public int Position { get; private set; }
+        public TokenParser(ReadOnlySpan<char> s)
+        {
+            _s = s;
+            Position = 0;
+        }
+
+        public void SkipWhitespace()
+        {
+            while (true)
+            {
+                if (_s.Length > 0 && char.IsWhiteSpace(_s[0]))
+                    Advance(1);
+                else
+                    return;
+            }
+        }
+
+        static bool IsAlphaNumeric(char ch) => (ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'z') ||
+                                               (ch >= 'A' && ch <= 'Z');
+
+        public bool TryConsume(char c)
+        {
+            SkipWhitespace();
+            if (_s.Length == 0 || _s[0] != c)
+                return false;
+
+            Advance(1);
+            return true;
+        }
+        public bool TryConsume(string s)
+        {
+            SkipWhitespace();
+            if (_s.Length < s.Length)
+                return false;
+            for (var c = 0; c < s.Length; c++)
+            {
+                if (_s[c] != s[c])
+                    return false;
+            }
+
+            Advance(s.Length);
+            return true;
+        }
+        
+        public bool TryConsumeAny(ReadOnlySpan<char> chars, out char token)
+        {
+            SkipWhitespace();
+            token = default;
+            if (_s.Length == 0)
+                return false;
+
+            foreach (var c in chars)
+            {
+                if (c == _s[0])
+                {
+                    token = c;
+                    Advance(1);
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        
+        public bool TryParseKeyword(string keyword)
+        {
+            SkipWhitespace();
+            if (keyword.Length > _s.Length)
+                return false;
+            for(var c=0; c<keyword.Length;c++)
+                if (keyword[c] != _s[c])
+                    return false;
+
+            if (_s.Length > keyword.Length && IsAlphaNumeric(_s[keyword.Length]))
+                return false;
+
+            Advance(keyword.Length);
+            return true;
+        }
+        
+        public bool TryParseKeywordLowerCase(string keywordInLowerCase)
+        {
+            SkipWhitespace();
+            if (keywordInLowerCase.Length > _s.Length)
+                return false;
+            for(var c=0; c<keywordInLowerCase.Length;c++)
+                if (keywordInLowerCase[c] != char.ToLowerInvariant(_s[c]))
+                    return false;
+            
+            if (_s.Length > keywordInLowerCase.Length && IsAlphaNumeric(_s[keywordInLowerCase.Length]))
+                return false;
+            
+            Advance(keywordInLowerCase.Length);
+            return true;
+        }
+
+        public void Advance(int c)
+        {
+            _s = _s.Slice(c);
+            Position += c;
+        }
+
+        public int Length => _s.Length;
+
+        public bool TryParseIdentifier(ReadOnlySpan<char> extraValidChars, out ReadOnlySpan<char> res)
+        {
+            res = ReadOnlySpan<char>.Empty;
+            SkipWhitespace();
+            if (_s.Length == 0)
+                return false;
+            var first = _s[0];
+            if (!((first >= 'a' && first <= 'z') || (first >= 'A' && first <= 'Z')))
+                return false;
+            int len = 1;
+            for (var c = 1; c < _s.Length; c++)
+            {
+                var ch = _s[c];
+                if (IsAlphaNumeric(ch))
+                    len++;
+                else
+                {
+                    var found = false;
+                    foreach(var vc in extraValidChars)
+                        if (vc == ch)
+                        {
+                            found = true;
+                            break;
+                        }
+
+                    if (found)
+                        len++;
+                    else
+                        break;
+                }
+            }
+
+            res = _s.Slice(0, len);
+            Advance(len);
+            return true;
+        }
+        
+        public bool TryParseIdentifier(out ReadOnlySpan<char> res)
+        {
+            res = ReadOnlySpan<char>.Empty;
+            SkipWhitespace();
+            if (_s.Length == 0)
+                return false;
+            var first = _s[0];
+            if (!((first >= 'a' && first <= 'z') || (first >= 'A' && first <= 'Z')))
+                return false;
+            int len = 1;
+            for (var c = 1; c < _s.Length; c++)
+            {
+                var ch = _s[c];
+                if (IsAlphaNumeric(ch))
+                    len++;
+                else
+                    break;
+            }
+
+            res = _s.Slice(0, len);
+            Advance(len);
+            return true;
+        }
+        
+        public bool TryParseCall(out ReadOnlySpan<char> res)
+        {
+            res = ReadOnlySpan<char>.Empty;
+            SkipWhitespace();
+            if (_s.Length == 0)
+                return false;
+            var first = _s[0];
+            if (!((first >= 'a' && first <= 'z') || (first >= 'A' && first <= 'Z')))
+                return false;
+            int len = 1;
+            for (var c = 1; c < _s.Length; c++)
+            {
+                var ch = _s[c];
+                if ((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch<= 'Z') || ch == '.')
+                    len++;
+                else
+                    break;
+            }
+            
+            res = _s.Slice(0, len);
+
+            // Find '('
+            for (var c = len; c < _s.Length; c++)
+            {
+                if(char.IsWhiteSpace(_s[c]))
+                    continue;
+                if(_s[c]=='(')
+                {
+                    Advance(c + 1);
+                    return true;
+                }
+
+                return false;
+
+            }
+
+            return false;
+
+        }
+        
+        
+        public bool TryParseFloat(out float res)
+        {
+            res = 0;
+            SkipWhitespace();
+            if (_s.Length == 0)
+                return false;
+            
+            var len = 0;
+            var dotCount = 0;
+            for (var c = 0; c < _s.Length; c++)
+            {
+                var ch = _s[c];
+                if (ch >= '0' && ch <= '9')
+                    len = c + 1;
+                else if (ch == '.' && dotCount == 0)
+                {
+                    len = c + 1;
+                    dotCount++;
+                }
+                else
+                    break;
+            }
+
+            var span = _s.Slice(0, len);
+
+#if NETSTANDARD2_0
+            if (!float.TryParse(span.ToString(), NumberStyles.Number, CultureInfo.InvariantCulture, out res))
+                return false;
+#else
+            if (!float.TryParse(span, NumberStyles.Number, CultureInfo.InvariantCulture, out res))
+                return false;
+#endif
+            Advance(len);
+            return true;
+        }
+
+        public override string ToString() => _s.ToString();
+
+    }
+}

src/Avalonia.Base/Rendering/Composition/ICompositionSurface.cs

@@ -0,0 +1,9 @@
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition
+{
+    public interface ICompositionSurface
+    {
+        internal ServerCompositionSurface Server { get; }
+    }
+}

src/Avalonia.Base/Rendering/Composition/MatrixUtils.cs

@@ -0,0 +1,46 @@
+using System.Numerics;
+
+namespace Avalonia.Rendering.Composition
+{
+    static class MatrixUtils
+    {
+        public static Matrix4x4 ComputeTransform(Vector2 size, Vector2 anchorPoint, Vector3 centerPoint,
+            Matrix4x4 transformMatrix, Vector3 scale, float rotationAngle, Quaternion orientation, Vector3 offset)
+        {
+            // The math here follows the *observed* UWP behavior since there are no docs on how it's supposed to work
+            
+            var anchor = size * anchorPoint;
+            var  mat = Matrix4x4.CreateTranslation(-anchor.X, -anchor.Y, 0);
+
+            var center = new Vector3(centerPoint.X, centerPoint.Y, centerPoint.Z);
+
+            if (!transformMatrix.IsIdentity)
+                mat = transformMatrix * mat;
+
+
+            if (scale != new Vector3(1, 1, 1))
+                mat *= Matrix4x4.CreateScale(scale, center);
+
+            //TODO: RotationAxis support
+            if (rotationAngle != 0)
+                mat *= Matrix4x4.CreateRotationZ(rotationAngle, center);
+
+            if (orientation != Quaternion.Identity)
+            {
+                if (centerPoint != default)
+                {
+                    mat *= Matrix4x4.CreateTranslation(-center)
+                           * Matrix4x4.CreateFromQuaternion(orientation)
+                           * Matrix4x4.CreateTranslation(center);
+                }
+                else
+                    mat *= Matrix4x4.CreateFromQuaternion(orientation);
+            }
+
+            if (offset != default)
+                mat *= Matrix4x4.CreateTranslation(offset);
+
+            return mat;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/DrawingContextProxy.cs

@@ -0,0 +1,142 @@
+using System.Numerics;
+using Avalonia.Media;
+using Avalonia.Media.Imaging;
+using Avalonia.Platform;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.Utilities;
+
+namespace Avalonia.Rendering.Composition.Server;
+
+internal class CompositorDrawingContextProxy : IDrawingContextImpl
+{
+    private IDrawingContextImpl _impl;
+
+    public CompositorDrawingContextProxy(IDrawingContextImpl impl)
+    {
+        _impl = impl;
+    }
+
+    public Matrix PreTransform { get; set; } = Matrix.Identity;
+    
+    public void Dispose()
+    {
+        _impl.Dispose();
+    }
+
+    Matrix _transform;    
+    public Matrix Transform
+    {
+        get => _transform;
+        set => _impl.Transform = PreTransform * (_transform = value);
+    }
+
+    public void Clear(Color color)
+    {
+        _impl.Clear(color);
+    }
+
+    public void DrawBitmap(IRef<IBitmapImpl> source, double opacity, Rect sourceRect, Rect destRect,
+        BitmapInterpolationMode bitmapInterpolationMode = BitmapInterpolationMode.Default)
+    {
+        _impl.DrawBitmap(source, opacity, sourceRect, destRect, bitmapInterpolationMode);
+    }
+
+    public void DrawBitmap(IRef<IBitmapImpl> source, IBrush opacityMask, Rect opacityMaskRect, Rect destRect)
+    {
+        _impl.DrawBitmap(source, opacityMask, opacityMaskRect, destRect);
+    }
+
+    public void DrawLine(IPen pen, Point p1, Point p2)
+    {
+        _impl.DrawLine(pen, p1, p2);
+    }
+
+    public void DrawGeometry(IBrush? brush, IPen? pen, IGeometryImpl geometry)
+    {
+        _impl.DrawGeometry(brush, pen, geometry);
+    }
+
+    public void DrawRectangle(IBrush? brush, IPen? pen, RoundedRect rect, BoxShadows boxShadows = default)
+    {
+        _impl.DrawRectangle(brush, pen, rect, boxShadows);
+    }
+
+    public void DrawEllipse(IBrush? brush, IPen? pen, Rect rect)
+    {
+        _impl.DrawEllipse(brush, pen, rect);
+    }
+
+    public void DrawGlyphRun(IBrush foreground, GlyphRun glyphRun)
+    {
+        _impl.DrawGlyphRun(foreground, glyphRun);
+    }
+
+    public IDrawingContextLayerImpl CreateLayer(Size size)
+    {
+        return _impl.CreateLayer(size);
+    }
+
+    public void PushClip(Rect clip)
+    {
+        _impl.PushClip(clip);
+    }
+
+    public void PushClip(RoundedRect clip)
+    {
+        _impl.PushClip(clip);
+    }
+
+    public void PopClip()
+    {
+        _impl.PopClip();
+    }
+
+    public void PushOpacity(double opacity)
+    {
+        _impl.PushOpacity(opacity);
+    }
+
+    public void PopOpacity()
+    {
+        _impl.PopOpacity();
+    }
+
+    public void PushOpacityMask(IBrush mask, Rect bounds)
+    {
+        _impl.PushOpacityMask(mask, bounds);
+    }
+
+    public void PopOpacityMask()
+    {
+        _impl.PopOpacityMask();
+    }
+
+    public void PushGeometryClip(IGeometryImpl clip)
+    {
+        _impl.PushGeometryClip(clip);
+    }
+
+    public void PopGeometryClip()
+    {
+        _impl.PopGeometryClip();
+    }
+
+    public void PushBitmapBlendMode(BitmapBlendingMode blendingMode)
+    {
+        _impl.PushBitmapBlendMode(blendingMode);
+    }
+
+    public void PopBitmapBlendMode()
+    {
+        _impl.PopBitmapBlendMode();
+    }
+
+    public void Custom(ICustomDrawOperation custom)
+    {
+        _impl.Custom(custom);
+    }
+
+    public Matrix CutTransform(Matrix4x4 transform) => new Matrix(transform.M11, transform.M12, transform.M21,
+        transform.M22, transform.M41,
+        transform.M42);
+}

src/Avalonia.Base/Rendering/Composition/Server/ReadbackIndices.cs

@@ -0,0 +1,46 @@
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal class ReadbackIndices
+    {
+        private readonly object _lock = new object();
+        public int ReadIndex { get; private set; } = 0;
+        public int WriteIndex { get; private set; } = -1;
+        public ulong ReadRevision { get; private set; }
+        public ulong WriteRevision { get; private set; }
+        private ulong[] _revisions = new ulong[3];
+
+
+        public void NextRead()
+        {
+            lock (_lock)
+            {
+                for (var c = 0; c < 3; c++)
+                {
+                    if (c != WriteIndex && c != ReadIndex && _revisions[c] > ReadRevision)
+                    {
+                        ReadIndex = c;
+                        ReadRevision = _revisions[c];
+                        return;
+                    }
+                }
+            }
+        }
+
+        public void NextWrite(ulong revision)
+        {
+            lock (_lock)
+            {
+                for (var c = 0; c < 3; c++)
+                {
+                    if (c != WriteIndex && c != ReadIndex)
+                    {
+                        WriteIndex = c;
+                        WriteRevision = revision;
+                        _revisions[c] = revision;
+                        return;
+                    }
+                }
+            }
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionBrush.cs

@@ -0,0 +1,7 @@
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal abstract partial class ServerCompositionBrush : ServerObject
+    {
+
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionDrawListVisual.cs

@@ -0,0 +1,41 @@
+using System.Numerics;
+using Avalonia.Collections.Pooled;
+using Avalonia.Platform;
+using Avalonia.Rendering.Composition.Drawing;
+using Avalonia.Rendering.Composition.Transport;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.Utilities;
+
+namespace Avalonia.Rendering.Composition.Server;
+
+internal class ServerCompositionDrawListVisual : ServerCompositionContainerVisual
+{
+    private CompositionDrawList? _renderCommands;
+    
+    public ServerCompositionDrawListVisual(ServerCompositor compositor) : base(compositor)
+    {
+    }
+
+    protected override void ApplyCore(ChangeSet changes)
+    {
+        var ch = (DrawListVisualChanges)changes;
+        if (ch.DrawCommandsIsSet)
+        {
+            _renderCommands?.Dispose();
+            _renderCommands = ch.AcquireDrawCommands();
+        }
+        base.ApplyCore(changes);
+    }
+
+    protected override void RenderCore(CompositorDrawingContextProxy canvas, Matrix4x4 transform)
+    {
+        if (_renderCommands != null)
+        {
+            foreach (var cmd in _renderCommands)
+            {
+                cmd.Item.Render(canvas);
+            }
+        }
+        base.RenderCore(canvas, transform);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionGradientBrush.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal abstract partial class ServerCompositionGradientBrush : ServerCompositionBrush
+    {
+        public ServerCompositionGradientStopCollection Stops { get; }
+        public ServerCompositionGradientBrush(ServerCompositor compositor) : base(compositor)
+        {
+            Stops = new ServerCompositionGradientStopCollection(compositor);
+        }
+
+        public override long LastChangedBy => Math.Max(base.LastChangedBy, (long)Stops.LastChangedBy);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionLinearGradientBrush.cs

@@ -0,0 +1,22 @@
+using Avalonia.Media;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal partial class ServerCompositionLinearGradientBrush 
+    {
+        /*
+        protected override void UpdateBackendBrush(ICbBrush brush)
+        {
+            var stopColors = new Color[Stops.List.Count];
+            var offsets = new float[Stops.List.Count];
+            for (var c = 0; c < Stops.List.Count; c++)
+            {
+                stopColors[c] = Stops.List[c].Color;
+                offsets[c] = Stops.List[c].Offset;
+            }
+
+            ((ICbLinearGradientBrush) brush).Update(StartPoint, EndPoint, stopColors, offsets, ExtendMode);
+        }*/
+
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionSurface.cs

@@ -0,0 +1,9 @@
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal abstract class ServerCompositionSurface : ServerObject
+    {
+        protected ServerCompositionSurface(ServerCompositor compositor) : base(compositor)
+        {
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Numerics;
+using System.Threading;
+using Avalonia.Media;
+using Avalonia.Platform;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal partial class ServerCompositionTarget
+    {
+        private readonly ServerCompositor _compositor;
+        private readonly Func<IRenderTarget> _renderTargetFactory;
+        private static long s_nextId = 1;
+        public long Id { get; }
+        private ulong _frame = 1;
+        private IRenderTarget? _renderTarget;
+
+        public ReadbackIndices Readback { get; } = new();
+
+        public ServerCompositionTarget(ServerCompositor compositor, Func<IRenderTarget> renderTargetFactory) :
+            base(compositor)
+        {
+            _compositor = compositor;
+            _renderTargetFactory = renderTargetFactory;
+            Id = Interlocked.Increment(ref s_nextId);
+        }
+
+        partial void OnIsEnabledChanged()
+        {
+            if (IsEnabled)
+                _compositor.AddCompositionTarget(this);
+            else
+                _compositor.RemoveCompositionTarget(this);
+        }
+
+        public void Render()
+        {
+            if (Root == null) 
+                return;
+            _renderTarget ??= _renderTargetFactory();
+
+            Compositor.UpdateServerTime();
+            using (var context = _renderTarget.CreateDrawingContext(null))
+            {
+                context.Clear(Colors.Transparent);
+                Root.Render(new CompositorDrawingContextProxy(context), Root.CombinedTransformMatrix);
+            }
+
+            Readback.NextWrite(_frame);
+            _frame++;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositor.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal class ServerCompositor : IRenderLoopTask
+    {
+        private readonly IRenderLoop _renderLoop;
+        private readonly Queue<Batch> _batches = new Queue<Batch>(); 
+        public long LastBatchId { get; private set; }
+        public Stopwatch Clock { get; } = Stopwatch.StartNew();
+        public TimeSpan ServerNow { get; private set; }
+        private List<ServerCompositionTarget> _activeTargets = new();
+
+        public ServerCompositor(IRenderLoop renderLoop)
+        {
+            _renderLoop = renderLoop;
+            _renderLoop.Add(this);
+        }
+
+        public void EnqueueBatch(Batch batch)
+        {
+            lock (_batches) 
+                _batches.Enqueue(batch);
+        }
+
+        internal void UpdateServerTime() => ServerNow = Clock.Elapsed;
+
+        List<Batch> _reusableToCompleteList = new();
+        void ApplyPendingBatches()
+        {
+            while (true)
+            {
+                Batch batch;
+                lock (_batches)
+                {
+                    if(_batches.Count == 0)
+                        break;
+                    batch = _batches.Dequeue();
+                }
+
+                foreach (var change in batch.Changes)
+                {
+                    if (change.Dispose)
+                    {
+                        //TODO
+                    }
+                    change.Target!.Apply(change);
+                    change.Reset();
+                }
+
+                _reusableToCompleteList.Add(batch);
+                LastBatchId = batch.SequenceId;
+            }
+        }
+
+        void CompletePendingBatches()
+        {
+            foreach(var batch in _reusableToCompleteList)
+                batch.Complete();
+            _reusableToCompleteList.Clear();
+        }
+
+        bool IRenderLoopTask.NeedsUpdate => false;
+        void IRenderLoopTask.Update(TimeSpan time)
+        {
+        }
+
+        void IRenderLoopTask.Render()
+        {
+            ApplyPendingBatches();
+            foreach (var t in _activeTargets)
+                t.Render();
+            
+            CompletePendingBatches();
+        }
+
+        public void AddCompositionTarget(ServerCompositionTarget target)
+        {
+            _activeTargets.Add(target);
+        }
+
+        public void RemoveCompositionTarget(ServerCompositionTarget target)
+        {
+            _activeTargets.Remove(target);
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerContainerVisual.cs

@@ -0,0 +1,29 @@
+using System.Numerics;
+using Avalonia.Platform;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal class ServerCompositionContainerVisual : ServerCompositionVisual
+    {
+        public ServerCompositionVisualCollection Children { get; }
+        
+        
+        protected override void RenderCore(CompositorDrawingContextProxy canvas, Matrix4x4 transform)
+        {
+            base.RenderCore(canvas, transform);
+
+            foreach (var ch in Children)
+            {
+                var t = transform;
+
+                t = ch.CombinedTransformMatrix * t;
+                ch.Render(canvas, t);
+            }
+        }
+
+        public ServerCompositionContainerVisual(ServerCompositor compositor) : base(compositor)
+        {
+            Children = new ServerCompositionVisualCollection(compositor);
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerCustomDrawVisual.cs

@@ -0,0 +1,31 @@
+using System.Numerics;
+using Avalonia.Platform;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    class ServerCustomDrawVisual<TData> : ServerCompositionContainerVisual
+    {
+        private readonly ICustomDrawVisualRenderer<TData> _renderer;
+        private TData? _data;
+        public ServerCustomDrawVisual(ServerCompositor compositor, ICustomDrawVisualRenderer<TData> renderer) : base(compositor)
+        {
+            _renderer = renderer;
+        }
+
+        protected override void ApplyCore(ChangeSet changes)
+        {
+            var c = (CustomDrawVisualChanges<TData>) changes;
+            if (c.Data.IsSet)
+                _data = c.Data.Value;
+            
+            base.ApplyCore(changes);
+        }
+
+        protected override void RenderCore(CompositorDrawingContextProxy canvas, Matrix4x4 transform)
+        {
+            _renderer.Render(canvas, _data);
+            base.RenderCore(canvas, transform);
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerList.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    class ServerList<T> : ServerObject where T : ServerObject
+    {
+        public List<T> List { get; } = new List<T>();
+        protected override void ApplyCore(ChangeSet changes)
+        {
+            var c = (ListChangeSet<T>) changes;
+            if (c.HasListChanges)
+            {
+                foreach (var lc in c.ListChanges)
+                {
+                    if(lc.Action == ListChangeAction.Clear)
+                        List.Clear();
+                    if(lc.Action == ListChangeAction.RemoveAt)
+                        List.RemoveAt(lc.Index);
+                    if(lc.Action == ListChangeAction.InsertAt)
+                        List.Insert(lc.Index, lc.Added!);
+                    if (lc.Action == ListChangeAction.ReplaceAt)
+                        List[lc.Index] = lc.Added!;
+                }
+            }
+        }
+        
+        public override long LastChangedBy
+        {
+            get
+            {
+                var seq = base.LastChangedBy;
+                foreach (var i in List)
+                    seq = Math.Max(i.LastChangedBy, seq);
+                return seq;
+            }
+        }
+
+        public List<T>.Enumerator GetEnumerator() => List.GetEnumerator();
+
+        public ServerList(ServerCompositor compositor) : base(compositor)
+        {
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerObject.cs

@@ -0,0 +1,36 @@
+using Avalonia.Rendering.Composition.Expressions;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal abstract class ServerObject : IExpressionObject
+    {
+        public ServerCompositor Compositor { get; }
+
+        public virtual long LastChangedBy => ItselfLastChangedBy;
+        public long ItselfLastChangedBy { get; private set; }
+        
+        public ServerObject(ServerCompositor compositor)
+        {
+            Compositor = compositor;
+        }
+
+        protected virtual void ApplyCore(ChangeSet changes)
+        {
+            
+        }
+
+        public void Apply(ChangeSet changes)
+        {
+            ApplyCore(changes);
+            ItselfLastChangedBy = changes.Batch!.SequenceId;
+        }
+
+        public virtual ExpressionVariant GetPropertyForAnimation(string name)
+        {
+            return default;
+        }
+
+        ExpressionVariant IExpressionObject.GetProperty(string name) => GetPropertyForAnimation(name);
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerSolidColorVisual.cs

@@ -0,0 +1,16 @@
+using System.Numerics;
+using Avalonia.Media.Immutable;
+using Avalonia.Platform;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal partial class ServerCompositionSolidColorVisual
+    {
+        protected override void RenderCore(CompositorDrawingContextProxy canvas, Matrix4x4 transform)
+        {
+            canvas.Transform = canvas.CutTransform(transform);
+            canvas.DrawRectangle(new ImmutableSolidColorBrush(Color), null, new RoundedRect(new Rect(new Size(Size))));
+            base.RenderCore(canvas, transform);
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerSpriteVisual.cs

@@ -0,0 +1,20 @@
+using System.Numerics;
+using Avalonia.Platform;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    internal partial class ServerCompositionSpriteVisual
+    {
+
+        protected override void RenderCore(CompositorDrawingContextProxy canvas, Matrix4x4 transform)
+        {
+            if (Brush != null)
+            {
+                //SetTransform(canvas, transform);
+                //canvas.FillRect((Vector2)Size, (ICbBrush)Brush.Brush!);
+            }
+
+            base.RenderCore(canvas, transform);
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Server/ServerVisual.cs

@@ -0,0 +1,92 @@
+using System.Numerics;
+using Avalonia.Platform;
+using Avalonia.Rendering.Composition.Transport;
+
+namespace Avalonia.Rendering.Composition.Server
+{
+    unsafe partial class ServerCompositionVisual : ServerObject
+    {
+        protected virtual void RenderCore(CompositorDrawingContextProxy canvas, Matrix4x4 transform)
+        {
+            
+        }
+        
+        public void Render(CompositorDrawingContextProxy canvas, Matrix4x4 transform)
+        {
+            if(Visible == false)
+                return;
+            if(Opacity == 0)
+                return;
+            canvas.PreTransform = canvas.CutTransform(transform);
+            canvas.Transform = Matrix.Identity;
+            if (Opacity != 1)
+                canvas.PushOpacity(Opacity);
+            if(ClipToBounds)
+                canvas.PushClip(new Rect(new Size(Size.X, Size.Y)));
+            if (Clip != null) 
+                canvas.PushGeometryClip(Clip);
+
+            RenderCore(canvas, transform);
+            
+            if (Clip != null)
+                canvas.PopGeometryClip();
+            if (ClipToBounds)
+                canvas.PopClip();
+            if(Opacity != 1)
+                canvas.PopOpacity();
+        }
+        
+        private ReadbackData _readback0, _readback1, _readback2;
+
+
+        public ref ReadbackData GetReadback(int idx)
+        {
+            if (idx == 0)
+                return ref _readback0;
+            if (idx == 1)
+                return ref _readback1;
+            return ref _readback2;
+        }
+        
+        public Matrix4x4 CombinedTransformMatrix
+        {
+            get
+            {
+                if (Root == null)
+                    return default;
+                
+                var res = MatrixUtils.ComputeTransform(Size, AnchorPoint, CenterPoint, TransformMatrix,
+                    Scale, RotationAngle, Orientation, Offset);
+                var i = Root.Readback;
+                ref var readback = ref GetReadback(i.WriteIndex);
+                readback.Revision = i.WriteRevision;
+                readback.Matrix = res;
+                readback.TargetId = Root.Id;
+
+                return res;
+            }
+        }
+        
+        public struct ReadbackData
+        {
+            public Matrix4x4 Matrix;
+            public bool Visible;
+            public ulong Revision;
+            public long TargetId;
+        }
+
+        partial void ApplyChangesExtra(CompositionVisualChanges c)
+        {
+            if (c.Parent.IsSet)
+                Parent = c.Parent.Value;
+            if (c.Root.IsSet)
+                Root = c.Root.Value;
+        }
+
+        public ServerCompositionTarget? Root { get; private set; }
+
+        public ServerCompositionVisual? Parent { get; private set; }
+    }
+
+
+}

src/Avalonia.Base/Rendering/Composition/Transport/Batch.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    internal class Batch
+    {
+        private static long _nextSequenceId = 1;
+        private static ConcurrentBag<List<ChangeSet>> _pool = new ConcurrentBag<List<ChangeSet>>();
+        public long SequenceId { get; }
+        
+        public Batch()
+        {
+            SequenceId = Interlocked.Increment(ref _nextSequenceId);
+            if (!_pool.TryTake(out var lst))
+                lst = new List<ChangeSet>();
+            Changes = lst;
+        }
+        private TaskCompletionSource<int> _tcs = new TaskCompletionSource<int>();
+        public List<ChangeSet> Changes { get; private set; }
+        public TimeSpan CommitedAt { get; set; }
+        
+        public void Complete()
+        {
+            Changes.Clear();
+            _pool.Add(Changes);
+            Changes = null!;
+
+            _tcs.TrySetResult(0);
+        }
+
+        public Task Completed => _tcs.Task;
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/Change.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Avalonia.Rendering.Composition.Animations;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    struct Change<T>
+    {
+        private T? _value;
+
+        public bool IsSet { get; private set; }
+
+        public T? Value
+        {
+            get
+            {
+                if(!IsSet)
+                    throw new InvalidOperationException();
+                return _value;
+            }
+            set
+            {
+                IsSet = true;
+                _value = value;
+            }
+        }
+
+        public void Reset()
+        {
+            _value = default;
+            IsSet = false;
+        }
+    }
+
+    struct AnimatedChange<T>
+    {
+        private T? _value;
+        private IAnimationInstance? _animation;
+
+        public bool IsValue { get; private set; }
+        public bool IsAnimation { get; private set; }
+
+        public T Value
+        {
+            get
+            {
+                if(!IsValue)
+                    throw new InvalidOperationException();
+                return _value!;
+            }
+            set
+            {
+                IsAnimation = false;
+                _animation = null;
+                IsValue = true;
+                _value = value;
+            }
+        }
+        
+        public IAnimationInstance Animation
+        {
+            get
+            {
+                if(!IsAnimation)
+                    throw new InvalidOperationException();
+                return _animation!;
+            }
+            set
+            {
+                IsValue = false;
+                _value = default;
+                IsAnimation = true;
+                _animation = value;
+            }
+        }
+
+        public void Reset()
+        {
+            this = default;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/ChangeSet.cs

@@ -0,0 +1,36 @@
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    internal abstract class ChangeSet
+    {
+        private readonly IChangeSetPool _pool;
+        public Batch Batch = null!;
+        public ServerObject? Target;
+        public bool Dispose;
+
+        public ChangeSet(IChangeSetPool pool)
+        {
+            _pool = pool;
+        }
+
+        public virtual void Reset()
+        {
+            Batch = null!;
+            Target = null;
+            Dispose = false;
+        }
+
+        public void Return()
+        {
+            _pool.Return(this);
+        }
+    }
+
+    internal class CompositionObjectChanges : ChangeSet
+    {
+        public CompositionObjectChanges(IChangeSetPool pool) : base(pool)
+        {
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/ChangeSetPool.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Concurrent;
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    interface IChangeSetPool
+    {
+        void Return(ChangeSet changes);
+        ChangeSet Get(ServerObject target, Batch batch);
+    }
+    
+    class ChangeSetPool<T> : IChangeSetPool where T : ChangeSet
+    {
+        private readonly Func<IChangeSetPool, T> _factory;
+        private readonly ConcurrentBag<T> _pool = new ConcurrentBag<T>();
+
+        public ChangeSetPool(Func<IChangeSetPool, T> factory)
+        {
+            _factory = factory;
+        }
+
+        public void Return(T changes)
+        {
+            changes.Reset();
+            _pool.Add(changes);
+        }
+
+        void IChangeSetPool.Return(ChangeSet changes) => Return((T) changes);
+        ChangeSet IChangeSetPool.Get(ServerObject target, Batch batch) => Get(target, batch);
+        
+        public T Get(ServerObject target, Batch batch)
+        {
+            if (!_pool.TryTake(out var res))
+                res = _factory(this);
+            res.Target = target;
+            res.Batch = batch;
+            res.Dispose = false;
+            return res;
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/CustomDrawVisualChanges.cs

@@ -0,0 +1,20 @@
+namespace Avalonia.Rendering.Composition.Transport
+{
+    class CustomDrawVisualChanges<TData> : CompositionVisualChanges
+    {
+        public CustomDrawVisualChanges(IChangeSetPool pool) : base(pool)
+        {
+        }
+
+        public Change<TData> Data;
+
+        public override void Reset()
+        {
+            Data.Reset();
+            base.Reset();
+        }
+
+        public new static ChangeSetPool<CustomDrawVisualChanges<TData>> Pool { get; } =
+            new ChangeSetPool<CustomDrawVisualChanges<TData>>(pool => new CustomDrawVisualChanges<TData>(pool));
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/DrawListVisualChanges.cs

@@ -0,0 +1,48 @@
+using System.Collections.Generic;
+using Avalonia.Collections.Pooled;
+using Avalonia.Rendering.Composition.Drawing;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.Utilities;
+
+namespace Avalonia.Rendering.Composition.Transport;
+
+internal class DrawListVisualChanges : CompositionVisualChanges
+{
+    private CompositionDrawList? _drawCommands;
+
+    public DrawListVisualChanges(IChangeSetPool pool) : base(pool)
+    {
+    }
+
+    public CompositionDrawList? DrawCommands
+    {
+        get => _drawCommands;
+        set
+        {
+            _drawCommands?.Dispose();
+            _drawCommands = value;
+            DrawCommandsIsSet = true;
+        }
+    }
+    
+    public bool DrawCommandsIsSet { get; private set; }
+
+    public CompositionDrawList? AcquireDrawCommands()
+    {
+        var rv = _drawCommands;
+        _drawCommands = null;
+        DrawCommandsIsSet = false;
+        return rv;
+    }
+
+    public override void Reset()
+    {
+        _drawCommands?.Dispose();
+        _drawCommands = null;
+        DrawCommandsIsSet = false;
+        base.Reset();
+    }
+
+    public new static ChangeSetPool<DrawListVisualChanges> Pool { get; } =
+        new ChangeSetPool<DrawListVisualChanges>(pool => new(pool));
+}

src/Avalonia.Base/Rendering/Composition/Transport/ListChange.cs

@@ -0,0 +1,19 @@
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    internal class ListChange<T> where T : ServerObject
+    {
+        public int Index;
+        public ListChangeAction Action;
+        public T? Added;
+    }
+
+    internal enum ListChangeAction
+    {
+        InsertAt,
+        RemoveAt,
+        Clear,
+        ReplaceAt
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/ListChangeSet.cs

@@ -0,0 +1,25 @@
+using System.Collections.Generic;
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    class ListChangeSet<T> : ChangeSet where T : ServerObject
+    {
+        private List<ListChange<T>>? _listChanges;
+        public List<ListChange<T>> ListChanges => _listChanges ??= new List<ListChange<T>>();
+        public bool HasListChanges => _listChanges != null;
+
+        public override void Reset()
+        {
+            _listChanges?.Clear();
+            base.Reset();
+        }
+
+        public ListChangeSet(IChangeSetPool pool) : base(pool)
+        {
+        }
+
+        public static readonly ChangeSetPool<ListChangeSet<T>> Pool =
+            new ChangeSetPool<ListChangeSet<T>>(pool => new ListChangeSet<T>(pool));
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/ServerListProxyHelper.cs

@@ -0,0 +1,92 @@
+using System.Collections;
+using System.Collections.Generic;
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    class ServerListProxyHelper<TClient, TServer> : IList<TClient>
+        where TServer : ServerObject
+        where TClient : CompositionObject
+    {
+        private readonly IGetChanges _parent;
+        private readonly List<TClient> _list = new List<TClient>();
+
+        public interface IGetChanges
+        {
+            ListChangeSet<TServer> GetChanges();
+        }
+
+        public ServerListProxyHelper(IGetChanges parent)
+        {
+            _parent = parent;
+        }
+
+        IEnumerator<TClient> IEnumerable<TClient>.GetEnumerator() => GetEnumerator();
+        public List<TClient>.Enumerator GetEnumerator() => _list.GetEnumerator();
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+        public void Add(TClient item) => Insert(_list.Count, item);
+
+        public void Clear()
+        {
+            _list.Clear();
+            _parent.GetChanges().ListChanges.Add(new ListChange<TServer>
+            {
+                Action = ListChangeAction.Clear
+            });
+        }
+
+        public bool Contains(TClient item) => _list.Contains(item);
+
+        public void CopyTo(TClient[] array, int arrayIndex) => _list.CopyTo(array, arrayIndex);
+
+        public bool Remove(TClient item)
+        {
+            var idx = _list.IndexOf(item);
+            if (idx == -1)
+                return false;
+            RemoveAt(idx);
+            return true;
+        }
+
+        public int Count => _list.Count;
+        public bool IsReadOnly => false;
+        public int IndexOf(TClient item) => _list.IndexOf(item);
+
+        public void Insert(int index, TClient item)
+        {
+            _list.Insert(index, item);
+            _parent.GetChanges().ListChanges.Add(new ListChange<TServer>
+            {
+                Action = ListChangeAction.InsertAt,
+                Index = index,
+                Added = (TServer) item.Server
+            });
+        }
+
+        public void RemoveAt(int index)
+        {
+            _list.RemoveAt(index);
+            _parent.GetChanges().ListChanges.Add(new ListChange<TServer>
+            {
+                Action = ListChangeAction.RemoveAt,
+                Index = index
+            });
+        }
+
+        public TClient this[int index]
+        {
+            get => _list[index];
+            set
+            {
+                _list[index] = value;
+                _parent.GetChanges().ListChanges.Add(new ListChange<TServer>
+                {
+                    Action = ListChangeAction.ReplaceAt,
+                    Index = index,
+                    Added = (TServer) value.Server
+                });
+            }
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Transport/VisualChanges.cs

@@ -0,0 +1,16 @@
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition.Transport
+{
+    partial class CompositionVisualChanges
+    {
+        public Change<ServerCompositionVisual> Parent;
+        public Change<ServerCompositionTarget> Root;
+
+        partial void ResetExtra()
+        {
+            Parent.Reset();
+            Root.Reset();
+        }
+    }
+}

src/Avalonia.Base/Rendering/Composition/Utils/CubicBezier.cs

@@ -0,0 +1,302 @@
+// ReSharper disable InconsistentNaming
+// Ported from Chromium project https://github.com/chromium/chromium/blob/374d31b7704475fa59f7b2cb836b3b68afdc3d79/ui/gfx/geometry/cubic_bezier.cc
+
+using System;
+
+// ReSharper disable CompareOfFloatsByEqualityOperator
+// ReSharper disable CommentTypo
+// ReSharper disable MemberCanBePrivate.Global
+// ReSharper disable TooWideLocalVariableScope
+// ReSharper disable UnusedMember.Global
+#pragma warning disable 649
+
+namespace Avalonia.Rendering.Composition.Utils
+{
+    internal unsafe struct CubicBezier
+    {
+        const int CUBIC_BEZIER_SPLINE_SAMPLES = 11;
+        double ax_;
+        double bx_;
+        double cx_;
+
+        double ay_;
+        double by_;
+        double cy_;
+
+        double start_gradient_;
+        double end_gradient_;
+
+        double range_min_;
+        double range_max_;
+        private bool monotonically_increasing_;
+
+        fixed double spline_samples_[CUBIC_BEZIER_SPLINE_SAMPLES];
+
+        public CubicBezier(double p1x, double p1y, double p2x, double p2y) : this()
+        {
+            InitCoefficients(p1x, p1y, p2x, p2y);
+            InitGradients(p1x, p1y, p2x, p2y);
+            InitRange(p1y, p2y);
+            InitSpline();
+        }
+
+        public readonly double SampleCurveX(double t)
+        {
+            // `ax t^3 + bx t^2 + cx t' expanded using Horner's rule.
+            return ((ax_ * t + bx_) * t + cx_) * t;
+        }
+
+        readonly double SampleCurveY(double t)
+        {
+            return ((ay_ * t + by_) * t + cy_) * t;
+        }
+
+        readonly double SampleCurveDerivativeX(double t)
+        {
+            return (3.0 * ax_ * t + 2.0 * bx_) * t + cx_;
+        }
+
+        readonly double SampleCurveDerivativeY(double t)
+        {
+            return (3.0 * ay_ * t + 2.0 * by_) * t + cy_;
+        }
+
+        public readonly double SolveWithEpsilon(double x, double epsilon)
+        {
+            if (x < 0.0)
+                return 0.0 + start_gradient_ * x;
+            if (x > 1.0)
+                return 1.0 + end_gradient_ * (x - 1.0);
+            return SampleCurveY(SolveCurveX(x, epsilon));
+        }
+        
+        void InitCoefficients(double p1x,
+            double p1y,
+            double p2x,
+            double p2y)
+        {
+            // Calculate the polynomial coefficients, implicit first and last control
+            // points are (0,0) and (1,1).
+            cx_ = 3.0 * p1x;
+            bx_ = 3.0 * (p2x - p1x) - cx_;
+            ax_ = 1.0 - cx_ - bx_;
+
+            cy_ = 3.0 * p1y;
+            by_ = 3.0 * (p2y - p1y) - cy_;
+            ay_ = 1.0 - cy_ - by_;
+
+#if DEBUG
+            // Bezier curves with x-coordinates outside the range [0,1] for internal
+            // control points may have multiple values for t for a given value of x.
+            // In this case, calls to SolveCurveX may produce ambiguous results.
+            monotonically_increasing_ = p1x >= 0 && p1x <= 1 && p2x >= 0 && p2x <= 1;
+#endif
+        }
+
+        void InitGradients(double p1x,
+            double p1y,
+            double p2x,
+            double p2y)
+        {
+            // End-point gradients are used to calculate timing function results
+            // outside the range [0, 1].
+            //
+            // There are four possibilities for the gradient at each end:
+            // (1) the closest control point is not horizontally coincident with regard to
+            //     (0, 0) or (1, 1). In this case the line between the end point and
+            //     the control point is tangent to the bezier at the end point.
+            // (2) the closest control point is coincident with the end point. In
+            //     this case the line between the end point and the far control
+            //     point is tangent to the bezier at the end point.
+            // (3) both internal control points are coincident with an endpoint. There
+            //     are two special case that fall into this category:
+            //     CubicBezier(0, 0, 0, 0) and CubicBezier(1, 1, 1, 1). Both are
+            //     equivalent to linear.
+            // (4) the closest control point is horizontally coincident with the end
+            //     point, but vertically distinct. In this case the gradient at the
+            //     end point is Infinite. However, this causes issues when
+            //     interpolating. As a result, we break down to a simple case of
+            //     0 gradient under these conditions.
+
+            if (p1x > 0)
+                start_gradient_ = p1y / p1x;
+            else if (p1y == 0 && p2x > 0)
+                start_gradient_ = p2y / p2x;
+            else if (p1y == 0 && p2y == 0)
+                start_gradient_ = 1;
+            else
+                start_gradient_ = 0;
+
+            if (p2x < 1)
+                end_gradient_ = (p2y - 1) / (p2x - 1);
+            else if (p2y == 1 && p1x < 1)
+                end_gradient_ = (p1y - 1) / (p1x - 1);
+            else if (p2y == 1 && p1y == 1)
+                end_gradient_ = 1;
+            else
+                end_gradient_ = 0;
+        }
+
+        const double kBezierEpsilon = 1e-7;
+
+        void InitRange(double p1y, double p2y)
+        {
+            range_min_ = 0;
+            range_max_ = 1;
+            if (0 <= p1y && p1y < 1 && 0 <= p2y && p2y <= 1)
+                return;
+
+            double epsilon = kBezierEpsilon;
+
+            // Represent the function's derivative in the form at^2 + bt + c
+            // as in sampleCurveDerivativeY.
+            // (Technically this is (dy/dt)*(1/3), which is suitable for finding zeros
+            // but does not actually give the slope of the curve.)
+            double a = 3.0 * ay_;
+            double b = 2.0 * by_;
+            double c = cy_;
+
+            // Check if the derivative is constant.
+            if (Math.Abs(a) < epsilon && Math.Abs(b) < epsilon)
+                return;
+
+            // Zeros of the function's derivative.
+            double t1;
+            double t2 = 0;
+
+            if (Math.Abs(a) < epsilon)
+            {
+                // The function's derivative is linear.
+                t1 = -c / b;
+            }
+            else
+            {
+                // The function's derivative is a quadratic. We find the zeros of this
+                // quadratic using the quadratic formula.
+                double discriminant = b * b - 4 * a * c;
+                if (discriminant < 0)
+                    return;
+                double discriminant_sqrt = Math.Sqrt(discriminant);
+                t1 = (-b + discriminant_sqrt) / (2 * a);
+                t2 = (-b - discriminant_sqrt) / (2 * a);
+            }
+
+            double sol1 = 0;
+            double sol2 = 0;
+
+            // If the solution is in the range [0,1] then we include it, otherwise we
+            // ignore it.
+
+            // An interesting fact about these beziers is that they are only
+            // actually evaluated in [0,1]. After that we take the tangent at that point
+            // and linearly project it out.
+            if (0 < t1 && t1 < 1)
+                sol1 = SampleCurveY(t1);
+
+            if (0 < t2 && t2 < 1)
+                sol2 = SampleCurveY(t2);
+
+            range_min_ = Math.Min(Math.Min(range_min_, sol1), sol2);
+            range_max_ = Math.Max(Math.Max(range_max_, sol1), sol2);
+        }
+
+        void InitSpline()
+        {
+            double delta_t = 1.0 / (CUBIC_BEZIER_SPLINE_SAMPLES - 1);
+            for (int i = 0; i < CUBIC_BEZIER_SPLINE_SAMPLES; i++)
+            {
+                spline_samples_[i] = SampleCurveX(i * delta_t);
+            }
+        }
+
+        const int kMaxNewtonIterations = 4;
+
+
+        public readonly double SolveCurveX(double x, double epsilon)
+        {
+            if (x < 0 || x > 1)
+                throw new ArgumentException();
+
+            double t0 = 0;
+            double t1 = 0;
+            double t2 = x;
+            double x2 = 0;
+            double d2;
+            int i;
+
+#if DEBUG
+            if (!monotonically_increasing_)
+                throw new InvalidOperationException();
+#endif
+
+            // Linear interpolation of spline curve for initial guess.
+            double delta_t = 1.0 / (CUBIC_BEZIER_SPLINE_SAMPLES - 1);
+            for (i = 1; i < CUBIC_BEZIER_SPLINE_SAMPLES; i++)
+            {
+                if (x <= spline_samples_[i])
+                {
+                    t1 = delta_t * i;
+                    t0 = t1 - delta_t;
+                    t2 = t0 + (t1 - t0) * (x - spline_samples_[i - 1]) /
+                        (spline_samples_[i] - spline_samples_[i - 1]);
+                    break;
+                }
+            }
+
+            // Perform a few iterations of Newton's method -- normally very fast.
+            // See https://en.wikipedia.org/wiki/Newton%27s_method.
+            double newton_epsilon = Math.Min(kBezierEpsilon, epsilon);
+            for (i = 0; i < kMaxNewtonIterations; i++)
+            {
+                x2 = SampleCurveX(t2) - x;
+                if (Math.Abs(x2) < newton_epsilon)
+                    return t2;
+                d2 = SampleCurveDerivativeX(t2);
+                if (Math.Abs(d2) < kBezierEpsilon)
+                    break;
+                t2 = t2 - x2 / d2;
+            }
+
+            if (Math.Abs(x2) < epsilon)
+                return t2;
+
+            // Fall back to the bisection method for reliability.
+            while (t0 < t1)
+            {
+                x2 = SampleCurveX(t2);
+                if (Math.Abs(x2 - x) < epsilon)
+                    return t2;
+                if (x > x2)
+                    t0 = t2;
+                else
+                    t1 = t2;
+                t2 = (t1 + t0) * .5;
+            }
+
+            // Failure.
+            return t2;
+        }
+
+        public readonly double Solve(double x)
+        {
+            return SolveWithEpsilon(x, kBezierEpsilon);
+        }
+
+        public readonly double SlopeWithEpsilon(double x, double epsilon)
+        {
+            x = MathExt.Clamp(x, 0.0, 1.0);
+            double t = SolveCurveX(x, epsilon);
+            double dx = SampleCurveDerivativeX(t);
+            double dy = SampleCurveDerivativeY(t);
+            return dy / dx;
+        }
+
+        public readonly double Slope(double x)
+        {
+            return SlopeWithEpsilon(x, kBezierEpsilon);
+        }
+
+        public readonly double RangeMin => range_min_;
+        public readonly double RangeMax => range_max_;
+    }
+}

src/Avalonia.Base/Rendering/Composition/Utils/MathExt.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace Avalonia.Rendering.Composition.Utils
+{
+    static class MathExt
+    {
+        public static float Clamp(float value, float min, float max)
+        {
+            var amax = Math.Max(min, max);
+            var amin = Math.Min(min, max);
+            return Math.Min(Math.Max(value, amin), amax);
+        }
+        
+        public static double Clamp(double value, double min, double max)
+        {
+            var amax = Math.Max(min, max);
+            var amin = Math.Min(min, max);
+            return Math.Min(Math.Max(value, amin), amax);
+        }
+
+
+    }
+}

src/Avalonia.Base/Rendering/Composition/Visual.cs

@@ -0,0 +1,64 @@
+using System.Numerics;
+
+namespace Avalonia.Rendering.Composition
+{
+    public abstract partial class CompositionVisual
+    {
+        private CompositionVisual? _parent;
+        private CompositionTarget? _root;
+
+        public CompositionVisual? Parent
+        {
+            get => _parent;
+            internal set
+            {
+                if (_parent == value)
+                    return;
+                _parent = value;
+                Changes.Parent.Value = value?.Server;
+                Root = _parent?.Root;
+            }
+        }
+        
+        // TODO: hide behind private-ish API
+        public CompositionTarget? Root
+        {
+            get => _root;
+            internal set
+            {
+                var changed = _root != value;
+                _root = value;
+                Changes.Root.Value = value?.Server;
+                if (changed)
+                    OnRootChanged();
+            }
+        }
+
+        private protected virtual void OnRootChanged()
+        {
+        }
+
+
+        internal Matrix4x4? TryGetServerTransform()
+        {
+            if (Root == null)
+                return null;
+            var i = Root.Server.Readback;
+            ref var readback = ref Server.GetReadback(i.ReadIndex);
+            
+            // CompositionVisual wasn't visible
+            if (readback.Revision < i.ReadRevision)
+                return null;
+            
+            // CompositionVisual was reparented (potential race here)
+            if (readback.TargetId != Root.Server.Id)
+                return null;
+            
+            return readback.Matrix;
+        }
+        
+        internal object? Tag { get; set; }
+
+        internal virtual bool HitTest(Vector2 point) => true;
+    }
+}

src/Avalonia.Base/Rendering/Composition/VisualCollection.cs

@@ -0,0 +1,64 @@
+using System;
+using Avalonia.Rendering.Composition.Server;
+
+namespace Avalonia.Rendering.Composition
+{
+    public partial class CompositionVisualCollection : CompositionObject
+    {
+        private CompositionVisual _owner;
+        internal CompositionVisualCollection(CompositionVisual parent, ServerCompositionVisualCollection server) : base(parent.Compositor, server)
+        {
+            _owner = parent;
+            InitializeDefaults();
+        }
+        
+        public void InsertAbove(CompositionVisual newChild, CompositionVisual sibling)
+        {
+            var idx = _list.IndexOf(sibling);
+            if (idx == -1)
+                throw new InvalidOperationException();
+            
+            Insert(idx + 1, newChild);
+        }
+        
+        public void InsertBelow(CompositionVisual newChild, CompositionVisual sibling)
+        {
+            var idx = _list.IndexOf(sibling);
+            if (idx == -1)
+                throw new InvalidOperationException();
+            Insert(idx, newChild);
+        }
+
+        public void InsertAtTop(CompositionVisual newChild) => Insert(_list.Count, newChild);
+
+        public void InsertAtBottom(CompositionVisual newChild) => Insert(0, newChild);
+
+        public void RemoveAll() => Clear();
+
+        partial void OnAdded(CompositionVisual item) => item.Parent = _owner;
+
+        partial void OnBeforeReplace(CompositionVisual oldItem, CompositionVisual newItem)
+        {
+            if (oldItem != newItem)
+                OnBeforeAdded(newItem);
+        }
+
+        partial void OnReplace(CompositionVisual oldItem, CompositionVisual newItem)
+        {
+            if (oldItem != newItem)
+            {
+                OnRemoved(oldItem);
+                OnAdded(newItem);
+            }
+        }
+
+        partial void OnRemoved(CompositionVisual item) => item.Parent = null;
+
+
+        partial void OnBeforeAdded(CompositionVisual item)
+        {
+            if (item.Parent != null)
+                throw new InvalidOperationException("Visual already has a parent");
+        }
+    }
+}

src/Avalonia.Base/Rendering/IRenderer.cs

@@ -1,6 +1,7 @@
 using System;
 using Avalonia.VisualTree;
 using System.Collections.Generic;
+using Avalonia.Rendering.Composition;
 
 namespace Avalonia.Rendering
 {
@@ -87,4 +88,9 @@ namespace Avalonia.Rendering
         /// </summary>
         void Stop();
     }
+    
+    public interface IRendererWithCompositor : IRenderer
+    {
+        Compositor Compositor { get; }
+    }
 }

src/Avalonia.Base/Rendering/SceneGraph/DeferredDrawingContextImpl.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Numerics;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Utilities;

src/Avalonia.Base/Size.cs

@@ -52,6 +52,17 @@ namespace Avalonia
             _width = width;
             _height = height;
         }
+        
+#if !BUILDTASK
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Size"/> structure.
+        /// </summary>
+        /// <param name="vector2">The vector to take values from.</param>
+        public Size(System.Numerics.Vector2 vector2) : this(vector2.X, vector2.Y)
+        {
+            
+        }
+#endif
 
         /// <summary>
         /// Gets the aspect ratio of the size.

src/Avalonia.Base/Threading/DispatcherPriority.cs

@@ -62,10 +62,20 @@ namespace Avalonia.Threading
         /// </summary>
         public static readonly DispatcherPriority Render = new(5);
 
+        /// <summary>
+        /// The job will be processed with the same priority as composition batch commit.
+        /// </summary>
+        public static readonly DispatcherPriority CompositionBatch = new(6);
+        
+        /// <summary>
+        /// The job will be processed with the same priority as composition updates.
+        /// </summary>
+        public static readonly DispatcherPriority Composition = new(7);
+        
         /// <summary>
         /// The job will be processed with the same priority as render.
         /// </summary>
-        public static readonly DispatcherPriority Layout = new(6);
+        public static readonly DispatcherPriority Layout = new(8);
 
         /// <summary>
         /// The job will be processed with the same priority as data binding.
@@ -75,7 +85,7 @@ namespace Avalonia.Threading
         /// <summary>
         /// The job will be processed before other asynchronous operations.
         /// </summary>
-        public static readonly DispatcherPriority Send = new(7);
+        public static readonly DispatcherPriority Send = new(9);
 
         /// <summary>
         /// Maximum possible priority

src/Avalonia.Base/Visual.cs

@@ -1,3 +1,7 @@
+
+
+#nullable enable
+
 using System;
 using System.Collections;
 using System.Collections.Specialized;
@@ -8,11 +12,10 @@ using Avalonia.LogicalTree;
 using Avalonia.Media;
 using Avalonia.Metadata;
 using Avalonia.Rendering;
+using Avalonia.Rendering.Composition;
+using Avalonia.Rendering.Composition.Server;
 using Avalonia.Utilities;
 using Avalonia.VisualTree;
-
-#nullable enable
-
 namespace Avalonia
 {
     /// <summary>
@@ -288,6 +291,8 @@ namespace Avalonia
         /// </summary>
         protected IRenderRoot? VisualRoot => _visualRoot ?? (this as IRenderRoot);
 
+        internal CompositionDrawListVisual? CompositionVisual { get; private set; }
+        
         /// <summary>
         /// Gets a value indicating whether this control is attached to a visual root.
         /// </summary>
@@ -432,6 +437,10 @@ namespace Avalonia
             }
 
             EnableTransitions();
+            if (_visualRoot.Renderer is IRendererWithCompositor compositingRenderer)
+            {
+                AttachToCompositor(compositingRenderer.Compositor);
+            }
             OnAttachedToVisualTree(e);
             AttachedToVisualTree?.Invoke(this, e);
             InvalidateVisual();
@@ -452,6 +461,14 @@ namespace Avalonia
             }
         }
 
+        internal CompositionVisual AttachToCompositor(Compositor compositor)
+        {
+            if (CompositionVisual == null || CompositionVisual.Compositor != compositor)
+                CompositionVisual = new CompositionDrawListVisual(compositor,
+                    new ServerCompositionDrawListVisual(compositor.Server), this);
+            return CompositionVisual;
+        }
+
         /// <summary>
         /// Calls the <see cref="OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs)"/> method 
         /// for this control and all of its visual descendants.
@@ -564,7 +581,7 @@ namespace Avalonia
                 {
                     newValue.Changed += sender.RenderTransformChanged;
                 }
-
+                
                 sender.InvalidateVisual();
             }
         }

src/Avalonia.Base/composition-schema.xml

@@ -0,0 +1,70 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<NComposition>
+    <Using>System.Numerics</Using>
+    <Using>Avalonia.Rendering.Composition.Server</Using>
+    <Using>Avalonia.Rendering.Composition.Transport</Using>
+    <Using>Avalonia.Rendering.Composition.Animations</Using>
+
+    <Manual Name="CompositionContainerVisual" />
+    <Manual Name="ICompositionSurface" ServerName="ServerCompositionSurface" />
+    <Object Name="CompositionVisual" Abstract="true">
+        <Property Name="Visible" Type="bool" Animated="true" DefaultValue="true"/>
+        <Property Name="Opacity" Type="float" Animated="true" DefaultValue="1"/>
+        <Property Name="Clip" Type="Avalonia.Platform.IGeometryImpl?" />
+        <Property Name="ClipToBounds" Type="bool" Animated="true" DefaultValue="true"/>
+        <Property Name="Offset" Type="Vector3" Animated="true"/>
+        <Property Name="Size" Type="Vector2" Animated="true"/>
+        <Property Name="AnchorPoint" Type="Vector2" Animated="true"/>
+        <Property Name="CenterPoint" Type="Vector3" Animated="true"/>
+        <Property Name="RotationAngle" Type="float" Animated="true"/>
+        <Property Name="Orientation" Type="Quaternion" DefaultValue="Quaternion.Identity" Animated="true"/>
+        <Property Name="Scale" Type="Vector3" DefaultValue="new Vector3(1, 1, 1)" Animated="true"/>
+        <Property Name="TransformMatrix" Type="Matrix4x4" DefaultValue="Matrix4x4.Identity" Animated="true"/>
+    </Object>
+    <List Name="CompositionVisualCollection" ItemType="CompositionVisual" CustomCtor="true"/>
+    <Object Name="CompositionTarget" CustomServerCtor="true">
+        <Property Name="Root" Type="CompositionVisual?"/>
+        <Property Name="IsEnabled" Type="bool"/>
+    </Object>
+    
+    <Object Name="CompositionSolidColorVisual" Inherits="CompositionContainerVisual" ChangesBase="CompositionVisual">
+        <Property Name="Color" Type="Avalonia.Media.Color" Animated="true"/>
+    </Object>
+    
+    <Object Name="CompositionSpriteVisual" Inherits="CompositionContainerVisual" ChangesBase="CompositionVisual">
+        <Property Name="Brush" Type="CompositionBrush?"/>
+    </Object>
+    
+    <Object Name="CompositionBrush" Abstract="true">
+        
+    </Object>
+        
+    <Object Name="CompositionColorGradientStop">
+        <Property Name="Color" Type="Avalonia.Media.Color" Animated="true"/>
+        <Property Name="Offset" Type="float" Animated="true"/>
+    </Object>
+    <List Name="CompositionGradientStopCollection" ItemType="CompositionColorGradientStop" />
+    <Brush Name="CompositionGradientBrush" Abstract="true" CustomCtor="true" CustomServerCtor="true">
+        <Property Name="ExtendMode" Type="CompositionGradientExtendMode"/>
+    </Brush>
+    <Brush Name="CompositionLinearGradientBrush" Inherits="CompositionGradientBrush" CustomUpdate="true">
+        <Property Name="StartPoint" Type="Vector2" Animated="true"/>
+        <Property Name="EndPoint" Type="Vector2" Animated="true"/>
+    </Brush>
+    <Brush Name="CompositionColorBrush">
+        <Property Name="Color" Type="Avalonia.Media.Color" Animated="true"/>
+    </Brush>
+    <Brush Name="CompositionSurfaceBrush">
+        <Property Name="Surface" Type="ICompositionSurface?"/>
+        <Property Name="Stretch" Type="CompositionStretch" DefaultValue="CompositionStretch.Fill" />
+        <Property Name="TileMode" Type="CompositionTileMode" />
+    </Brush>
+    
+    <KeyFrameAnimation Name="Scalar" Type="float"/>
+    <KeyFrameAnimation Name="Boolean" Type="bool"/>
+    <KeyFrameAnimation Name="Color" Type="Avalonia.Media.Color"/>
+    <KeyFrameAnimation Type="Vector2"/>
+    <KeyFrameAnimation Type="Vector3"/>
+    <KeyFrameAnimation Type="Vector4"/>
+    <KeyFrameAnimation Type="Quaternion"/>
+</NComposition>

src/Avalonia.Headless/HeadlessPlatformRenderInterface.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Numerics;
 using System.Runtime.InteropServices;
 using Avalonia.Media;
 using Avalonia.Platform;
@@ -344,6 +345,7 @@ namespace Avalonia.Headless
             }
 
             public Matrix Transform { get; set; }
+
             public void Clear(Color color)
             {
 

src/Avalonia.SourceGenerator/CompositionGenerator/CompositionRoslynGenerator.cs

@@ -0,0 +1,21 @@
+using System.IO;
+using System.Xml.Serialization;
+using Microsoft.CodeAnalysis;
+
+namespace Avalonia.SourceGenerator.CompositionGenerator;
+
+[Generator(LanguageNames.CSharp)]
+public class CompositionRoslynGenerator : IIncrementalGenerator
+{
+    public void Initialize(IncrementalGeneratorInitializationContext context)
+    {
+        var schema = context.AdditionalTextsProvider.Where(static file => file.Path.EndsWith("composition-schema.xml"));
+        var configs = schema.Select((t, _) =>
+            (GConfig)new XmlSerializer(typeof(GConfig)).Deserialize(new StringReader(t.GetText().ToString())));
+        context.RegisterSourceOutput(configs, (spc, config) =>
+        {
+            var generator = new Generator(spc, config);
+            generator.Generate();
+        });
+    }
+}

src/Avalonia.SourceGenerator/CompositionGenerator/Config.cs

@@ -0,0 +1,116 @@
+#nullable disable
+using System.Collections.Generic;
+using System.Xml.Serialization;
+
+namespace Avalonia.SourceGenerator.CompositionGenerator
+{
+
+        
+    [XmlRoot("NComposition")]
+    public class GConfig
+    {
+        [XmlElement("Using")]
+        public List<GUsing> Usings { get; set; } = new List<GUsing>();
+        
+        [XmlElement(typeof(GManualClass), ElementName = "Manual")]
+        public List<GManualClass> ManualClasses { get; set; } = new List<GManualClass>();
+        
+        [XmlElement(typeof(GClass), ElementName = "Object")]
+        [XmlElement(typeof(GBrush), ElementName = "Brush")]
+        [XmlElement(typeof(GList), ElementName = "List")]
+        public List<GClass> Classes { get; set; } = new List<GClass>();
+
+        [XmlElement(typeof(GAnimationType), ElementName = "KeyFrameAnimation")]
+        public List<GAnimationType> KeyFrameAnimations { get; set; } = new List<GAnimationType>();
+    }
+        
+    public class GUsing
+    {
+        [XmlText]
+        public string Name { get; set; }
+    }
+
+    public class GManualClass
+    {
+        [XmlAttribute]
+        public string Name { get; set; }
+        
+        [XmlAttribute]
+        public string ServerName { get; set; }
+    }
+    
+    public class GImplements
+    {
+        [XmlAttribute]
+        public string Name { get; set; }
+        [XmlAttribute]
+        public string ServerName { get; set; }
+    }
+    
+    public class GClass
+    {
+        [XmlAttribute]
+        public string Name { get; set; }
+        
+        [XmlAttribute]
+        public string Inherits { get; set; }
+        
+        [XmlAttribute]
+        public string ChangesBase { get; set; }
+        
+        [XmlAttribute]
+        public string ServerBase { get; set; }
+        
+        [XmlAttribute]
+        public bool CustomCtor { get; set; }
+        
+        [XmlAttribute]
+        public bool CustomServerCtor { get; set; }
+        
+        [XmlElement(typeof(GImplements), ElementName = "Implements")]
+        public List<GImplements> Implements { get; set; } = new List<GImplements>();
+        
+        [XmlAttribute]
+        public bool Abstract { get; set; }
+        
+        [XmlElement(typeof(GProperty), ElementName = "Property")]
+        public List<GProperty> Properties { get; set; } = new List<GProperty>();
+    }
+
+    public class GBrush : GClass
+    {
+        [XmlAttribute]
+        public bool CustomUpdate { get; set; }
+        
+        public GBrush()
+        {
+            Inherits = "CompositionBrush";
+        }
+    }
+
+    public class GList : GClass
+    {
+        [XmlAttribute]
+        public string ItemType { get; set; }
+    }
+
+    public class GProperty
+    {
+        [XmlAttribute]
+        public string Name { get; set; }
+        [XmlAttribute]
+        public string Type { get; set; }
+        [XmlAttribute]
+        public string DefaultValue { get; set; }
+        [XmlAttribute]
+        public bool Animated { get; set; }
+    }
+
+    public class GAnimationType
+    {
+        [XmlAttribute]
+        public string Name { get; set; }
+        [XmlAttribute]
+        public string Type { get; set; }
+    }
+}

src/Avalonia.SourceGenerator/CompositionGenerator/Extensions.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Linq;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+namespace Avalonia.SourceGenerator.CompositionGenerator
+{
+    public static class Extensions
+    {
+        public static ClassDeclarationSyntax AddModifiers(this ClassDeclarationSyntax cl, params SyntaxKind[] modifiers)
+        {
+            if (modifiers == null)
+                return cl;
+            return cl.AddModifiers(modifiers.Select(x => SyntaxFactory.Token(x)).ToArray());
+        }
+        
+        public static MethodDeclarationSyntax AddModifiers(this MethodDeclarationSyntax cl, params SyntaxKind[] modifiers)
+        {
+            if (modifiers == null)
+                return cl;
+            return cl.AddModifiers(modifiers.Select(x => SyntaxFactory.Token(x)).ToArray());
+        }
+        
+        public static PropertyDeclarationSyntax AddModifiers(this PropertyDeclarationSyntax cl, params SyntaxKind[] modifiers)
+        {
+            if (modifiers == null)
+                return cl;
+            return cl.AddModifiers(modifiers.Select(x => SyntaxFactory.Token(x)).ToArray());
+        }
+
+        public static ConstructorDeclarationSyntax AddModifiers(this ConstructorDeclarationSyntax cl, params SyntaxKind[] modifiers)
+        {
+            if (modifiers == null)
+                return cl;
+            return cl.AddModifiers(modifiers.Select(x => SyntaxFactory.Token(x)).ToArray());
+        }
+        
+        public static AccessorDeclarationSyntax AddModifiers(this AccessorDeclarationSyntax cl, params SyntaxKind[] modifiers)
+        {
+            if (modifiers == null)
+                return cl;
+            return cl.AddModifiers(modifiers.Select(x => SyntaxFactory.Token(x)).ToArray());
+        }
+
+        public static string WithLowerFirst(this string s)
+        {
+            if (string.IsNullOrEmpty(s))
+                return s;
+            return char.ToLowerInvariant(s[0]) + s.Substring(1);
+        }
+
+        public static ExpressionSyntax MemberAccess(params string[] identifiers)
+        {
+            if (identifiers == null || identifiers.Length == 0)
+                throw new ArgumentException();
+            var expr = (ExpressionSyntax)IdentifierName(identifiers[0]);
+            for (var c = 1; c < identifiers.Length; c++)
+                expr = MemberAccess(expr, identifiers[c]);
+            return expr;
+        }
+        
+        public static ExpressionSyntax MemberAccess(ExpressionSyntax expr, params string[] identifiers)
+        {
+            foreach (var i in identifiers)
+                expr = MemberAccess(expr, i);
+            return expr;
+        }
+        
+        public static MemberAccessExpressionSyntax MemberAccess(ExpressionSyntax expr, string identifier) =>
+            MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, expr, IdentifierName(identifier));
+
+        public static ExpressionSyntax ConditionalMemberAccess(ExpressionSyntax expr, string member, bool checkNull)
+        {
+            if (checkNull)
+                return ConditionalAccessExpression(expr, MemberBindingExpression(IdentifierName(member)));
+            return MemberAccess(expr, member);
+        }
+        
+        public static ClassDeclarationSyntax WithBaseType(this ClassDeclarationSyntax cl, string bt)
+        {
+            return cl.AddBaseListTypes(SimpleBaseType(SyntaxFactory.ParseTypeName(bt)));
+        }
+
+        public static string StripPrefix(this string s, string prefix) => string.IsNullOrEmpty(s)
+            ? s
+            : s.StartsWith(prefix)
+                ? s.Substring(prefix.Length)
+                : s;
+    }
+}

src/Avalonia.SourceGenerator/CompositionGenerator/Generator.KeyFrameAnimation.cs

@@ -0,0 +1,59 @@
+namespace Avalonia.SourceGenerator.CompositionGenerator
+{
+    public partial class Generator
+    {
+        void GenerateAnimations()
+        {
+            var code = $@"using System.Numerics;
+using Avalonia.Rendering.Composition.Animations;
+using Avalonia.Rendering.Composition.Expressions;
+
+namespace Avalonia.Rendering.Composition
+{{
+";
+
+            foreach (var a in _config.KeyFrameAnimations)
+            {
+                var name = a.Name ?? a.Type;
+
+                code += $@"
+    public class {name}KeyFrameAnimation : KeyFrameAnimation
+    {{
+        public {name}KeyFrameAnimation(Compositor compositor) : base(compositor)
+        {{
+        }}
+
+        internal override IAnimationInstance CreateInstance(Avalonia.Rendering.Composition.Server.ServerObject targetObject, ExpressionVariant? finalValue)
+        {{
+            return new KeyFrameAnimationInstance<{a.Type}>({name}Interpolator.Instance, _keyFrames.Snapshot(), CreateSnapshot(true), 
+                finalValue?.CastOrDefault<{a.Type}>(), targetObject,
+                DelayBehavior, DelayTime, Direction, Duration, IterationBehavior,
+                IterationCount, StopBehavior);
+        }}
+        
+        private KeyFrames<{a.Type}> _keyFrames = new KeyFrames<{a.Type}>();
+        private protected override IKeyFrames KeyFrames => _keyFrames;
+
+        public void InsertKeyFrame(float normalizedProgressKey, {a.Type} value, CompositionEasingFunction easingFunction)
+        {{
+            _keyFrames.Insert(normalizedProgressKey, value, easingFunction);
+        }}
+        
+        public void InsertKeyFrame(float normalizedProgressKey, {a.Type} value)
+        {{
+            _keyFrames.Insert(normalizedProgressKey, value, Compositor.DefaultEasing);
+        }}
+    }}
+
+    public partial class Compositor
+    {{
+        public {name}KeyFrameAnimation Create{name}KeyFrameAnimation() => new {name}KeyFrameAnimation(this);
+    }}
+";
+            }
+
+            code += "}";
+            _output.AddSource("CompositionAnimations.cs", code);
+        }
+    }
+}

src/Avalonia.SourceGenerator/CompositionGenerator/Generator.ListProxy.cs

@@ -0,0 +1,121 @@
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+namespace Avalonia.SourceGenerator.CompositionGenerator
+{
+    public partial class Generator
+    {
+        private const string ListProxyTemplate = @"
+class Template
+{
+        private ServerListProxyHelper<ItemTypeName, ServerItemTypeName> _list = null!;
+
+        ListChangeSet<ServerItemTypeName>
+            ServerListProxyHelper<ItemTypeName, ServerItemTypeName>.IGetChanges.
+            GetChanges() => Changes;
+
+        public List<ItemTypeName>.Enumerator GetEnumerator() => _list.GetEnumerator();
+
+        IEnumerator<ItemTypeName> IEnumerable<ItemTypeName>.GetEnumerator() =>
+            GetEnumerator();
+        
+        IEnumerator IEnumerable.GetEnumerator() => ((IEnumerable) _list).GetEnumerator();
+
+        public void Add(ItemTypeName item)
+        {
+            OnBeforeAdded(item);
+            _list.Add(item);
+            OnAdded(item);
+        }
+
+        public void Clear()
+        {
+            OnBeforeClear();
+            _list.Clear();
+            OnClear();
+        }
+
+        public bool Contains(ItemTypeName item) => _list.Contains(item);
+
+        public void CopyTo(ItemTypeName[] array, int arrayIndex) => _list.CopyTo(array, arrayIndex);
+
+        public bool Remove(ItemTypeName item)
+        {
+            var removed = _list.Remove(item);
+            if(removed)
+                OnRemoved(item);
+            return removed;
+        }
+
+        public int Count => _list.Count;
+
+        public bool IsReadOnly => _list.IsReadOnly;
+
+        public int IndexOf(ItemTypeName item) => _list.IndexOf(item);
+
+        public void Insert(int index, ItemTypeName item)
+        {
+            OnBeforeAdded(item);
+            _list.Insert(index, item);
+            OnAdded(item);
+        }
+
+        public void RemoveAt(int index)
+        {
+            var item = _list[index];
+            _list.RemoveAt(index);
+            OnRemoved(item);
+        }
+
+        public ItemTypeName this[int index]
+        {
+            get => _list[index];
+            set
+            {
+                var old = _list[index];
+                OnBeforeReplace(old, value);
+                _list[index] = value;
+                OnReplace(old, value);
+            }
+        }
+
+        partial void OnBeforeAdded(ItemTypeName item);
+        partial void OnAdded(ItemTypeName item);
+        partial void OnRemoved(ItemTypeName item);
+        partial void OnBeforeClear();
+        partial void OnBeforeReplace(ItemTypeName oldItem, ItemTypeName newItem);
+        partial void OnReplace(ItemTypeName oldItem, ItemTypeName newItem);
+        partial void OnClear();
+}
+";
+
+        private ClassDeclarationSyntax AppendListProxy(GList list, ClassDeclarationSyntax cl)
+        {
+
+            var itemType = list.ItemType;
+            var serverItemType = ServerName(itemType);
+
+            cl = cl.AddBaseListTypes(SimpleBaseType(
+                    ParseTypeName("ServerListProxyHelper<" + itemType + ", " + serverItemType + ">.IGetChanges")),
+                SimpleBaseType(ParseTypeName("IList<" + itemType + ">"))
+            );
+            var code = ListProxyTemplate.Replace("ListTypeName", list.Name)
+                .Replace("ItemTypeName", itemType);
+
+            var parsed = ParseCompilationUnit(code);
+            var parsedClass = (ClassDeclarationSyntax)parsed.Members.First();
+
+            cl = cl.AddMembers(parsedClass.Members.ToArray());
+
+            var defs = cl.Members.OfType<MethodDeclarationSyntax>().First(m => m.Identifier.Text == "InitializeDefaults");
+
+            cl = cl.ReplaceNode(defs.Body, defs.Body.AddStatements(
+
+                ParseStatement($"_list = new ServerListProxyHelper<{itemType}, {serverItemType}>(this);")));
+          
+            return cl;
+        }
+        
+    }
+}

src/Avalonia.SourceGenerator/CompositionGenerator/Generator.Utils.cs

@@ -0,0 +1,66 @@
+using System.IO;
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+namespace Avalonia.SourceGenerator.CompositionGenerator
+{
+    public partial class Generator
+    {
+        static void CleanDirectory(string path)
+        {
+            Directory.CreateDirectory(path);
+            Directory.Delete(path, true);
+            Directory.CreateDirectory(path);
+        }
+        
+        CompilationUnitSyntax Unit()
+            => CompilationUnit().WithUsings(List(new[]
+                {
+                    "System",
+                    "System.Text",
+                    "System.Collections",
+                    "System.Collections.Generic"
+                }
+                .Concat(_config.Usings
+                    .Select(x => x.Name)).Select(u => UsingDirective(IdentifierName(u)))));
+        
+        void SaveTo(CompilationUnitSyntax unit, params string[] path)
+        {
+            var text = @"
+#nullable enable
+#pragma warning disable CS0108, CS0114
+
+" +
+
+                       unit.NormalizeWhitespace().ToFullString();
+            _output.AddSource(string.Join("_", path), text);
+        }
+        
+        
+        SyntaxToken Semicolon() => Token(SyntaxKind.SemicolonToken);
+
+        
+        FieldDeclarationSyntax DeclareConstant(string type, string name, LiteralExpressionSyntax value)
+            => FieldDeclaration(
+                    VariableDeclaration(ParseTypeName(type),
+                        SingletonSeparatedList(
+                            VariableDeclarator(name).WithInitializer(EqualsValueClause(value))
+                        ))
+                ).WithSemicolonToken(Semicolon())
+                .WithModifiers(TokenList(Token(SyntaxKind.PublicKeyword), Token(SyntaxKind.ConstKeyword)));
+
+        FieldDeclarationSyntax DeclareField(string type, string name, params SyntaxKind[] modifiers) =>
+            DeclareField(type, name, null, modifiers);
+
+        FieldDeclarationSyntax DeclareField(string type, string name, EqualsValueClauseSyntax initializer,
+            params SyntaxKind[] modifiers) =>
+            FieldDeclaration(
+                    VariableDeclaration(ParseTypeName(type),
+                        SingletonSeparatedList(
+                            VariableDeclarator(name).WithInitializer(initializer))))
+                .WithSemicolonToken(Semicolon())
+                .WithModifiers(TokenList(modifiers.Select(x => Token(x))));
+    }
+}

src/Avalonia.SourceGenerator/CompositionGenerator/Generator.cs

@@ -0,0 +1,504 @@
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+using static Avalonia.SourceGenerator.CompositionGenerator.Extensions;
+namespace Avalonia.SourceGenerator.CompositionGenerator
+{
+    partial class Generator
+    {
+        private readonly SourceProductionContext _output;
+        private readonly GConfig _config;
+        private readonly HashSet<string> _objects;
+        private readonly HashSet<string> _brushes;
+        private readonly Dictionary<string, GManualClass> _manuals;
+        public Generator(SourceProductionContext output, GConfig config)
+        {
+            _output = output;
+            _config = config;
+            _manuals = _config.ManualClasses.ToDictionary(x => x.Name);
+            _objects = new HashSet<string>(_config.ManualClasses.Select(x => x.Name)
+                .Concat(_config.Classes.Select(x => x.Name)));
+            _brushes = new HashSet<string>(_config.Classes.OfType<GBrush>().Select(x => x.Name)) {"CompositionBrush"};
+        }
+
+        
+        
+        public void Generate()
+        {
+            foreach (var cl in _config.Classes)
+                GenerateClass(cl);
+            
+            GenerateAnimations();
+        }
+
+
+
+        string ServerName(string c) => c != null ? ("Server" + c) : "ServerObject";
+        string ChangesName(string c) => c != null ? (c + "Changes") : "ChangeSet";
+        
+        void GenerateClass(GClass cl)
+        {
+            var list = cl as GList;
+            
+            var unit = Unit();
+            
+            var clientNs = NamespaceDeclaration(IdentifierName("Avalonia.Rendering.Composition"));
+            var serverNs = NamespaceDeclaration(IdentifierName("Avalonia.Rendering.Composition.Server"));
+            var transportNs = NamespaceDeclaration(IdentifierName("Avalonia.Rendering.Composition.Transport"));
+
+            var inherits = cl.Inherits ?? "CompositionObject";
+            var abstractModifier = cl.Abstract ? new[] {SyntaxKind.AbstractKeyword} : null;
+            
+            var client = ClassDeclaration(cl.Name)
+                .AddModifiers(abstractModifier)
+                .AddModifiers(SyntaxKind.PublicKeyword, SyntaxKind.UnsafeKeyword, SyntaxKind.PartialKeyword)
+                .WithBaseType(inherits);
+            
+            var serverName = ServerName(cl.Name);
+            var serverBase = cl.ServerBase ?? ServerName(cl.Inherits);
+            if (list != null)
+                serverBase = "ServerList<" + ServerName(list.ItemType) + ">";
+            
+            var server = ClassDeclaration(serverName)
+                .AddModifiers(abstractModifier)
+                .AddModifiers(SyntaxKind.UnsafeKeyword, SyntaxKind.PartialKeyword)
+                .WithBaseType(serverBase);
+
+            string changesName = ChangesName(cl.Name);
+            var changesBase = ChangesName(cl.ChangesBase ?? cl.Inherits);
+
+            if (list != null)
+                changesBase = "ListChangeSet<" + ServerName(list.ItemType) + ">";
+
+            var changeSetPoolType = "ChangeSetPool<" + changesName + ">";
+            var transport = ClassDeclaration(changesName)
+                .AddModifiers(SyntaxKind.UnsafeKeyword, SyntaxKind.PartialKeyword)
+                .WithBaseType(changesBase)
+                .AddMembers(DeclareField(changeSetPoolType, "Pool",
+                    EqualsValueClause(
+                        ParseExpression($"new {changeSetPoolType}(pool => new {changesName}(pool))")
+                    ),
+                    SyntaxKind.PublicKeyword,
+                    SyntaxKind.StaticKeyword, SyntaxKind.ReadOnlyKeyword))
+                .AddMembers(ParseMemberDeclaration($"public {changesName}(IChangeSetPool pool) : base(pool){{}}"));
+
+            client = client
+                .AddMembers(
+                    PropertyDeclaration(ParseTypeName("IChangeSetPool"), "ChangeSetPool")
+                    .AddModifiers(SyntaxKind.PrivateKeyword, SyntaxKind.ProtectedKeyword,
+                            SyntaxKind.OverrideKeyword)
+                        .WithExpressionBody(
+                            ArrowExpressionClause(MemberAccess(changesName, "Pool")))
+                        .WithSemicolonToken(Semicolon()))
+                .AddMembers(PropertyDeclaration(ParseTypeName(changesName), "Changes")
+                    .AddModifiers(SyntaxKind.PrivateKeyword, SyntaxKind.NewKeyword)
+                    .WithExpressionBody(ArrowExpressionClause(CastExpression(ParseTypeName(changesName),
+                        MemberAccess(BaseExpression(), "Changes"))))
+                    .WithSemicolonToken(Semicolon()));
+            
+            if (!cl.CustomCtor)
+            {
+                client = client.AddMembers(PropertyDeclaration(ParseTypeName(serverName), "Server")
+                    .AddModifiers(SyntaxKind.InternalKeyword, SyntaxKind.NewKeyword)
+                    .AddAccessorListAccessors(AccessorDeclaration(SyntaxKind.GetAccessorDeclaration)
+                        .WithSemicolonToken(Semicolon())));
+                client = client.AddMembers(
+                    ConstructorDeclaration(cl.Name)
+                        .AddModifiers(SyntaxKind.InternalKeyword)
+                        .WithParameterList(ParameterList(SeparatedList(new[]
+                        {
+                            Parameter(Identifier("compositor")).WithType(ParseTypeName("Compositor")),
+                            Parameter(Identifier("server")).WithType(ParseTypeName(serverName)),
+                        })))
+                        .WithInitializer(ConstructorInitializer(SyntaxKind.BaseConstructorInitializer,
+                            ArgumentList(SeparatedList(new[]
+                            {
+                                Argument(IdentifierName("compositor")),
+                                Argument(IdentifierName("server")),
+                            })))).WithBody(Block(
+                            ExpressionStatement(
+                                AssignmentExpression(
+                                    SyntaxKind.SimpleAssignmentExpression,
+                                    IdentifierName("Server"),
+                                    CastExpression(ParseTypeName(serverName), IdentifierName("server")))),
+                            ExpressionStatement(InvocationExpression(IdentifierName("InitializeDefaults")))
+                        )));
+            }
+
+            if (!cl.CustomServerCtor)
+            {
+                server = server.AddMembers(
+                    ConstructorDeclaration(serverName)
+                        .AddModifiers(SyntaxKind.InternalKeyword)
+                        .WithParameterList(ParameterList(SeparatedList(new[]
+                        {
+                            Parameter(Identifier("compositor")).WithType(ParseTypeName("ServerCompositor")),
+                        })))
+                        .WithInitializer(ConstructorInitializer(SyntaxKind.BaseConstructorInitializer,
+                            ArgumentList(SeparatedList(new[]
+                            {
+                                Argument(IdentifierName("compositor")),
+                            })))).WithBody(Block()));
+            }
+
+
+            var changesVarName = "c";
+            var changesVar = IdentifierName(changesVarName);
+
+            server = server.AddMembers(
+                MethodDeclaration(ParseTypeName("void"), "ApplyChangesExtra")
+                    .AddParameterListParameters(Parameter(Identifier("c")).WithType(ParseTypeName(changesName)))
+                    .AddModifiers(SyntaxKind.PartialKeyword).WithSemicolonToken(Semicolon()));
+            
+            transport = transport.AddMembers(
+                MethodDeclaration(ParseTypeName("void"), "ResetExtra")
+                    .AddModifiers(SyntaxKind.PartialKeyword).WithSemicolonToken(Semicolon()));
+
+            var applyMethodBody = Block(
+                ExpressionStatement(InvocationExpression(MemberAccess(IdentifierName("base"), "ApplyCore"),
+                    ArgumentList(SeparatedList(new[] {Argument(IdentifierName("changes"))})))),
+                LocalDeclarationStatement(VariableDeclaration(ParseTypeName("var"))
+                    .WithVariables(SingletonSeparatedList(
+                        VariableDeclarator(changesVarName)
+                            .WithInitializer(EqualsValueClause(CastExpression(ParseTypeName(changesName),
+                                IdentifierName("changes"))))))),
+                ExpressionStatement(InvocationExpression(IdentifierName("ApplyChangesExtra"))
+                    .AddArgumentListArguments(Argument(IdentifierName("c"))))
+            );
+
+            var resetBody = Block();
+            var startAnimationBody = Block();
+            var getPropertyBody = Block();
+            var serverGetPropertyBody = Block();
+
+            var defaultsMethodBody = Block();
+            
+            foreach (var prop in cl.Properties)
+            {
+                var fieldName = "_" + prop.Name.WithLowerFirst();
+                var propType = ParseTypeName(prop.Type);
+                var filteredPropertyType = prop.Type.TrimEnd('?');
+                var isObject = _objects.Contains(filteredPropertyType);
+                var isNullable = prop.Type.EndsWith("?");
+                
+
+
+
+                client = client
+                    .AddMembers(DeclareField(prop.Type, fieldName))
+                    .AddMembers(PropertyDeclaration(propType, prop.Name)
+                        .AddModifiers(SyntaxKind.PublicKeyword)
+                        .AddAccessorListAccessors(
+                            AccessorDeclaration(SyntaxKind.GetAccessorDeclaration,
+                                Block(ReturnStatement(IdentifierName(fieldName)))),
+                            AccessorDeclaration(SyntaxKind.SetAccessorDeclaration,
+                                Block(
+                                    ParseStatement("var changed = false;"),
+                                    IfStatement(BinaryExpression(SyntaxKind.NotEqualsExpression,
+                                            IdentifierName(fieldName),
+                                            IdentifierName("value")),
+                                        Block(
+                                            ParseStatement("On" + prop.Name + "Changing();"),
+                                            ParseStatement("changed = true;"),
+                                            GeneratePropertySetterAssignment(prop, fieldName, isObject, isNullable))
+                                    ),
+                                    ExpressionStatement(AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
+                                        IdentifierName(fieldName), IdentifierName("value"))),
+                                    ParseStatement($"if(changed) On" + prop.Name + "Changed();")
+                                ))
+                        ))
+                    .AddMembers(MethodDeclaration(ParseTypeName("void"), "On" + prop.Name + "Changed")
+                        .AddModifiers(SyntaxKind.PartialKeyword).WithSemicolonToken(Semicolon()))
+                    .AddMembers(MethodDeclaration(ParseTypeName("void"), "On" + prop.Name + "Changing")
+                        .AddModifiers(SyntaxKind.PartialKeyword).WithSemicolonToken(Semicolon()));
+
+
+                var animatedServer = prop.Animated;
+                
+                var serverPropertyType = ((isObject ? "Server" : "") + prop.Type);
+                if (_manuals.TryGetValue(filteredPropertyType, out var manual) && manual.ServerName != null)
+                    serverPropertyType = manual.ServerName + (isNullable ? "?" : "");
+                
+
+                transport = transport
+                    .AddMembers(DeclareField((animatedServer ? "Animated" : "") + "Change<" + serverPropertyType + ">",
+                        prop.Name, SyntaxKind.PublicKeyword));
+
+                if (animatedServer)
+                    server = server.AddMembers(
+                        DeclareField("AnimatedValueStore<" + serverPropertyType + ">", fieldName),
+                        PropertyDeclaration(ParseTypeName(serverPropertyType), prop.Name)
+                            .AddModifiers(SyntaxKind.PublicKeyword)
+                            .WithExpressionBody(ArrowExpressionClause(
+                                InvocationExpression(MemberAccess(fieldName, "GetAnimated"),
+                                    ArgumentList(SingletonSeparatedList(Argument(IdentifierName("Compositor")))))))
+                            .WithSemicolonToken(Semicolon())
+                    );
+                else
+                {
+                    server = server
+                        .AddMembers(DeclareField(serverPropertyType, fieldName))
+                        .AddMembers(PropertyDeclaration(ParseTypeName(serverPropertyType), prop.Name)
+                            .AddModifiers(SyntaxKind.PublicKeyword)
+                            .AddAccessorListAccessors(
+                                AccessorDeclaration(SyntaxKind.GetAccessorDeclaration,
+                                    Block(ReturnStatement(IdentifierName(fieldName)))),
+                                AccessorDeclaration(SyntaxKind.SetAccessorDeclaration,
+                                    Block(
+                                        ParseStatement("var changed = false;"),
+                                        IfStatement(BinaryExpression(SyntaxKind.NotEqualsExpression,
+                                                IdentifierName(fieldName),
+                                                IdentifierName("value")),
+                                            Block(
+                                                ParseStatement("On" + prop.Name + "Changing();"),
+                                                ParseStatement($"changed = true;"))
+                                        ),
+                                        ExpressionStatement(AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
+                                            IdentifierName(fieldName), IdentifierName("value"))),
+                                        ParseStatement($"if(changed) On" + prop.Name + "Changed();")
+                                    ))
+                            ))
+                        .AddMembers(MethodDeclaration(ParseTypeName("void"), "On" + prop.Name + "Changed")
+                            .AddModifiers(SyntaxKind.PartialKeyword).WithSemicolonToken(Semicolon()))
+                        .AddMembers(MethodDeclaration(ParseTypeName("void"), "On" + prop.Name + "Changing")
+                            .AddModifiers(SyntaxKind.PartialKeyword).WithSemicolonToken(Semicolon()));
+                }
+
+                if (animatedServer)
+                    applyMethodBody = applyMethodBody.AddStatements(
+                        IfStatement(MemberAccess(changesVar, prop.Name, "IsValue"),
+                            ExpressionStatement(AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
+                                IdentifierName(fieldName), MemberAccess(changesVar, prop.Name, "Value")))),
+                        IfStatement(MemberAccess(changesVar, prop.Name, "IsAnimation"),
+                            ExpressionStatement(
+                                InvocationExpression(MemberAccess(fieldName, "SetAnimation"),
+                                    ArgumentList(SeparatedList(new[]
+                                    {
+                                        Argument(changesVar),
+                                        Argument(MemberAccess(changesVar, prop.Name, "Animation"))
+                                    })))))
+                    );
+                else
+                    applyMethodBody = applyMethodBody.AddStatements(
+                        IfStatement(MemberAccess(changesVar, prop.Name, "IsSet"),
+                            ExpressionStatement(AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
+                                IdentifierName(prop.Name), MemberAccess(changesVar, prop.Name, "Value"))))
+
+                    );
+                
+
+                resetBody = resetBody.AddStatements(
+                    ExpressionStatement(InvocationExpression(MemberAccess(prop.Name, "Reset"))));
+
+                if (animatedServer)
+                    startAnimationBody = ApplyStartAnimation(startAnimationBody, prop, fieldName);
+
+                getPropertyBody = ApplyGetProperty(getPropertyBody, prop);
+                serverGetPropertyBody = ApplyGetProperty(getPropertyBody, prop);
+                
+                if (prop.DefaultValue != null)
+                {
+                    defaultsMethodBody = defaultsMethodBody.AddStatements(
+                        ExpressionStatement(
+                            AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
+                                IdentifierName(prop.Name), ParseExpression(prop.DefaultValue))));
+                }
+            }
+
+            if (cl is GBrush brush && !cl.Abstract)
+            {
+                var brushName = brush.Name.StripPrefix("Composition");
+                /*
+                server = server.AddMembers(
+                    MethodDeclaration(ParseTypeName("ICbBrush"), "CreateBackendBrush")
+                        .AddModifiers(SyntaxKind.ProtectedKeyword, SyntaxKind.OverrideKeyword)
+                        .WithExpressionBody(ArrowExpressionClause(
+                            InvocationExpression(MemberAccess("Compositor", "Backend", "Create" + brushName))
+                        )).WithSemicolonToken(Semicolon())
+                );
+                if (!brush.CustomUpdate)
+                    server = server.AddMembers(
+                        MethodDeclaration(ParseTypeName("void"), "UpdateBackendBrush")
+                            .AddModifiers(SyntaxKind.ProtectedKeyword, SyntaxKind.OverrideKeyword)
+                            .AddParameterListParameters(Parameter(Identifier("brush"))
+                                .WithType(ParseTypeName("ICbBrush")))
+                            .AddBodyStatements(
+                                ExpressionStatement(
+                                    InvocationExpression(
+                                        MemberAccess(
+                                            ParenthesizedExpression(
+                                            CastExpression(ParseTypeName("ICb" + brushName), IdentifierName("brush"))), "Update"),
+                                        ArgumentList(SeparatedList(cl.Properties.Select(x =>
+                                        {
+                                            if(x.Type.TrimEnd('?') == "ICompositionSurface")
+                                                return Argument(
+                                                    ConditionalAccessExpression(IdentifierName(x.Name),
+                                                        MemberBindingExpression(IdentifierName("BackendSurface")))
+                                                );
+                                            if (_brushes.Contains(x.Type))
+                                                return Argument(
+                                                    ConditionalAccessExpression(IdentifierName(x.Name),
+                                                        MemberBindingExpression(IdentifierName("Brush")))
+                                                );
+                                            return Argument(IdentifierName(x.Name));
+                                        }))))
+                                )));
+
+*/
+            }
+            
+            server = server.AddMembers(
+                MethodDeclaration(ParseTypeName("void"), "ApplyCore")
+                    .AddModifiers(SyntaxKind.ProtectedKeyword, SyntaxKind.OverrideKeyword)
+                    .AddParameterListParameters(
+                        Parameter(Identifier("changes")).WithType(ParseTypeName("ChangeSet")))
+                    .WithBody(applyMethodBody));
+
+            client = client.AddMembers(
+                MethodDeclaration(ParseTypeName("void"), "InitializeDefaults").WithBody(defaultsMethodBody));
+
+            transport = transport.AddMembers(MethodDeclaration(ParseTypeName("void"), "Reset")
+                .AddModifiers(SyntaxKind.PublicKeyword, SyntaxKind.OverrideKeyword)
+                .WithBody(resetBody.AddStatements(
+                    ExpressionStatement(InvocationExpression(IdentifierName("ResetExtra"))),
+                    ExpressionStatement(InvocationExpression(MemberAccess("base", "Reset"))))));
+
+            if (list != null)
+                client = AppendListProxy(list, client);
+
+            if (startAnimationBody.Statements.Count != 0)
+                client = WithStartAnimation(client, startAnimationBody);
+
+            client = WithGetProperty(client, getPropertyBody, false);
+            server = WithGetProperty(server, serverGetPropertyBody, true);
+            
+            if(cl.Implements.Count > 0)
+                foreach (var impl in cl.Implements)
+                {
+                    client = client.WithBaseList(client.BaseList.AddTypes(SimpleBaseType(ParseTypeName(impl.Name))));
+                    if (impl.ServerName != null)
+                        server = server.WithBaseList(
+                            server.BaseList.AddTypes(SimpleBaseType(ParseTypeName(impl.ServerName))));
+
+                    client = client.AddMembers(
+                        ParseMemberDeclaration($"{impl.ServerName} {impl.Name}.Server => Server;"));
+                }
+
+
+            SaveTo(unit.AddMembers(clientNs.AddMembers(client)),
+                cl.Name + ".generated.cs");
+            SaveTo(unit.AddMembers(serverNs.AddMembers(server)),
+                "Server", "Server" + cl.Name + ".generated.cs");
+            SaveTo(unit.AddMembers(transportNs.AddMembers(transport)),
+                "Transport",  cl.Name + "Changes.generated.cs");
+        }
+
+        StatementSyntax GeneratePropertySetterAssignment(GProperty prop, string fieldName, bool isObject, bool isNullable)
+        {
+            var normalChangesAssignment = (StatementSyntax)ExpressionStatement(AssignmentExpression(
+                SyntaxKind.SimpleAssignmentExpression,
+                MemberAccess((ExpressionSyntax) IdentifierName("Changes"), prop.Name,
+                    "Value"),
+                isObject
+                    ?  
+                    ConditionalMemberAccess(IdentifierName("value"), "Server", isNullable)
+                    : IdentifierName("value")));
+            if (!prop.Animated)
+                return normalChangesAssignment;
+
+            var code = $@"
+{{
+    if(animation is CompositionAnimation a)
+        Changes.{prop.Name}.Animation = a.CreateInstance(this.Server, value);
+    else
+    {{
+        var saved = Changes.{prop.Name};
+        if(!StartAnimationGroup(animation, ""{prop.Name}"", value))
+            Changes.{prop.Name}.Value = value;
+    }}
+}}
+
+";
+            
+            return IfStatement(
+                ParseExpression(
+                    $"ImplicitAnimations != null && ImplicitAnimations.TryGetValue(\"{prop.Name}\", out var animation) == true"),
+                ParseStatement(code),
+                ElseClause(normalChangesAssignment)
+            );
+        }
+        
+        BlockSyntax ApplyStartAnimation(BlockSyntax body, GProperty prop, string fieldName)
+        {
+            var code = $@"
+if (propertyName == ""{prop.Name}"")
+{{
+var current = {fieldName};
+var server = animation.CreateInstance(this.Server, finalValue);
+Changes.{prop.Name}.Animation = server;
+return;
+}}
+";
+            return body.AddStatements(ParseStatement(code));
+        }
+
+        private static HashSet<string> VariantPropertyTypes = new HashSet<string>
+        {
+            "bool",
+            "float",
+            "Vector2",
+            "Vector3",
+            "Vector4",
+            "Matrix3x2",
+            "Matrix4x4",
+            "Quaternion",
+            "CompositionColor"
+        };
+        
+        BlockSyntax ApplyGetProperty(BlockSyntax body, GProperty prop)
+        {
+            if (VariantPropertyTypes.Contains(prop.Type))
+                return body.AddStatements(
+                    ParseStatement($"if(name == \"{prop.Name}\")\n return {prop.Name};\n")
+                );
+
+            return body;
+        }
+
+        ClassDeclarationSyntax WithGetProperty(ClassDeclarationSyntax cl, BlockSyntax body, bool server)
+        {
+            if (body.Statements.Count == 0)
+                return cl;
+            body = body.AddStatements(
+                ParseStatement("return base.GetPropertyForAnimation(name);"));
+            var method = ((MethodDeclarationSyntax) ParseMemberDeclaration(
+                    $"{(server ? "public" : "internal")} override Avalonia.Rendering.Composition.Expressions.ExpressionVariant GetPropertyForAnimation(string name){{}}"))
+                .WithBody(body);
+
+            return cl.AddMembers(method);
+        }
+
+        ClassDeclarationSyntax WithStartAnimation(ClassDeclarationSyntax cl, BlockSyntax body)
+        {
+            body = body.AddStatements(
+                ExpressionStatement(InvocationExpression(MemberAccess("base", "StartAnimation"),
+                    ArgumentList(SeparatedList(new[]
+                    {
+                        Argument(IdentifierName("propertyName")),
+                        Argument(IdentifierName("animation")),
+                        Argument(IdentifierName("finalValue")),
+                    }))))
+            );
+            return cl.AddMembers(
+                ((MethodDeclarationSyntax) ParseMemberDeclaration(
+                    "internal override void StartAnimation(string propertyName, CompositionAnimation animation, Avalonia.Rendering.Composition.Expressions.ExpressionVariant? finalValue){}"))
+                .WithBody(body));
+
+
+        }
+        
+    }
+}

src/Avalonia.X11/X11Platform.cs

@@ -13,6 +13,7 @@ using Avalonia.OpenGL;
 using Avalonia.OpenGL.Egl;
 using Avalonia.Platform;
 using Avalonia.Rendering;
+using Avalonia.Rendering.Composition;
 using Avalonia.X11;
 using Avalonia.X11.Glx;
 using Avalonia.X11.NativeDialogs;
@@ -29,6 +30,7 @@ namespace Avalonia.X11
         public XI2Manager XI2;
         public X11Info Info { get; private set; }
         public IX11Screens X11Screens { get; private set; }
+        public Compositor Compositor { get; private set; }
         public IScreenImpl Screens { get; private set; }
         public X11PlatformOptions Options { get; private set; }
         public IntPtr OrphanedWindow { get; private set; }
@@ -101,7 +103,9 @@ namespace Avalonia.X11
                     GlxPlatformOpenGlInterface.TryInitialize(Info, Options.GlProfiles);
             }
 
-            
+            if (options.UseCompositor)
+                Compositor = Compositor.Create(AvaloniaLocator.Current.GetService<IRenderLoop>()!);
+
         }
 
         public IntPtr DeferredDisplay { get; set; }
@@ -222,6 +226,8 @@ namespace Avalonia
         /// Immediate re-renders the whole scene when some element is changed on the scene. Deferred re-renders only changed elements.
         /// </remarks>
         public bool UseDeferredRendering { get; set; } = true;
+        
+        public bool UseCompositor { get; set; }
 
         /// <summary>
         /// Determines whether to use IME.

src/Avalonia.X11/X11Window.cs

@@ -18,6 +18,7 @@ using Avalonia.OpenGL;
 using Avalonia.OpenGL.Egl;
 using Avalonia.Platform;
 using Avalonia.Rendering;
+using Avalonia.Rendering.Composition;
 using Avalonia.Threading;
 using Avalonia.X11.Glx;
 using static Avalonia.X11.XLib;
@@ -360,13 +361,15 @@ namespace Avalonia.X11
 
             if (customRendererFactory != null)
                 return customRendererFactory.Create(root, loop);
-            
+
-            return _platform.Options.UseDeferredRendering ?
+            return _platform.Options.UseDeferredRendering
-                new DeferredRenderer(root, loop)
+                ? _platform.Options.UseCompositor
-                {
+                    ? new CompositingRenderer(root, this._platform.Compositor)
-                    RenderOnlyOnRenderThread = true
+                    : new DeferredRenderer(root, loop)
-                } :
+                    {
-                (IRenderer)new X11ImmediateRendererProxy(root, loop);
+                        RenderOnlyOnRenderThread = true
+                    }
+                : (IRenderer)new X11ImmediateRendererProxy(root, loop);
         }
 
         void OnEvent(ref XEvent ev)

src/Windows/Avalonia.Direct2D1/Media/DrawingContextImpl.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Numerics;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Rendering;
@@ -73,6 +74,12 @@ namespace Avalonia.Direct2D1.Media
             set { _deviceContext.Transform = value.ToDirect2D(); }
         }
 
+        public Matrix4x4 Transform4x4
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
         /// <inheritdoc/>
         public void Clear(Color color)
         {