Merge pull request #8036 from amwx/BrushRelativeTransform

Add `TransformOrigin` to Brushes

src/Avalonia.Base/Animation/Animators/GradientBrushAnimator.cs

@@ -31,6 +31,7 @@ namespace Avalonia.Animation.Animators
                         InterpolateStops(progress, oldValue.GradientStops, newValue.GradientStops),
                         s_doubleAnimator.Interpolate(progress, oldValue.Opacity, newValue.Opacity),
                         oldValue.Transform is { } ? new ImmutableTransform(oldValue.Transform.Value) : null,
+                        s_relativePointAnimator.Interpolate(progress, oldValue.TransformOrigin, newValue.TransformOrigin),
                         oldValue.SpreadMethod,
                         s_relativePointAnimator.Interpolate(progress, oldRadial.Center, newRadial.Center),
                         s_relativePointAnimator.Interpolate(progress, oldRadial.GradientOrigin, newRadial.GradientOrigin),
@@ -41,6 +42,7 @@ namespace Avalonia.Animation.Animators
                         InterpolateStops(progress, oldValue.GradientStops, newValue.GradientStops),
                         s_doubleAnimator.Interpolate(progress, oldValue.Opacity, newValue.Opacity),
                         oldValue.Transform is { } ? new ImmutableTransform(oldValue.Transform.Value) : null,
+                        s_relativePointAnimator.Interpolate(progress, oldValue.TransformOrigin, newValue.TransformOrigin),
                         oldValue.SpreadMethod,
                         s_relativePointAnimator.Interpolate(progress, oldConic.Center, newConic.Center),
                         s_doubleAnimator.Interpolate(progress, oldConic.Angle, newConic.Angle));
@@ -50,6 +52,7 @@ namespace Avalonia.Animation.Animators
                         InterpolateStops(progress, oldValue.GradientStops, newValue.GradientStops),
                         s_doubleAnimator.Interpolate(progress, oldValue.Opacity, newValue.Opacity),
                         oldValue.Transform is { } ? new ImmutableTransform(oldValue.Transform.Value) : null,
+                        s_relativePointAnimator.Interpolate(progress, oldValue.TransformOrigin, newValue.TransformOrigin),
                         oldValue.SpreadMethod,
                         s_relativePointAnimator.Interpolate(progress, oldLinear.StartPoint, newLinear.StartPoint),
                         s_relativePointAnimator.Interpolate(progress, oldLinear.EndPoint, newLinear.EndPoint));
@@ -102,18 +105,21 @@ namespace Avalonia.Animation.Animators
                     return new ImmutableRadialGradientBrush(
                         CreateStopsFromSolidColorBrush(solidColorBrush, oldRadial.GradientStops), solidColorBrush.Opacity,
                         oldRadial.Transform is { } ? new ImmutableTransform(oldRadial.Transform.Value) : null,
+                        oldRadial.TransformOrigin,
                         oldRadial.SpreadMethod, oldRadial.Center, oldRadial.GradientOrigin, oldRadial.Radius);
 
                 case IConicGradientBrush oldConic:
                     return new ImmutableConicGradientBrush(
                         CreateStopsFromSolidColorBrush(solidColorBrush, oldConic.GradientStops), solidColorBrush.Opacity,
                         oldConic.Transform is { } ? new ImmutableTransform(oldConic.Transform.Value) : null,
+                        oldConic.TransformOrigin,
                         oldConic.SpreadMethod, oldConic.Center, oldConic.Angle);
 
                 case ILinearGradientBrush oldLinear:
                     return new ImmutableLinearGradientBrush(
                         CreateStopsFromSolidColorBrush(solidColorBrush, oldLinear.GradientStops), solidColorBrush.Opacity,
                         oldLinear.Transform is { } ? new ImmutableTransform(oldLinear.Transform.Value) : null,
+                        oldLinear.TransformOrigin,
                         oldLinear.SpreadMethod, oldLinear.StartPoint, oldLinear.EndPoint);
 
                 default:

src/Avalonia.Base/Media/Brush.cs

@@ -24,6 +24,12 @@ namespace Avalonia.Media
         public static readonly StyledProperty<ITransform?> TransformProperty =
             AvaloniaProperty.Register<Brush, ITransform?>(nameof(Transform));
 
+        /// <summary>
+        /// Defines the <see cref="TransformOrigin"/> property
+        /// </summary>
+        public static readonly StyledProperty<RelativePoint> TransformOriginProperty =
+            AvaloniaProperty.Register<Brush, RelativePoint>(nameof(TransformOrigin));
+
         /// <inheritdoc/>
         public event EventHandler? Invalidated;
 
@@ -51,6 +57,15 @@ namespace Avalonia.Media
             set { SetValue(TransformProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the origin of the brush <see cref="Transform"/>
+        /// </summary>
+        public RelativePoint TransformOrigin
+        {
+            get => GetValue(TransformOriginProperty);
+            set => SetValue(TransformOriginProperty, value);
+        }
+
         /// <summary>
         /// Parses a brush string.
         /// </summary>

src/Avalonia.Base/Media/IBrush.cs

@@ -19,5 +19,10 @@ namespace Avalonia.Media
         /// Gets the transform of the brush.
         /// </summary>
         ITransform? Transform { get; }
+
+        /// <summary>
+        /// Gets the origin of the brushes <see cref="Transform"/>
+        /// </summary>
+        RelativePoint TransformOrigin { get; }
     }
 }

src/Avalonia.Base/Media/Immutable/ImmutableConicGradientBrush.cs

@@ -13,6 +13,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="gradientStops">The gradient stops.</param>
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="transform">The transform of the brush.</param>
+        /// <param name="transformOrigin">The transform origin of the brush</param>
         /// <param name="spreadMethod">The spread method.</param>
         /// <param name="center">The center point for the gradient.</param>
         /// <param name="angle">The starting angle for the gradient.</param>
@@ -20,10 +21,11 @@ namespace Avalonia.Media.Immutable
             IReadOnlyList<ImmutableGradientStop> gradientStops,
             double opacity = 1,
             ImmutableTransform? transform = null,
+            RelativePoint? transformOrigin = null,
             GradientSpreadMethod spreadMethod = GradientSpreadMethod.Pad,
             RelativePoint? center = null,
             double angle = 0)
-            : base(gradientStops, opacity, transform, spreadMethod)
+            : base(gradientStops, opacity, transform, transformOrigin, spreadMethod)
         {
             Center = center ?? RelativePoint.Center;
             Angle = angle;

src/Avalonia.Base/Media/Immutable/ImmutableGradientBrush.cs

@@ -13,16 +13,19 @@ namespace Avalonia.Media.Immutable
         /// <param name="gradientStops">The gradient stops.</param>
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="transform">The transform of the brush.</param>
+        /// <param name="transformOrigin">The transform origin of the brush</param>
         /// <param name="spreadMethod">The spread method.</param>
         protected ImmutableGradientBrush(
             IReadOnlyList<ImmutableGradientStop> gradientStops,
             double opacity,
             ImmutableTransform? transform,
+            RelativePoint? transformOrigin,
             GradientSpreadMethod spreadMethod)
         {
             GradientStops = gradientStops;
             Opacity = opacity;
             Transform = transform;
+            TransformOrigin = transformOrigin.HasValue ? transformOrigin.Value : RelativePoint.TopLeft;
             SpreadMethod = spreadMethod;
         }
 
@@ -31,7 +34,8 @@ namespace Avalonia.Media.Immutable
         /// </summary>
         /// <param name="source">The brush from which this brush's properties should be copied.</param>
         protected ImmutableGradientBrush(GradientBrush source)
-            : this(source.GradientStops.ToImmutable(), source.Opacity, source.Transform?.ToImmutable(), source.SpreadMethod)
+            : this(source.GradientStops.ToImmutable(), source.Opacity, source.Transform?.ToImmutable(), 
+                  source.TransformOrigin, source.SpreadMethod)
         {
 
         }
@@ -47,6 +51,11 @@ namespace Avalonia.Media.Immutable
         /// </summary>
         public ITransform? Transform { get; }
 
+        /// <summary>
+        /// Gets the transform origin of the brush
+        /// </summary>
+        public RelativePoint TransformOrigin { get; }
+
         /// <inheritdoc/>
         public GradientSpreadMethod SpreadMethod { get; }
     }

src/Avalonia.Base/Media/Immutable/ImmutableImageBrush.cs

@@ -16,6 +16,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="destinationRect">The rectangle on the destination in which to paint a tile.</param>
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="transform">The transform of the brush.</param>
+        /// <param name="transformOrigin">The transform origin of the brush</param>
         /// <param name="sourceRect">The rectangle of the source image that will be displayed.</param>
         /// <param name="stretch">
         /// How the source rectangle will be stretched to fill the destination rect.
@@ -29,6 +30,7 @@ namespace Avalonia.Media.Immutable
             RelativeRect? destinationRect = null,
             double opacity = 1,
             ImmutableTransform? transform = null,
+            RelativePoint transformOrigin = new RelativePoint(),
             RelativeRect? sourceRect = null,
             Stretch stretch = Stretch.Uniform,
             TileMode tileMode = TileMode.None,
@@ -39,6 +41,7 @@ namespace Avalonia.Media.Immutable
                   destinationRect ?? RelativeRect.Fill,
                   opacity,
                   transform,
+                  transformOrigin,
                   sourceRect ?? RelativeRect.Fill,
                   stretch,
                   tileMode,

src/Avalonia.Base/Media/Immutable/ImmutableLinearGradientBrush.cs

@@ -13,6 +13,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="gradientStops">The gradient stops.</param>
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="transform">The transform of the brush.</param>
+        /// <param name="transformOrigin">The transform origin of the brush</param>
         /// <param name="spreadMethod">The spread method.</param>
         /// <param name="startPoint">The start point for the gradient.</param>
         /// <param name="endPoint">The end point for the gradient.</param>
@@ -20,10 +21,11 @@ namespace Avalonia.Media.Immutable
             IReadOnlyList<ImmutableGradientStop> gradientStops,
             double opacity = 1,
             ImmutableTransform? transform = null,
+            RelativePoint? transformOrigin = null,
             GradientSpreadMethod spreadMethod = GradientSpreadMethod.Pad,
             RelativePoint? startPoint = null,
             RelativePoint? endPoint = null)
-            : base(gradientStops, opacity, transform, spreadMethod)
+            : base(gradientStops, opacity, transform, transformOrigin, spreadMethod)
         {
             StartPoint = startPoint ?? RelativePoint.TopLeft;
             EndPoint = endPoint ?? RelativePoint.BottomRight;

src/Avalonia.Base/Media/Immutable/ImmutableRadialGradientBrush.cs

@@ -13,6 +13,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="gradientStops">The gradient stops.</param>
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="transform">The transform of the brush.</param>
+        /// <param name="transformOrigin">The transform origin of the brush</param>
         /// <param name="spreadMethod">The spread method.</param>
         /// <param name="center">The start point for the gradient.</param>
         /// <param name="gradientOrigin">
@@ -25,11 +26,12 @@ namespace Avalonia.Media.Immutable
             IReadOnlyList<ImmutableGradientStop> gradientStops,
             double opacity = 1,
             ImmutableTransform? transform = null,
+            RelativePoint? transformOrigin = null,
             GradientSpreadMethod spreadMethod = GradientSpreadMethod.Pad,
             RelativePoint? center = null,
             RelativePoint? gradientOrigin = null,
             double radius = 0.5)
-            : base(gradientStops, opacity, transform, spreadMethod)
+            : base(gradientStops, opacity, transform, transformOrigin, spreadMethod)
         {
             Center = center ?? RelativePoint.Center;
             GradientOrigin = gradientOrigin ?? RelativePoint.Center;

src/Avalonia.Base/Media/Immutable/ImmutableSolidColorBrush.cs

@@ -53,6 +53,11 @@ namespace Avalonia.Media.Immutable
         /// </summary>
         public ITransform? Transform { get; }
 
+        /// <summary>
+        /// Gets the transform origin of the brush
+        /// </summary>
+        public RelativePoint TransformOrigin { get; }
+
         public bool Equals(ImmutableSolidColorBrush? other)
         {
             if (ReferenceEquals(null, other)) return false;

src/Avalonia.Base/Media/Immutable/ImmutableTileBrush.cs

@@ -15,6 +15,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="destinationRect">The rectangle on the destination in which to paint a tile.</param>
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="transform">The transform of the brush.</param>
+        /// <param name="transformOrigin">The transform origin of the brush</param>
         /// <param name="sourceRect">The rectangle of the source image that will be displayed.</param>
         /// <param name="stretch">
         /// How the source rectangle will be stretched to fill the destination rect.
@@ -27,6 +28,7 @@ namespace Avalonia.Media.Immutable
             RelativeRect destinationRect,
             double opacity,
             ImmutableTransform? transform,
+            RelativePoint transformOrigin,
             RelativeRect sourceRect,
             Stretch stretch,
             TileMode tileMode,
@@ -37,6 +39,7 @@ namespace Avalonia.Media.Immutable
             DestinationRect = destinationRect;
             Opacity = opacity;
             Transform = transform;
+            TransformOrigin = transformOrigin;
             SourceRect = sourceRect;
             Stretch = stretch;
             TileMode = tileMode;
@@ -54,6 +57,7 @@ namespace Avalonia.Media.Immutable
                   source.DestinationRect,
                   source.Opacity,
                   source.Transform?.ToImmutable(),
+                  source.TransformOrigin,
                   source.SourceRect,
                   source.Stretch,
                   source.TileMode,
@@ -78,6 +82,11 @@ namespace Avalonia.Media.Immutable
         /// </summary>
         public ITransform? Transform { get; }
 
+        /// <summary>
+        /// Gets the transform origin of the brush
+        /// </summary>
+        public RelativePoint TransformOrigin { get; }
+
         /// <inheritdoc/>
         public RelativeRect SourceRect { get; }
 

src/Avalonia.Base/Media/Immutable/ImmutableVisualBrush.cs

@@ -17,6 +17,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="destinationRect">The rectangle on the destination in which to paint a tile.</param>
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="transform">The transform of the brush.</param>
+        /// <param name="transformOrigin">The transform origin of the brush</param>
         /// <param name="sourceRect">The rectangle of the source image that will be displayed.</param>
         /// <param name="stretch">
         /// How the source rectangle will be stretched to fill the destination rect.
@@ -30,6 +31,7 @@ namespace Avalonia.Media.Immutable
             RelativeRect? destinationRect = null,
             double opacity = 1,
             ImmutableTransform? transform = null,
+            RelativePoint transformOrigin = new RelativePoint(),
             RelativeRect? sourceRect = null,
             Stretch stretch = Stretch.Uniform,
             TileMode tileMode = TileMode.None,
@@ -40,6 +42,7 @@ namespace Avalonia.Media.Immutable
                   destinationRect ?? RelativeRect.Fill,
                   opacity,
                   transform,
+                  transformOrigin,
                   sourceRect ?? RelativeRect.Fill,
                   stretch,
                   tileMode,

src/Skia/Avalonia.Skia/DrawingContextImpl.cs

@@ -181,7 +181,8 @@ namespace Avalonia.Skia
             var size = geometry.Bounds.Size;
 
             using (var fill = brush != null ? CreatePaint(_fillPaint, brush, size) : default(PaintWrapper))
-            using (var stroke = pen?.Brush != null ? CreatePaint(_strokePaint, pen, size) : default(PaintWrapper))
+            using (var stroke = pen?.Brush != null ? CreatePaint(_strokePaint, pen, 
+                size.Inflate(new Thickness(pen?.Thickness / 2 ?? 0))) : default(PaintWrapper))
             {
                 if (fill.Paint != null)
                 {
@@ -398,7 +399,7 @@ namespace Avalonia.Skia
 
             if (pen?.Brush != null)
             {
-                using (var paint = CreatePaint(_strokePaint, pen, rect.Rect.Size))
+                using (var paint = CreatePaint(_strokePaint, pen, rect.Rect.Size.Inflate(new Thickness(pen?.Thickness / 2 ?? 0))))
                 {
                     if (paint.Paint is object)
                     {
@@ -433,7 +434,7 @@ namespace Avalonia.Skia
 
             if (pen?.Brush != null)
             {
-                using (var paint = CreatePaint(_strokePaint, pen, rect.Size))
+                using (var paint = CreatePaint(_strokePaint, pen, rect.Size.Inflate(new Thickness(pen?.Thickness / 2 ?? 0))))
                 {
                     if (paint.Paint is object)
                     {
@@ -625,8 +626,12 @@ namespace Avalonia.Skia
                     }
                     else
                     {
+                        var transformOrigin = linearGradient.TransformOrigin.ToPixels(targetSize);
+                        var offset = Matrix.CreateTranslation(transformOrigin);
+                        var transform = (-offset) * linearGradient.Transform.Value * (offset);
+
                         using (var shader =
-                            SKShader.CreateLinearGradient(start, end, stopColors, stopOffsets, tileMode, linearGradient.Transform.Value.ToSKMatrix()))
+                            SKShader.CreateLinearGradient(start, end, stopColors, stopOffsets, tileMode, transform.ToSKMatrix()))
                         {
                             paintWrapper.Paint.Shader = shader;
                         }   
@@ -654,8 +659,12 @@ namespace Avalonia.Skia
                         }
                         else
                         {
+                            var transformOrigin = radialGradient.TransformOrigin.ToPixels(targetSize);
+                            var offset = Matrix.CreateTranslation(transformOrigin);
+                            var transform = (-offset) * radialGradient.Transform.Value * (offset);
+                        
                             using (var shader =
-                                SKShader.CreateRadialGradient(center, radius, stopColors, stopOffsets, tileMode, radialGradient.Transform.Value.ToSKMatrix()))
+                                SKShader.CreateRadialGradient(center, radius, stopColors, stopOffsets, tileMode, transform.ToSKMatrix()))
                             {
                                 paintWrapper.Paint.Shader = shader;
                             }
@@ -694,9 +703,14 @@ namespace Avalonia.Skia
                         }
                         else
                         {
+                                
+                            var transformOrigin = radialGradient.TransformOrigin.ToPixels(targetSize);
+                            var offset = Matrix.CreateTranslation(transformOrigin);
+                            var transform = (-offset) * radialGradient.Transform.Value * (offset);
+                           
                             using (var shader = SKShader.CreateCompose(
                                 SKShader.CreateColor(reversedColors[0]),
-                                SKShader.CreateTwoPointConicalGradient(center, radius, origin, 0, reversedColors, reversedStops, tileMode, radialGradient.Transform.Value.ToSKMatrix())
+                                SKShader.CreateTwoPointConicalGradient(center, radius, origin, 0, reversedColors, reversedStops, tileMode, transform.ToSKMatrix())
                             ))
                             {
                                 paintWrapper.Paint.Shader = shader;
@@ -717,7 +731,12 @@ namespace Avalonia.Skia
 
                     if (conicGradient.Transform is { })
                     {
-                        rotation = rotation.PreConcat(conicGradient.Transform.Value.ToSKMatrix());
+                            
+                        var transformOrigin = conicGradient.TransformOrigin.ToPixels(targetSize);
+                        var offset = Matrix.CreateTranslation(transformOrigin);
+                        var transform = (-offset) * conicGradient.Transform.Value * (offset);
+
+                        rotation = rotation.PreConcat(transform.ToSKMatrix());
                     }
 
                     using (var shader = 
@@ -794,7 +813,11 @@ namespace Avalonia.Skia
 
             if (tileBrush.Transform is { })
             {
-                paintTransform = paintTransform.PreConcat(tileBrush.Transform.Value.ToSKMatrix());
+                var origin = tileBrush.TransformOrigin.ToPixels(targetSize);
+                var offset = Matrix.CreateTranslation(origin);
+                var transform = (-offset) * tileBrush.Transform.Value * (offset);
+
+                paintTransform = paintTransform.PreConcat(transform.ToSKMatrix());
             }
 
             using (var shader = image.ToShader(tileX, tileY, paintTransform))