Merge pull request #7810 from danielmayost/feature/flowDirectionImpl

Implement FlowDirection - Bidirectional layout

samples/ControlCatalog/MainView.xaml

@@ -190,6 +190,14 @@
                 <WindowTransparencyLevel>Mica</WindowTransparencyLevel>
               </ComboBox.Items>
             </ComboBox>
+            <ComboBox x:Name="FlowDirection"
+                      HorizontalAlignment="Stretch"
+                      SelectedIndex="0">
+              <ComboBox.Items>
+                <FlowDirection>LeftToRight</FlowDirection>
+                <FlowDirection>RightToLeft</FlowDirection>
+              </ComboBox.Items>
+            </ComboBox>
             <ComboBox HorizontalAlignment="Stretch"
                       Items="{Binding WindowStates}"
                       SelectedItem="{Binding WindowState}" />

samples/ControlCatalog/MainView.xaml.cs

@@ -76,6 +76,15 @@ namespace ControlCatalog
                 }
             };
 
+            var flowDirections = this.Find<ComboBox>("FlowDirection");
+            flowDirections.SelectionChanged += (sender, e) =>
+            {
+                if (flowDirections.SelectedItem is FlowDirection flowDirection)
+                {
+                    this.FlowDirection = flowDirection;
+                }
+            };
+
             var decorations = this.Find<ComboBox>("Decorations");
             decorations.SelectionChanged += (sender, e) =>
             {

samples/ControlCatalog/Pages/ScreenPage.cs

@@ -13,6 +13,8 @@ namespace ControlCatalog.Pages
     {
         private double _leftMost;
 
+        protected override bool BypassFlowDirectionPolicies => true;
+
         protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
         {
             base.OnAttachedToVisualTree(e);

src/Avalonia.Controls/ComboBox.cs

@@ -184,6 +184,25 @@ namespace Avalonia.Controls
             this.UpdateSelectionBoxItem(SelectedItem);
         }
 
+        // Because the SelectedItem isn't connected to the visual tree
+        public override void InvalidateMirrorTransform()
+        {
+            base.InvalidateMirrorTransform();
+
+            if (SelectedItem is Control selectedControl)
+            {
+                selectedControl.InvalidateMirrorTransform();
+
+                foreach (var visual in selectedControl.GetVisualDescendants())
+                {
+                    if (visual is Control childControl)
+                    {
+                        childControl.InvalidateMirrorTransform();
+                    }
+                }
+            }
+        }
+
         /// <inheritdoc/>
         protected override void OnKeyDown(KeyEventArgs e)
         {

src/Avalonia.Controls/Control.cs

@@ -160,6 +160,16 @@ namespace Avalonia.Controls
         /// <inheritdoc/>
         bool IDataTemplateHost.IsDataTemplatesInitialized => _dataTemplates != null;
 
+        /// <summary>
+        /// Gets a value indicating whether control bypass FlowDirecton policies.
+        /// </summary>
+        /// <remarks>
+        /// Related to FlowDirection system and returns false as default, so if 
+        /// <see cref="FlowDirection"/> is RTL then control will get a mirror presentation. 
+        /// For controls that want to avoid this behavior, override this property and return true.
+        /// </remarks>
+        protected virtual bool BypassFlowDirectionPolicies => false;
+
         /// <inheritdoc/>
         void ISetterValue.Initialize(ISetter setter)
         {
@@ -219,6 +229,14 @@ namespace Avalonia.Controls
             base.OnDetachedFromVisualTreeCore(e);
         }
 
+        /// <inheritdoc/>
+        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTree(e);
+
+            InvalidateMirrorTransform();
+        }
+
         /// <inheritdoc/>
         protected override void OnGotFocus(GotFocusEventArgs e)
         {
@@ -329,5 +347,55 @@ namespace Avalonia.Controls
                 }
             }
         }
+
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == FlowDirectionProperty)
+            {
+                InvalidateMirrorTransform();
+                
+                foreach (var visual in VisualChildren)
+                {
+                    if (visual is Control child)
+                    {
+                        child.InvalidateMirrorTransform();
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Computes the <see cref="IVisual.HasMirrorTransform"/> value according to the 
+        /// <see cref="FlowDirection"/> and <see cref="BypassFlowDirectionPolicies"/>
+        /// </summary>
+        public virtual void InvalidateMirrorTransform()
+        {
+            var flowDirection = this.FlowDirection;
+            var parentFlowDirection = FlowDirection.LeftToRight;
+
+            bool bypassFlowDirectionPolicies = BypassFlowDirectionPolicies;
+            bool parentBypassFlowDirectionPolicies = false;
+
+            var parent = this.FindAncestorOfType<Control>();
+            if (parent != null)
+            {
+                parentFlowDirection = parent.FlowDirection;
+                parentBypassFlowDirectionPolicies = parent.BypassFlowDirectionPolicies;
+            }
+            else if (Parent is Control logicalParent)
+            {
+                parentFlowDirection = logicalParent.FlowDirection;
+                parentBypassFlowDirectionPolicies = logicalParent.BypassFlowDirectionPolicies;
+            }
+
+            bool thisShouldBeMirrored = flowDirection == FlowDirection.RightToLeft && !bypassFlowDirectionPolicies;
+            bool parentShouldBeMirrored = parentFlowDirection == FlowDirection.RightToLeft && !parentBypassFlowDirectionPolicies;
+
+            bool shouldApplyMirrorTransform = thisShouldBeMirrored != parentShouldBeMirrored;
+
+            HasMirrorTransform = shouldApplyMirrorTransform;
+        }
     }
 }

src/Avalonia.Controls/Image.cs

@@ -66,6 +66,8 @@ namespace Avalonia.Controls
             set { SetValue(StretchDirectionProperty, value); }
         }
 
+        protected override bool BypassFlowDirectionPolicies => true;
+        
         /// <summary>
         /// Renders the control.
         /// </summary>

src/Avalonia.Controls/Presenters/TextPresenter.cs

@@ -282,6 +282,8 @@ namespace Avalonia.Controls.Presenters
             }
         }
 
+        protected override bool BypassFlowDirectionPolicies => true;
+
         /// <summary>
         /// Creates the <see cref="TextLayout"/> used to render the text.
         /// </summary>

src/Avalonia.Controls/Primitives/OverlayPopupHost.cs

@@ -76,7 +76,7 @@ namespace Avalonia.Controls.Primitives
             Rect? rect = null)
         {
             _positionerParameters.ConfigurePosition((TopLevel)_overlayLayer.GetVisualRoot()!, target, placement, offset, anchor,
-                gravity, constraintAdjustment, rect);
+                gravity, constraintAdjustment, rect, FlowDirection);
             UpdatePosition();
         }
 

src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs

@@ -46,6 +46,7 @@ Copyright © 2019 Nikita Tsukanov
 
 using System;
 using Avalonia.VisualTree;
+using Avalonia.Media;
 
 namespace Avalonia.Controls.Primitives.PopupPositioning
 {
@@ -444,7 +445,8 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             TopLevel topLevel,
             IVisual target, PlacementMode placement, Point offset,
             PopupAnchor anchor, PopupGravity gravity,
-            PopupPositionerConstraintAdjustment constraintAdjustment, Rect? rect)
+            PopupPositionerConstraintAdjustment constraintAdjustment, Rect? rect,
+            FlowDirection flowDirection)
         {
             // We need a better way for tracking the last pointer position
 #pragma warning disable CS0618 // Type or member is obsolete
@@ -503,6 +505,32 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
                 else
                     throw new InvalidOperationException("Invalid value for Popup.PlacementMode");
             }
+
+            // Invert coordinate system if FlowDirection is RTL
+            if (flowDirection == FlowDirection.RightToLeft)
+            {
+                if ((positionerParameters.Anchor & PopupAnchor.Right) == PopupAnchor.Right)
+                {
+                    positionerParameters.Anchor ^= PopupAnchor.Right;
+                    positionerParameters.Anchor |= PopupAnchor.Left;
+                }
+                else if ((positionerParameters.Anchor & PopupAnchor.Left) == PopupAnchor.Left)
+                {
+                    positionerParameters.Anchor ^= PopupAnchor.Left;
+                    positionerParameters.Anchor |= PopupAnchor.Right;
+                }
+
+                if ((positionerParameters.Gravity & PopupGravity.Right) == PopupGravity.Right)
+                {
+                    positionerParameters.Gravity ^= PopupGravity.Right;
+                    positionerParameters.Gravity |= PopupGravity.Left;
+                }
+                else if ((positionerParameters.Gravity & PopupGravity.Left) == PopupGravity.Left)
+                {
+                    positionerParameters.Gravity ^= PopupGravity.Left;
+                    positionerParameters.Gravity |= PopupGravity.Right;
+                }
+            }
         }
     }
 

src/Avalonia.Controls/Primitives/PopupRoot.cs

@@ -93,7 +93,7 @@ namespace Avalonia.Controls.Primitives
             Rect? rect = null)
         {
             _positionerParameters.ConfigurePosition(ParentTopLevel, target,
-                placement, offset, anchor, gravity, constraintAdjustment, rect);
+                placement, offset, anchor, gravity, constraintAdjustment, rect, FlowDirection);
 
             if (_positionerParameters.Size != default)
                 UpdatePosition();

src/Avalonia.Controls/TextBlock.cs

@@ -318,6 +318,8 @@ namespace Avalonia.Controls
             set => SetValue(TextDecorationsProperty, value);
         }
         
+        protected override bool BypassFlowDirectionPolicies => true;
+
         /// <summary>
         /// The BaselineOffset property provides an adjustment to baseline offset
         /// </summary>

src/Avalonia.Controls/TopLevel.cs

@@ -350,6 +350,12 @@ namespace Avalonia.Controls
         /// </summary>
         protected virtual ILayoutManager CreateLayoutManager() => new LayoutManager(this);
 
+        public override void InvalidateMirrorTransform()
+        {
+        }
+        
+        protected override bool BypassFlowDirectionPolicies => true;
+        
         /// <summary>
         /// Handles a paint notification from <see cref="ITopLevelImpl.Resized"/>.
         /// </summary>

src/Avalonia.Themes.Default/Controls/CheckBox.xaml

@@ -26,6 +26,7 @@
                     Stretch="Uniform"
                     HorizontalAlignment="Center"
                     VerticalAlignment="Center"
+                    FlowDirection="LeftToRight"
                     Data="M 1145.607177734375,430 C1145.607177734375,430 1141.449951171875,435.0772705078125 1141.449951171875,435.0772705078125 1141.449951171875,435.0772705078125 1139.232177734375,433.0999755859375 1139.232177734375,433.0999755859375 1139.232177734375,433.0999755859375 1138,434.5538330078125 1138,434.5538330078125 1138,434.5538330078125 1141.482177734375,438 1141.482177734375,438 1141.482177734375,438 1141.96875,437.9375 1141.96875,437.9375 1141.96875,437.9375 1147,431.34619140625 1147,431.34619140625 1147,431.34619140625 1145.607177734375,430 1145.607177734375,430 z"/>
               <Rectangle Name="indeterminateMark"
                          Fill="{DynamicResource HighlightBrush}"

src/Avalonia.Themes.Fluent/Controls/CheckBox.xaml

@@ -152,6 +152,7 @@
     <Setter Property="Data" Value="M1507 31L438 1101L-119 543L-29 453L438 919L1417 -59L1507 31Z" />
     <Setter Property="Width" Value="9" />
     <Setter Property="Opacity" Value="1" />
+    <Setter Property="FlowDirection" Value="LeftToRight" />
   </Style>
 
   <!-- Checked PointerOver State -->

src/Avalonia.Visuals/ApiCompatBaseline.txt

@@ -182,5 +182,7 @@ InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Media.TextFo
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Media.GlyphRun Avalonia.Platform.ITextShaperImpl.ShapeText(Avalonia.Utilities.ReadOnlySlice<System.Char>, Avalonia.Media.Typeface, System.Double, System.Globalization.CultureInfo)' is present in the contract but not in the implementation.
 MembersMustExist : Member 'public Avalonia.Media.GlyphRun Avalonia.Platform.ITextShaperImpl.ShapeText(Avalonia.Utilities.ReadOnlySlice<System.Char>, Avalonia.Media.Typeface, System.Double, System.Globalization.CultureInfo)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'protected void Avalonia.Rendering.RendererBase.RenderFps(Avalonia.Platform.IDrawingContextImpl, Avalonia.Rect, System.Nullable<System.Int32>)' does not exist in the implementation but it does exist in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalonia.VisualTree.IVisual.HasMirrorTransform' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalonia.VisualTree.IVisual.HasMirrorTransform.get()' is present in the implementation but not in the contract.
 MembersMustExist : Member 'public void Avalonia.Utilities.ReadOnlySlice<T>..ctor(System.ReadOnlyMemory<T>, System.Int32, System.Int32)' does not exist in the implementation but it does exist in the contract.
-Total Issues: 184
+Total Issues: 186

src/Avalonia.Visuals/Rendering/ImmediateRenderer.cs

@@ -285,6 +285,12 @@ namespace Avalonia.Rendering
                     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;
+                }
+
                 m = renderTransform * m;
 
                 if (clipToBounds)

src/Avalonia.Visuals/Rendering/SceneGraph/SceneBuilder.cs

@@ -195,6 +195,12 @@ namespace Avalonia.Rendering.SceneGraph
                     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;
+                }
+
                 m = renderTransform * m;
 
                 using (contextImpl.BeginUpdate(node))

src/Avalonia.Visuals/Visual.cs

@@ -68,6 +68,12 @@ namespace Avalonia
         public static readonly StyledProperty<IBrush?> OpacityMaskProperty =
             AvaloniaProperty.Register<Visual, IBrush?>(nameof(OpacityMask));
 
+        /// <summary>
+        /// Defines the <see cref="HasMirrorTransform"/> property.
+        /// </summary>
+        public static readonly DirectProperty<Visual, bool> HasMirrorTransformProperty =
+            AvaloniaProperty.RegisterDirect<Visual, bool>(nameof(HasMirrorTransform), o => o.HasMirrorTransform);
+
         /// <summary>
         /// Defines the <see cref="RenderTransform"/> property.
         /// </summary>
@@ -96,6 +102,7 @@ namespace Avalonia
         private TransformedBounds? _transformedBounds;
         private IRenderRoot? _visualRoot;
         private IVisual? _visualParent;
+        private bool _hasMirrorTransform;
 
         /// <summary>
         /// Initializes static members of the <see cref="Visual"/> class.
@@ -107,7 +114,8 @@ namespace Avalonia
                 ClipProperty,
                 ClipToBoundsProperty,
                 IsVisibleProperty,
-                OpacityProperty);
+                OpacityProperty,
+                HasMirrorTransformProperty);
             RenderTransformProperty.Changed.Subscribe(RenderTransformChanged);
             ZIndexProperty.Changed.Subscribe(ZIndexChanged);
         }
@@ -219,6 +227,15 @@ namespace Avalonia
             set { SetValue(OpacityMaskProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether to apply mirror transform on this control.
+        /// </summary>
+        public bool HasMirrorTransform 
+        { 
+            get { return _hasMirrorTransform; }
+            protected set { SetAndRaise(HasMirrorTransformProperty, ref _hasMirrorTransform, value); }
+        }
+
         /// <summary>
         /// Gets or sets the render transform of the control.
         /// </summary>

src/Avalonia.Visuals/VisualExtensions.cs

@@ -110,6 +110,12 @@ namespace Avalonia
                     result *= renderTransform;
                 }
 
+                if (v.HasMirrorTransform)
+                {
+                    var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, v.Bounds.Width, 0);
+                    result *= mirrorMatrix;
+                }
+
                 var topLeft = v.Bounds.TopLeft;
 
                 if (topLeft != default)

src/Avalonia.Visuals/VisualTree/IVisual.cs

@@ -75,6 +75,11 @@ namespace Avalonia.VisualTree
         /// </summary>
         IBrush? OpacityMask { get; set; }
 
+        /// <summary>
+        /// Gets a value indicating whether to apply mirror transform on this control.
+        /// </summary>
+        bool HasMirrorTransform { get; }
+
         /// <summary>
         /// Gets or sets the render transform of the control.
         /// </summary>