Port WPF's FormattedText to Avalonia and rework TextPresenter

samples/ControlCatalog/Pages/ScreenPage.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Globalization;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
@@ -49,25 +50,33 @@ public override void Render(DrawingContext context)
                     context.DrawRectangle(p, boundsRect);
                     context.DrawRectangle(p, workingAreaRect);
 
-                    var text = new FormattedText() { Typeface = new Typeface("Arial"), FontSize = 18 };
 
-                    text.Text = $"Bounds: {screen.Bounds.TopLeft} {screen.Bounds.Width}:{screen.Bounds.Height}";
-                    context.DrawText(drawBrush, boundsRect.Position.WithY(boundsRect.Size.Height), text);
-
-                    text.Text = $"WorkArea: {screen.WorkingArea.TopLeft} {screen.WorkingArea.Width}:{screen.WorkingArea.Height}";
-                    context.DrawText(drawBrush, boundsRect.Position.WithY(boundsRect.Size.Height + 20), text);
+                    var formattedText = CreateFormattedText($"Bounds: {screen.Bounds.Width}:{screen.Bounds.Height}");
+                    context.DrawText(formattedText, boundsRect.Position.WithY(boundsRect.Size.Height));
 
-                    text.Text = $"Scaling: {screen.PixelDensity * 100}%";
-                    context.DrawText(drawBrush, boundsRect.Position.WithY(boundsRect.Size.Height + 40), text);
-
-                    text.Text = $"Primary: {screen.Primary}";
-                    context.DrawText(drawBrush, boundsRect.Position.WithY(boundsRect.Size.Height + 60), text);
-
-                    text.Text = $"Current: {screen.Equals(w.Screens.ScreenFromBounds(new PixelRect(w.Position, PixelSize.FromSize(w.Bounds.Size, scaling))))}";
-                    context.DrawText(drawBrush, boundsRect.Position.WithY(boundsRect.Size.Height + 80), text);
+                    formattedText =
+                        CreateFormattedText($"WorkArea: {screen.WorkingArea.Width}:{screen.WorkingArea.Height}");
+                    context.DrawText(formattedText, boundsRect.Position.WithY(boundsRect.Size.Height + 20));
+
+                    formattedText = CreateFormattedText($"Scaling: {screen.PixelDensity * 100}%");
+                    context.DrawText(formattedText, boundsRect.Position.WithY(boundsRect.Size.Height + 40));
+
+                    formattedText = CreateFormattedText($"Primary: {screen.Primary}");
+                    context.DrawText(formattedText, boundsRect.Position.WithY(boundsRect.Size.Height + 60));
+
+                    formattedText =
+                        CreateFormattedText(
+                            $"Current: {screen.Equals(w.Screens.ScreenFromBounds(new PixelRect(w.Position, PixelSize.FromSize(w.Bounds.Size, scaling))))}");
+                    context.DrawText(formattedText, boundsRect.Position.WithY(boundsRect.Size.Height + 80));
                 }
 
             context.DrawRectangle(p, new Rect(w.Position.X / 10f + Math.Abs(_leftMost), w.Position.Y / 10f, w.Bounds.Width / 10, w.Bounds.Height / 10));
         }
+
+        private FormattedText CreateFormattedText(string textToFormat)
+        {
+            return new FormattedText(textToFormat, CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
+                Typeface.Default, 12, Brushes.Green);
+        }
     }
 }

samples/RenderDemo/MainWindow.xaml

@@ -57,6 +57,9 @@
     <TabItem Header="GlyphRun">
       <pages:GlyphRunPage />
     </TabItem>
+    <TabItem Header="FormattedText">
+      <pages:FormattedTextPage />
+    </TabItem>
     <TabItem Header="LineBounds">
       <pages:LineBoundsPage />
     </TabItem>

samples/RenderDemo/Pages/CustomSkiaPage.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using System.Globalization;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Media;
@@ -41,7 +42,10 @@ public void Render(IDrawingContextImpl context)
             {
                 var canvas = (context as ISkiaDrawingContextImpl)?.SkCanvas;
                 if (canvas == null)
-                    context.DrawText(Brushes.Black, new Point(), _noSkia.PlatformImpl);
+                    using (var c = new DrawingContext(context, false))
+                    {
+                        c.DrawText(_noSkia, new Point());
+                    }
                 else
                 {
                     canvas.Save();
@@ -108,10 +112,9 @@ static int Animate(int d, int from, int to)
 
         public override void Render(DrawingContext context)
         {
-            var noSkia = new FormattedText()
-            {
-                Text = "Current rendering API is not Skia"
-            };
+            var noSkia = new FormattedText("Current rendering API is not Skia", CultureInfo.CurrentCulture,
+                FlowDirection.LeftToRight, Typeface.Default, 12, Brushes.Black);
+
             context.Custom(new CustomDrawOp(new Rect(0, 0, Bounds.Width, Bounds.Height), noSkia));
             Dispatcher.UIThread.InvokeAsync(InvalidateVisual, DispatcherPriority.Background);
         }

samples/RenderDemo/Pages/FormattedTextPage.axaml

@@ -0,0 +1,7 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="RenderDemo.Pages.FormattedTextPage">
+</UserControl>

samples/RenderDemo/Pages/FormattedTextPage.axaml.cs

@@ -0,0 +1,60 @@
+using System.Globalization;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using Avalonia.Media;
+
+namespace RenderDemo.Pages
+{
+    public class FormattedTextPage : UserControl
+    {
+        public FormattedTextPage()
+        {
+            this.InitializeComponent();
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+
+        public override void Render(DrawingContext context)
+        {
+            const string testString = "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor";
+
+            // Create the initial formatted text string.
+            var formattedText = new FormattedText(
+                testString,
+                CultureInfo.GetCultureInfo("en-us"),
+                FlowDirection.LeftToRight,
+                new Typeface("Verdana"),
+                32,
+                Brushes.Black) { MaxTextWidth = 300, MaxTextHeight = 240 };
+
+            // Set a maximum width and height. If the text overflows these values, an ellipsis "..." appears.
+
+            // Use a larger font size beginning at the first (zero-based) character and continuing for 5 characters.
+            // The font size is calculated in terms of points -- not as device-independent pixels.
+            formattedText.SetFontSize(36 * (96.0 / 72.0), 0, 5);
+
+            // Use a Bold font weight beginning at the 6th character and continuing for 11 characters.
+            formattedText.SetFontWeight(FontWeight.Bold, 6, 11);
+
+            var gradient = new LinearGradientBrush
+            {
+                GradientStops =
+                    new GradientStops { new GradientStop(Colors.Orange, 0), new GradientStop(Colors.Teal, 1) },
+                StartPoint = new RelativePoint(0,0, RelativeUnit.Relative),
+                EndPoint = new RelativePoint(0,1, RelativeUnit.Relative)
+            };
+
+            // Use a linear gradient brush beginning at the 6th character and continuing for 11 characters.
+            formattedText.SetForegroundBrush(gradient, 6, 11);
+
+            // Use an Italic font style beginning at the 28th character and continuing for 28 characters.
+            formattedText.SetFontStyle(FontStyle.Italic, 28, 28);
+
+            context.DrawText(formattedText, new Point(10, 0));
+        }
+    }
+}

samples/RenderDemo/Pages/GlyphRunPage.xaml.cs

@@ -13,6 +13,7 @@ public class GlyphRunPage : UserControl
         private GlyphTypeface _glyphTypeface = Typeface.Default.GlyphTypeface;
         private readonly Random _rand = new Random();
         private ushort[] _glyphIndices = new ushort[1];
+        private char[] _characters = new char[1];
         private float _fontSize = 20;
         private int _direction = 10;
 
@@ -38,7 +39,7 @@ private void InitializeComponent()
 
         private void UpdateGlyphRun()
         {
-            var c = (uint)_rand.Next(65, 90);
+            var c = (char)_rand.Next(65, 90);
 
             if (_fontSize + _direction > 200)
             {
@@ -54,14 +55,16 @@ private void UpdateGlyphRun()
 
             _glyphIndices[0] = _glyphTypeface.GetGlyph(c);
 
+            _characters[0] = c;
+
             var scale = (double)_fontSize / _glyphTypeface.DesignEmHeight;
 
             var drawingGroup = new DrawingGroup();
 
             var glyphRunDrawing = new GlyphRunDrawing
             {
                 Foreground = Brushes.Black,
-                GlyphRun = new GlyphRun(_glyphTypeface, _fontSize, _glyphIndices),
+                GlyphRun = new GlyphRun(_glyphTypeface, _fontSize, _characters, _glyphIndices)
             };
 
             drawingGroup.Children.Add(glyphRunDrawing);

src/Avalonia.Base/Utilities/ImmutableReadOnlyListStructEnumerator.cs

@@ -3,7 +3,7 @@
 
 namespace Avalonia.Utilities
 {
-    public struct ImmutableReadOnlyListStructEnumerator<T> : IEnumerator, IEnumerator<T>
+    public struct ImmutableReadOnlyListStructEnumerator<T> : IEnumerator<T>
     {
         private readonly IReadOnlyList<T> _readOnlyList;
         private int _pos;

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -43,6 +43,10 @@ MembersMustExist : Member 'public void Avalonia.Controls.Embedding.Offscreen.Off
 MembersMustExist : Member 'public void Avalonia.Controls.Embedding.Offscreen.OffscreenTopLevelImplBase.SetCursor(Avalonia.Platform.IPlatformHandle)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.AvaloniaProperty Avalonia.AvaloniaProperty Avalonia.Controls.Notifications.NotificationCard.CloseOnClickProperty' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.Platform.ITopLevelNativeMenuExporter.SetNativeMenu(Avalonia.Controls.NativeMenu)' is present in the contract but not in the implementation.
+MembersMustExist : Member 'protected Avalonia.Media.FormattedText Avalonia.Controls.Presenters.TextPresenter.CreateFormattedText()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.Media.FormattedText Avalonia.Controls.Presenters.TextPresenter.FormattedText.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Int32 Avalonia.Controls.Presenters.TextPresenter.GetCaretIndex(Avalonia.Point)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected void Avalonia.Controls.Presenters.TextPresenter.InvalidateFormattedText()' does not exist in the implementation but it does exist in the contract.
 CannotRemoveBaseTypeOrInterface : Type 'Avalonia.Controls.Primitives.PopupRoot' does not implement interface 'Avalonia.Utilities.IWeakSubscriber<Avalonia.Controls.ResourcesChangedEventArgs>' in the implementation but it does in the contract.
 EnumValuesMustMatch : Enum value 'Avalonia.Platform.ExtendClientAreaChromeHints Avalonia.Platform.ExtendClientAreaChromeHints.Default' is (System.Int32)2 in the implementation but (System.Int32)1 in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.Nullable<Avalonia.Size> Avalonia.Platform.ITopLevelImpl.FrameSize' is present in the implementation but not in the contract.
@@ -63,4 +67,4 @@ InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platfor
 MembersMustExist : Member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size, Avalonia.Platform.PlatformResizeReason)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.ITrayIconImpl Avalonia.Platform.IWindowingPlatform.CreateTrayIcon()' is present in the implementation but not in the contract.
-Total Issues: 64
+Total Issues: 68

src/Avalonia.Controls/Control.cs

@@ -1,10 +1,12 @@
 using System;
 using System.ComponentModel;
+using System.Runtime.CompilerServices;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
+using Avalonia.Media;
 using Avalonia.Rendering;
 using Avalonia.Styling;
 using Avalonia.VisualTree;
@@ -60,7 +62,13 @@ public class Control : InputElement, IControl, INamed, IVisualBrushInitialize, I
         public static readonly RoutedEvent<ContextRequestedEventArgs> ContextRequestedEvent =
             RoutedEvent.Register<Control, ContextRequestedEventArgs>(nameof(ContextRequested),
                 RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
-
+
+        /// <summary>
+        /// Defines the <see cref="FlowDirection"/> property.
+        /// </summary>
+        public static readonly AttachedProperty<FlowDirection> FlowDirectionProperty =
+            AvaloniaProperty.RegisterAttached<Control, Control, FlowDirection>(nameof(FlowDirection), inherits: true);
+
         private DataTemplates? _dataTemplates;
         private IControl? _focusAdorner;
 
@@ -108,6 +116,15 @@ public object? Tag
             get => GetValue(TagProperty);
             set => SetValue(TagProperty, value);
         }
+
+        /// <summary>
+        /// Gets or sets the text flow direction.
+        /// </summary>
+        public FlowDirection FlowDirection
+        {
+            get => GetValue(FlowDirectionProperty);
+            set => SetValue(FlowDirectionProperty, value);
+        }
 
         /// <summary>
         /// Occurs when the user has completed a context input gesture, such as a right-click.