Merge pull request #204 from reactivemarbles/AddNewControlsToAvaloniaUI

Add RichTextBox control with formatting support

Author: ChrisPulman

src/CrissCross.Avalonia.UI/AssemblyInfo.cs

@@ -0,0 +1,9 @@
+// Copyright (c) 2019-2025 ReactiveUI Association Incorporated. All rights reserved.
+// ReactiveUI Association Incorporated licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+using Avalonia.Metadata;
+
+[assembly: XmlnsDefinition("https://github.com/reactivemarbles/CrissCross.Avalonia.UI", "CrissCross.Avalonia.UI")]
+[assembly: XmlnsDefinition("https://github.com/reactivemarbles/CrissCross.Avalonia.UI", "CrissCross.Avalonia.UI.Controls")]
+[assembly: XmlnsDefinition("https://github.com/reactivemarbles/CrissCross.Avalonia.UI", "CrissCross.Avalonia.UI.Appearance")]

src/CrissCross.Avalonia.UI/Controls/RichTextBox/FormattedTextPresenter.cs

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+// Copyright (c) 2019-2025 ReactiveUI Association Incorporated. All rights reserved.
+// ReactiveUI Association Incorporated licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Documents;
+using Avalonia.Media;
+
+namespace CrissCross.Avalonia.UI.Controls;
+
+/// <summary>
+/// A control that displays formatted text using Inlines.
+/// </summary>
+public class FormattedTextPresenter : SelectableTextBlock
+{
+    /// <summary>
+    /// Property for <see cref="Document"/>.
+    /// </summary>
+    public static readonly StyledProperty<RichTextDocument?> DocumentProperty =
+        AvaloniaProperty.Register<FormattedTextPresenter, RichTextDocument?>(nameof(Document));
+
+    /// <summary>
+    /// Property for <see cref="DefaultForeground"/>.
+    /// </summary>
+    public static readonly StyledProperty<IBrush?> DefaultForegroundProperty =
+        AvaloniaProperty.Register<FormattedTextPresenter, IBrush?>(nameof(DefaultForeground));
+
+    /// <summary>
+    /// Property for <see cref="DefaultFontSize"/>.
+    /// </summary>
+    public static readonly StyledProperty<double> DefaultFontSizeProperty =
+        AvaloniaProperty.Register<FormattedTextPresenter, double>(nameof(DefaultFontSize), 14);
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="FormattedTextPresenter"/> class.
+    /// </summary>
+    public FormattedTextPresenter()
+    {
+        // Enable text selection
+        SelectionBrush = new SolidColorBrush(Color.FromArgb(100, 0, 120, 212));
+    }
+
+    /// <summary>
+    /// Gets or sets the document to display.
+    /// </summary>
+    public RichTextDocument? Document
+    {
+        get => GetValue(DocumentProperty);
+        set => SetValue(DocumentProperty, value);
+    }
+
+    /// <summary>
+    /// Gets or sets the default foreground brush.
+    /// </summary>
+    public IBrush? DefaultForeground
+    {
+        get => GetValue(DefaultForegroundProperty);
+        set => SetValue(DefaultForegroundProperty, value);
+    }
+
+    /// <summary>
+    /// Gets or sets the default font size.
+    /// </summary>
+    public double DefaultFontSize
+    {
+        get => GetValue(DefaultFontSizeProperty);
+        set => SetValue(DefaultFontSizeProperty, value);
+    }
+
+    /// <summary>
+    /// Updates the inline collection from the document.
+    /// </summary>
+    public void UpdateInlines()
+    {
+        Inlines?.Clear();
+
+        if (Document is null || Document.Segments.Count == 0)
+        {
+            return;
+        }
+
+        Inlines ??= [];
+
+        foreach (var segment in Document.Segments)
+        {
+            var run = new Run(segment.Text)
+            {
+                FontWeight = segment.FontWeight,
+                FontStyle = segment.FontStyle,
+            };
+
+            // Apply text decorations
+            if (segment.TextDecorations is { } decorations)
+            {
+                run.TextDecorations = decorations;
+            }
+
+            // Apply custom foreground
+            if (segment.Foreground is not null)
+            {
+                run.Foreground = segment.Foreground;
+            }
+            else if (DefaultForeground is not null)
+            {
+                run.Foreground = DefaultForeground;
+            }
+
+            // Apply custom font size
+            if (segment.FontSize.HasValue)
+            {
+                run.FontSize = segment.FontSize.Value;
+            }
+
+            // Apply custom font family
+            if (segment.FontFamily is not null)
+            {
+                run.FontFamily = segment.FontFamily;
+            }
+
+            Inlines.Add(run);
+        }
+    }
+
+    /// <inheritdoc/>
+    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+    {
+        base.OnPropertyChanged(change);
+
+        if (change is null)
+        {
+            return;
+        }
+
+        if (change.Property == DocumentProperty ||
+            change.Property == DefaultForegroundProperty ||
+            change.Property == DefaultFontSizeProperty ||
+            change.Property == ForegroundProperty ||
+            change.Property == FontSizeProperty ||
+            change.Property == FontFamilyProperty)
+        {
+            UpdateInlines();
+        }
+    }
+}

src/CrissCross.Avalonia.UI/Controls/RichTextBox/FormattingEventArgs.cs

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+// Copyright (c) 2019-2025 ReactiveUI Association Incorporated. All rights reserved.
+// ReactiveUI Association Incorporated licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+using Avalonia.Interactivity;
+
+namespace CrissCross.Avalonia.UI.Controls;
+
+/// <summary>
+/// Event arguments for formatting events.
+/// </summary>
+/// <remarks>
+/// Initializes a new instance of the <see cref="FormattingEventArgs"/> class.
+/// </remarks>
+/// <param name="routedEvent">The routed event.</param>
+/// <param name="source">The source.</param>
+/// <param name="formatType">The type of formatting applied.</param>
+/// <param name="affectedText">The text that was formatted.</param>
+public class FormattingEventArgs(RoutedEvent routedEvent, object source, TextFormatType formatType, string affectedText) : RoutedEventArgs(routedEvent, source)
+{
+    /// <summary>
+    /// Gets the type of formatting that was applied.
+    /// </summary>
+    public TextFormatType FormatType { get; } = formatType;
+
+    /// <summary>
+    /// Gets the text that was formatted.
+    /// </summary>
+    public string AffectedText { get; } = affectedText;
+}