Benedikt Stebner
4 years ago
6 changed files with 353 additions and 147 deletions
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using System; |
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using System.Collections.Generic; |
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using Avalonia.Controls.Documents; |
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using Avalonia.Media; |
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using Avalonia.Media.TextFormatting; |
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namespace Avalonia.Controls |
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{ |
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/// <summary>
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/// A control that displays a block of text.
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/// </summary>
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public class RichTextBlock : TextBlock, IInlineHost |
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{ |
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/// <summary>
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/// Defines the <see cref="Inlines"/> property.
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/// </summary>
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public static readonly StyledProperty<InlineCollection> InlinesProperty = |
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AvaloniaProperty.Register<RichTextBlock, InlineCollection>( |
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nameof(Inlines)); |
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public RichTextBlock() |
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{ |
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Inlines = new InlineCollection |
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{ |
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Parent = this, |
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InlineHost = this |
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}; |
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} |
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/// <summary>
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/// Gets or sets the inlines.
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/// </summary>
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public InlineCollection Inlines |
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{ |
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get => GetValue(InlinesProperty); |
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set => SetValue(InlinesProperty, value); |
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} |
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public void Add(Inline inline) |
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{ |
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if (Inlines is not null) |
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{ |
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Inlines.Add(inline); |
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} |
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} |
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public new void Add(string text) |
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{ |
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if (Inlines is not null) |
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{ |
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Inlines.Add(text); |
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} |
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} |
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/// <summary>
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/// Creates the <see cref="TextLayout"/> used to render the text.
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/// </summary>
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/// <param name="constraint">The constraint of the text.</param>
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/// <param name="text">The text to format.</param>
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/// <returns>A <see cref="TextLayout"/> object.</returns>
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protected override TextLayout CreateTextLayout(Size constraint, string? text) |
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{ |
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var defaultProperties = new GenericTextRunProperties( |
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new Typeface(FontFamily, FontStyle, FontWeight, FontStretch), |
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FontSize, |
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TextDecorations, |
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Foreground); |
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var paragraphProperties = new GenericTextParagraphProperties(FlowDirection, TextAlignment, true, false, |
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defaultProperties, TextWrapping, LineHeight, 0); |
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ITextSource textSource; |
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var inlines = Inlines; |
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if (inlines is not null && inlines.HasComplexContent) |
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{ |
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var textRuns = new List<TextRun>(); |
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foreach (var inline in inlines) |
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{ |
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inline.BuildTextRun(textRuns); |
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} |
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textSource = new InlinesTextSource(textRuns); |
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} |
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else |
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{ |
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textSource = new SimpleTextSource((text ?? "").AsMemory(), defaultProperties); |
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} |
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return new TextLayout( |
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textSource, |
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paragraphProperties, |
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TextTrimming, |
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constraint.Width, |
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constraint.Height, |
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maxLines: MaxLines, |
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lineHeight: LineHeight); |
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} |
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protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change) |
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{ |
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base.OnPropertyChanged(change); |
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switch (change.Property.Name) |
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{ |
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case nameof(InlinesProperty): |
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{ |
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OnInlinesChanged(change.OldValue as InlineCollection, change.NewValue as InlineCollection); |
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InvalidateTextLayout(); |
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break; |
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} |
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case nameof(TextProperty): |
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{ |
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OnTextChanged(change.OldValue as string, change.NewValue as string); |
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break; |
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} |
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} |
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} |
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private void OnTextChanged(string? oldValue, string? newValue) |
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{ |
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if (oldValue == newValue) |
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{ |
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return; |
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} |
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if (Inlines is null) |
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{ |
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return; |
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} |
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Inlines.Text = newValue; |
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} |
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private void OnInlinesChanged(InlineCollection? oldValue, InlineCollection? newValue) |
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{ |
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if (oldValue is not null) |
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{ |
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oldValue.Parent = null; |
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oldValue.InlineHost = null; |
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oldValue.Invalidated -= (s, e) => InvalidateTextLayout(); |
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} |
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if (newValue is not null) |
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{ |
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newValue.Parent = this; |
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newValue.InlineHost = this; |
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newValue.Invalidated += (s, e) => InvalidateTextLayout(); |
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} |
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} |
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void IInlineHost.AddVisualChild(IControl child) |
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{ |
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if (child.VisualParent == null) |
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{ |
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VisualChildren.Add(child); |
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} |
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} |
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void IInlineHost.Invalidate() |
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{ |
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InvalidateTextLayout(); |
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} |
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private readonly struct InlinesTextSource : ITextSource |
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{ |
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private readonly IReadOnlyList<TextRun> _textRuns; |
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public InlinesTextSource(IReadOnlyList<TextRun> textRuns) |
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{ |
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_textRuns = textRuns; |
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} |
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public TextRun? GetTextRun(int textSourceIndex) |
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{ |
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var currentPosition = 0; |
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foreach (var textRun in _textRuns) |
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{ |
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if (textRun.TextSourceLength == 0) |
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{ |
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continue; |
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} |
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if (currentPosition >= textSourceIndex) |
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{ |
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return textRun; |
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} |
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currentPosition += textRun.TextSourceLength; |
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} |
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return null; |
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} |
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} |
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} |
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} |
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