MarkdownTextBlock: Allows passing an existing MarkdownDocument as the content, closes CommunityToolkit#596

Author: Juan Osorio

Diff for: components/MarkdownTextBlock/samples/MarkdownTextBlockCustomSample.xaml

@@ -1,4 +1,4 @@
-<!--  Licensed to the .NET Foundation under one or more agreements. The .NET Foundation licenses this file to you under the MIT license. See the LICENSE file in the project root for more information.  -->
+<!--  Licensed to the .NET Foundation under one or more agreements. The .NET Foundation licenses this file to you under the MIT license. See the LICENSE file in the project root for more information.  -->
 <Page x:Class="MarkdownTextBlockExperiment.Samples.MarkdownTextBlockCustomSample"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
@@ -39,6 +39,6 @@
                    Text="Built-in Sample" />
         <controls:MarkdownTextBlock Grid.Row="3"
                                     Config="{x:Bind MarkdownConfig, Mode=OneTime}"
-                                    Text="{x:Bind Text, Mode=OneTime}" />
+                                    MarkdownDocument="{x:Bind Doc, Mode=OneTime}" />
     </Grid>
 </Page>

Diff for: components/MarkdownTextBlock/samples/MarkdownTextBlockCustomSample.xaml.cs

@@ -3,6 +3,8 @@
 // See the LICENSE file in the project root for more information.
 
 using CommunityToolkit.Labs.WinUI.MarkdownTextBlock;
+using Markdig;
+using Markdig.Syntax;
 
 namespace MarkdownTextBlockExperiment.Samples;
 
@@ -14,7 +16,7 @@ public sealed partial class MarkdownTextBlockCustomSample : Page
 {
     private MarkdownConfig _config;
     private MarkdownConfig _liveConfig;
-    private string _text;
+    private MarkdownDocument _doc;
     private const string _markdown = @"
 This control was originally written by [Nero Cui](https://github.com/nerocui) for [JitHub](https://github.com/JitHubApp/JitHubV2). The control is powered by the popular [Markdig](https://github.com/xoofx/markdig) markdown parsing library and *almost* supports the full markdown syntax, with a focus on super-efficient parsing and rendering.
 
@@ -594,18 +596,18 @@ public MarkdownConfig LiveMarkdownConfig
         set => _liveConfig = value;
     }
 
-    public string Text
+    public MarkdownDocument Doc
     {
-        get => _text;
-        set => _text = value;
+        get => _doc;
+        set => _doc = value;
     }
 
     public MarkdownTextBlockCustomSample()
     {
         this.InitializeComponent();
         _config = new MarkdownConfig();
         _liveConfig = new MarkdownConfig();
-        _text = _markdown;
+        _doc = Markdown.Parse(_markdown);
         MarkdownTextBox.Text = "# Hello World\n\n";
     }
 }

Diff for: components/MarkdownTextBlock/src/MarkdownTextBlock.xaml.cs

@@ -5,6 +5,7 @@
 using CommunityToolkit.Labs.WinUI.MarkdownTextBlock.Renderers;
 using CommunityToolkit.Labs.WinUI.MarkdownTextBlock.TextElements;
 using Markdig;
+using Markdig.Syntax;
 
 namespace CommunityToolkit.Labs.WinUI.MarkdownTextBlock;
 
@@ -30,6 +31,12 @@ public partial class MarkdownTextBlock : Control
         typeof(MarkdownTextBlock),
         new PropertyMetadata(null, OnTextChanged));
 
+    private static readonly DependencyProperty MarkdownDocumentProperty = DependencyProperty.Register(
+        nameof(MarkdownDocument),
+        typeof(MarkdownDocument),
+        typeof(MarkdownTextBlock),
+        new PropertyMetadata(null, OnMarkdownDocumentChanged));
+
     public MarkdownConfig Config
     {
         get => (MarkdownConfig)GetValue(ConfigProperty);
@@ -42,6 +49,12 @@ public string Text
         set => SetValue(TextProperty, value);
     }
 
+    public MarkdownDocument? MarkdownDocument
+    {
+        get => (MarkdownDocument?)GetValue(MarkdownDocumentProperty);
+        set => SetValue(MarkdownDocumentProperty, value);
+    }
+
     private static void OnConfigChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
     {
         if (d is MarkdownTextBlock self && e.NewValue != null)
@@ -51,6 +64,14 @@ private static void OnConfigChanged(DependencyObject d, DependencyPropertyChange
     }
 
     private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        if (d is MarkdownTextBlock self && e.NewValue != null)
+        {
+            self.MarkdownDocument = string.IsNullOrEmpty(self.Text) ? null : Markdown.Parse(self.Text, self._pipeline);
+        }
+    }
+
+    private static void OnMarkdownDocumentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
     {
         if (d is MarkdownTextBlock self && e.NewValue != null)
         {
@@ -96,10 +117,9 @@ private void ApplyText(bool rerender)
                 _renderer.ReloadDocument();
             }
 
-            if (!string.IsNullOrEmpty(Text))
+            if (MarkdownDocument != null)
             {
-                var markdown = Markdown.Parse(Text, _pipeline);
-                _renderer.Render(markdown);
+                _renderer.Render(MarkdownDocument);
             }
         }
     }