Fixes #5008. Fix Markdown codeblock background attribute

Examples/UICatalog/Scenarios/Deepdives.cs

@@ -58,10 +58,7 @@ public override void Main ()
             Height = Dim.Fill (1)
         };
 
-        _markdownView = new Markdown
-        {
-            Width = Dim.Fill (), Height = Dim.Fill (), SyntaxHighlighter = new TextMateSyntaxHighlighter (ThemeName.Abbys), UseThemeBackground = true
-        };
+        _markdownView = new Markdown { Width = Dim.Fill (), Height = Dim.Fill (), SyntaxHighlighter = new TextMateSyntaxHighlighter () };
 
         _markdownView.ViewportSettings |= ViewportSettingsFlags.HasHorizontalScrollBar;
 
@@ -114,7 +111,13 @@ public override void Main ()
 
         Shortcut contentWidthShortcut = new () { CommandView = _contentWidthUpDown, Text = "Content Width" };
 
-        DropDownList<ThemeName> themeDropDown = new () { ReadOnly = true, CanFocus = false, Value = ThemeName.Abbys, Autocomplete = null };
+        DropDownList<ThemeName> themeDropDown = new ()
+        {
+            ReadOnly = true,
+            CanFocus = false,
+            Value = (Enum.TryParse (_markdownView.SyntaxHighlighter.ThemeName, out ThemeName theme) ? theme : ThemeName.DarkPlus),
+            Autocomplete = null
+        };
 
         themeDropDown.ValueChanged += (_, e) =>
                                       {
@@ -123,18 +126,25 @@ public override void Main ()
                                               return;
                                           }
 
-                                          TextMateSyntaxHighlighter highlighter = new (themeName);
-                                          _markdownView.SyntaxHighlighter = highlighter;
-
-                                          // Force re-layout so code blocks pick up new theme
-                                          string text = _markdownView.Text;
-                                          _markdownView.Text = string.Empty;
-                                          _markdownView.Text = text;
+                                          _markdownView.SyntaxHighlighter = new TextMateSyntaxHighlighter (themeName);
                                       };
 
         Shortcut themeShortcut = new () { Text = "_Theme:", CommandView = themeDropDown, MouseHighlightStates = MouseState.None };
 
-        CheckBox themeBgCheckBox = new () { Text = "Theme _BG", Value = CheckState.UnChecked };
+        // Auto-select a light or dark syntax theme based on the terminal's actual background color.
+        _app.Driver!.DefaultAttributeChanged += (_, e) =>
+                                                 {
+                                                     if (_markdownView is null || e.NewValue is not { } attr)
+                                                     {
+                                                         return;
+                                                     }
+
+                                                     ThemeName autoTheme = TextMateSyntaxHighlighter.GetThemeForBackground (attr.Background);
+                                                     _markdownView.SyntaxHighlighter = new TextMateSyntaxHighlighter (autoTheme);
+                                                     themeDropDown.Value = autoTheme;
+                                                 };
+
+        CheckBox themeBgCheckBox = new () { Text = "Theme _BG", Value = _markdownView.UseThemeBackground ? CheckState.Checked : CheckState.UnChecked };
 
         themeBgCheckBox.ValueChanged += (_, e) =>
                                         {
@@ -144,11 +154,6 @@ public override void Main ()
                                             }
 
                                             _markdownView.UseThemeBackground = e.NewValue == CheckState.Checked;
-
-                                            // Force re-layout
-                                            string text = _markdownView.Text;
-                                            _markdownView.Text = string.Empty;
-                                            _markdownView.Text = text;
                                         };
 
         Shortcut themeBgShortcut = new () { CommandView = themeBgCheckBox };

Examples/UICatalog/Scenarios/MarkdownTester.cs

@@ -14,7 +14,14 @@ public override void Main ()
         using IApplication app = Application.Create ();
         app.Init ();
 
-        Window window = new () { Title = "Markdown Tester", Width = Dim.Fill (), Height = Dim.Fill (), BorderStyle = LineStyle.None };
+        Window window = new ()
+        {
+            Title = "Markdown Tester",
+            Width = Dim.Fill (),
+            Height = Dim.Fill (),
+            BorderStyle = LineStyle.None,
+            SchemeName = SchemeManager.SchemesToSchemeName (Schemes.Accent)
+        };
 
         // --- Source editor (top half) ---
         FrameView editorFrame = new ()
@@ -58,9 +65,7 @@ public override void Main ()
             Y = 0,
             Width = Dim.Fill (),
             Height = Dim.Fill (),
-            Text = Markdown.DefaultMarkdownSample,
-            SyntaxHighlighter = new TextMateSyntaxHighlighter (),
-            UseThemeBackground = true
+            SyntaxHighlighter = new TextMateSyntaxHighlighter ()
         };
 
         previewFrame.Add (preview);
@@ -74,33 +79,49 @@ public override void Main ()
 
         Shortcut quitShortcut = new () { Title = "Quit", Key = Key.Esc, Action = app.RequestStop };
 
-        DropDownList<ThemeName> themeDropDown = new () { Value = ThemeName.DarkPlus, ReadOnly = true, CanFocus = false };
+        DropDownList<ThemeName> themeDropDown = new ()
+        {
+            Value = (preview.SyntaxHighlighter as TextMateSyntaxHighlighter)?.ThemeName ?? ThemeName.DarkPlus,
+            ReadOnly = true,
+            CanFocus = false
+        };
 
         themeDropDown.ValueChanged += (_, e) =>
                                       {
-                                          if (e.Value is { } themeName)
+                                          if (e.Value is not { } themeName)
                                           {
-                                              TextMateSyntaxHighlighter highlighter = new (themeName);
-                                              preview.SyntaxHighlighter = highlighter;
-                                              preview.Text = editor.Text;
+                                              return;
                                           }
+                                          preview.SyntaxHighlighter = new TextMateSyntaxHighlighter (themeName);
+                                          preview.Text = editor.Text;
                                       };
 
         Shortcut themeShortcut = new () { Title = "Theme", CommandView = themeDropDown };
 
-        CheckBox themeBgCheckBox = new () { Text = "Theme _BG", Value = CheckState.UnChecked };
+        // Auto-select a light or dark syntax theme based on the terminal's actual background color.
+        app.Driver!.DefaultAttributeChanged += (_, e) =>
+                                                {
+                                                    if (e.NewValue is not { } attr)
+                                                    {
+                                                        return;
+                                                    }
+
+                                                    ThemeName autoTheme = TextMateSyntaxHighlighter.GetThemeForBackground (attr.Background);
+                                                    preview.SyntaxHighlighter = new TextMateSyntaxHighlighter (autoTheme);
+                                                    themeDropDown.Value = autoTheme;
+                                                };
 
-        themeBgCheckBox.ValueChanged += (_, e) =>
-                                        {
-                                            preview.UseThemeBackground = e.NewValue == CheckState.Checked;
-                                            preview.Text = editor.Text;
-                                        };
+        CheckBox themeBgCheckBox = new () { Text = "Theme _BG", Value = preview.UseThemeBackground ? CheckState.Checked : CheckState.UnChecked };
+
+        themeBgCheckBox.ValueChanged += (_, e) => { preview.UseThemeBackground = e.NewValue == CheckState.Checked; };
 
         Shortcut themeBgShortcut = new () { CommandView = themeBgCheckBox };
 
         statusBar.Add (themeShortcut, themeBgShortcut, quitShortcut);
         window.Add (statusBar);
 
+        preview.Text = editor.Text;
+
         app.Run (window);
         window.Dispose ();
     }

Examples/mdv/Program.cs

@@ -209,8 +209,7 @@ static void RunFullScreen (List<string> files, ThemeName syntaxTheme)
     {
         Width = Dim.Fill (),
         Height = Dim.Fill (1), // leave room for StatusBar
-        SyntaxHighlighter = new TextMateSyntaxHighlighter (syntaxTheme),
-        UseThemeBackground = true
+        SyntaxHighlighter = new TextMateSyntaxHighlighter (syntaxTheme)
     };
 
     // Vertical scrollbar is already enabled by MarkdownView constructor
@@ -295,26 +294,30 @@ static void RunFullScreen (List<string> files, ThemeName syntaxTheme)
                                           return;
                                       }
 
-                                      TextMateSyntaxHighlighter highlighter = new (themeName);
-                                      markdownView.SyntaxHighlighter = highlighter;
-
-                                      string text = markdownView.Text;
-                                      markdownView.Text = string.Empty;
-                                      markdownView.Text = text;
+                                      markdownView.SyntaxHighlighter = new TextMateSyntaxHighlighter (themeName);
                                   };
 
     statusItems.Add (new Shortcut { Title = "Theme", CommandView = themeDropDown });
 
+    // Auto-select a light or dark syntax theme based on the terminal's actual background color.
+    app.Driver!.DefaultAttributeChanged += (_, e) =>
+                                            {
+                                                if (e.NewValue is not { } attr)
+                                                {
+                                                    return;
+                                                }
+
+                                                ThemeName autoTheme = TextMateSyntaxHighlighter.GetThemeForBackground (attr.Background);
+                                                markdownView.SyntaxHighlighter = new TextMateSyntaxHighlighter (autoTheme);
+                                                themeDropDown.Value = autoTheme;
+                                            };
+
     // Theme background toggle
     CheckBox themeBgCheckBox = new () { Text = "Theme _BG", Value = CheckState.Checked };
 
     themeBgCheckBox.ValueChanged += (_, e) =>
                                     {
                                         markdownView.UseThemeBackground = e.NewValue == CheckState.Checked;
-
-                                        string text = markdownView.Text;
-                                        markdownView.Text = string.Empty;
-                                        markdownView.Text = text;
                                     };
 
     statusItems.Add (new Shortcut { CommandView = themeBgCheckBox });

GitVersion.yml

@@ -18,7 +18,7 @@
 # - develop: Develop branch for V2
 #
 # Package Naming:
-# - from develop: 2.1.0-develop.1 (minor version increments)
+# - from develop: 2.0.0-develop.1 (patch version increments)
 # - from main (pre-release): 2.0.0-prealpha.1 or 2.0.0-beta.1
 # - from main (release): 2.0.0 (patch version increments)
 #
@@ -46,8 +46,8 @@ branches:
     regex: develop
     # Adds 'develop' as pre-release label (e.g., 2.1.0-develop.1)
     label: develop
-    # Increments minor version (x.y+1.z) on commits
-    increment: Minor
+    # Increments patch version (x.y.z+1) on commits
+    increment: Patch
     # No source branches specified as this is the root of development
     source-branches: []
     # Indicates this branch feeds into release branches

Terminal.Gui/Drawing/Markdown/ISyntaxHighlighter.cs

@@ -22,6 +22,11 @@ public interface ISyntaxHighlighter
     /// </summary>
     void ResetState ();
 
+    /// <summary>
+    ///     Gets the name of the currently active syntax highlighting theme.
+    /// </summary>
+    string ThemeName { get; }
+
     /// <summary>
     ///     Gets the default background color from the active syntax highlighting theme.
     ///     Used by code block views to fill their viewport background consistently with

Terminal.Gui/Drawing/Markdown/MarkdownAttributeHelper.cs

@@ -30,7 +30,11 @@ public static Attribute GetAttributeForSegment (View view, StyledSegment segment
     {
         if (segment.Attribute is { } explicitAttr)
         {
-            return explicitAttr;
+            // When a caller-provided background override is present, apply it even to
+            // segments that carry an explicit attribute from the highlighter. This keeps
+            // the token foreground colours but ensures the background matches the fill
+            // colour of the containing code block / viewport.
+            return themeBackground is { } overrideBg ? explicitAttr with { Background = overrideBg } : explicitAttr;
         }
 
         // Use the provided theme background, or fall back to the view's normal background.

Terminal.Gui/Drawing/Markdown/TextMateSyntaxHighlighter.cs

@@ -62,7 +62,7 @@ public class TextMateSyntaxHighlighter : ISyntaxHighlighter
     /// </param>
     public TextMateSyntaxHighlighter (ThemeName theme = ThemeName.DarkPlus)
     {
-        CurrentThemeName = theme;
+        ThemeName = theme;
         _registryOptions = new RegistryOptions (theme);
         _registry = new Registry (_registryOptions);
         CacheThemeDefaults ();
@@ -138,8 +138,11 @@ public IReadOnlyList<StyledSegment> Highlight (string code, string? language)
     /// <returns>A theme appropriate for the background luminance.</returns>
     public static ThemeName GetThemeForBackground (Color background) => background.IsDarkColor () ? ThemeName.DarkPlus : ThemeName.LightPlus;
 
-    /// <summary>Gets the <see cref="ThemeName"/> that is currently active.</summary>
-    public ThemeName CurrentThemeName { get; private set; }
+    /// <summary>Gets the <see cref="TextMateSharp.Grammars.ThemeName"/> that is currently active.</summary>
+    public ThemeName ThemeName { get; private set; }
+
+    /// <inheritdoc/>
+    string ISyntaxHighlighter.ThemeName => ThemeName.ToString ();
 
     /// <inheritdoc/>
     public Color? DefaultBackground => _defaultBackground;
@@ -188,7 +191,7 @@ public IReadOnlyList<StyledSegment> Highlight (string code, string? language)
     /// <param name="theme">The new VS Code theme to use.</param>
     public void SetTheme (ThemeName theme)
     {
-        CurrentThemeName = theme;
+        ThemeName = theme;
         _registryOptions = new RegistryOptions (theme);
         _registry = new Registry (_registryOptions);
         _grammarCache.Clear ();

Terminal.Gui/Drivers/DriverImpl.cs

@@ -279,10 +279,18 @@ private void OnSizeMonitorOnSizeChanged (object? _, SizeChangedEventArgs e) =>
     /// <inheritdoc/>
     public Attribute? DefaultAttribute { get; private set; }
 
+    /// <inheritdoc/>
+    public event EventHandler<ValueChangedEventArgs<Attribute?>>? DefaultAttributeChanged;
+
     /// <summary>
     ///     Sets the terminal's default attribute (queried via OSC 10/11).
     /// </summary>
-    internal void SetDefaultAttribute (Attribute attr) => DefaultAttribute = attr;
+    internal void SetDefaultAttribute (Attribute attr)
+    {
+        Attribute? old = DefaultAttribute;
+        DefaultAttribute = attr;
+        DefaultAttributeChanged?.Invoke (this, new ValueChangedEventArgs<Attribute?> (old, attr));
+    }
 
     /// <inheritdoc/>
     public TerminalColorCapabilities? ColorCapabilities { get; private set; }

Terminal.Gui/Drivers/IDriver.cs

@@ -150,6 +150,11 @@ public interface IDriver : IDisposable
     /// </summary>
     Attribute? DefaultAttribute { get; }
 
+    /// <summary>
+    ///     Raised when <see cref="DefaultAttribute"/> changes (e.g. after terminal color detection completes).
+    /// </summary>
+    event EventHandler<ValueChangedEventArgs<Attribute?>>? DefaultAttributeChanged;
+
     /// <summary>
     ///     Gets the terminal's color capabilities as detected from environment variables.
     ///     <see langword="null"/> if detection has not been performed.

Terminal.Gui/Views/Markdown/Markdown.cs

@@ -76,15 +76,41 @@ public MarkdownPipeline? MarkdownPipeline
 
     /// <summary>Gets or sets an optional syntax highlighter for fenced code blocks.</summary>
     /// <value>An <see cref="ISyntaxHighlighter"/> implementation, or <see langword="null"/> for plain-text code blocks.</value>
-    public ISyntaxHighlighter? SyntaxHighlighter { get; set; }
+    public ISyntaxHighlighter? SyntaxHighlighter
+    {
+        get;
+        set
+        {
+            if (ReferenceEquals (field, value))
+            {
+                return;
+            }
+
+            field = value;
+            InvalidateParsedAndLayout ();
+        }
+    }
 
     /// <summary>
     ///     Gets or sets whether the view fills its background with the syntax highlighting theme's
     ///     editor background color. When <see langword="true"/> and a <see cref="SyntaxHighlighter"/>
     ///     is set, the theme's <see cref="ISyntaxHighlighter.DefaultBackground"/> is used for the
-    ///     entire viewport, headings, body text, and table cells. Defaults to <see langword="false"/>.
+    ///     entire viewport, headings, body text, and table cells. Defaults to <see langword="true"/>.
     /// </summary>
-    public bool UseThemeBackground { get; set; }
+    public bool UseThemeBackground
+    {
+        get;
+        set
+        {
+            if (field == value)
+            {
+                return;
+            }
+
+            field = value;
+            InvalidateParsedAndLayout ();
+        }
+    } = true;
 
     /// <summary>
     ///     Gets or sets whether heading lines include the <c>#</c> prefix (e.g. <c># </c>, <c>## </c>).

Terminal.Gui/Views/Markdown/MarkdownCodeBlock.cs

@@ -284,7 +284,7 @@ protected override bool OnDrawingContent (DrawContext? context)
 
             foreach (StyledSegment segment in segments)
             {
-                Attribute attr = MarkdownAttributeHelper.GetAttributeForSegment (this, segment, SyntaxHighlighter);
+                Attribute attr = MarkdownAttributeHelper.GetAttributeForSegment (this, segment, SyntaxHighlighter, codeBg);
                 SetAttribute (attr);
 
                 foreach (string grapheme in GraphemeHelper.GetGraphemes (segment.Text))