From bca06d782868f52e39d06c3c3c8c1d1e3fcb8cae Mon Sep 17 00:00:00 2001
From: Lucas Trzesniewski <lucas.trzesniewski@gmail.com>
Date: Sat, 16 Dec 2023 19:56:20 +0100
Subject: [PATCH] Adjust colors of AvalonEdit built-in highlightings for dark
 themes

---
 ILSpy/TextView/DecompilerTextEditor.cs        |  13 +++
 ILSpy/TextView/DecompilerTextView.xaml        |  55 +++++----
 .../ThemeAwareHighlightingColorizer.cs        | 105 ++++++++++++++++++
 ILSpy/Themes/ThemeManager.cs                  |  15 ++-
 4 files changed, 159 insertions(+), 29 deletions(-)
 create mode 100644 ILSpy/TextView/DecompilerTextEditor.cs
 create mode 100644 ILSpy/TextView/ThemeAwareHighlightingColorizer.cs

diff --git a/ILSpy/TextView/DecompilerTextEditor.cs b/ILSpy/TextView/DecompilerTextEditor.cs
new file mode 100644
index 0000000000..f258794496
--- /dev/null
+++ b/ILSpy/TextView/DecompilerTextEditor.cs
@@ -0,0 +1,13 @@
+using ICSharpCode.AvalonEdit;
+using ICSharpCode.AvalonEdit.Highlighting;
+using ICSharpCode.AvalonEdit.Rendering;
+
+namespace ICSharpCode.ILSpy.TextView;
+
+public class DecompilerTextEditor : TextEditor
+{
+	protected override IVisualLineTransformer CreateColorizer(IHighlightingDefinition highlightingDefinition)
+	{
+		return new ThemeAwareHighlightingColorizer(highlightingDefinition);
+	}
+}
diff --git a/ILSpy/TextView/DecompilerTextView.xaml b/ILSpy/TextView/DecompilerTextView.xaml
index 42786e3968..2230cae602 100644
--- a/ILSpy/TextView/DecompilerTextView.xaml
+++ b/ILSpy/TextView/DecompilerTextView.xaml
@@ -1,17 +1,16 @@
 <UserControl x:Class="ICSharpCode.ILSpy.TextView.DecompilerTextView" x:ClassModifier="public" x:Name="self"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-			 xmlns:properties="clr-namespace:ICSharpCode.ILSpy.Properties"
-			 xmlns:controls="clr-namespace:ICSharpCode.ILSpy.Controls"
-			 xmlns:local="clr-namespace:ICSharpCode.ILSpy.TextView"
-			 xmlns:ae="clr-namespace:ICSharpCode.AvalonEdit;assembly=ICSharpCode.AvalonEdit"
-			 xmlns:editing="clr-namespace:ICSharpCode.AvalonEdit.Editing;assembly=ICSharpCode.AvalonEdit"
-			 xmlns:folding="clr-namespace:ICSharpCode.AvalonEdit.Folding;assembly=ICSharpCode.AvalonEdit"
-			 xmlns:styles="urn:TomsToolbox.Wpf.Styles"
-			 xmlns:themes="clr-namespace:ICSharpCode.ILSpy.Themes">
+             xmlns:properties="clr-namespace:ICSharpCode.ILSpy.Properties"
+             xmlns:controls="clr-namespace:ICSharpCode.ILSpy.Controls"
+             xmlns:local="clr-namespace:ICSharpCode.ILSpy.TextView"
+             xmlns:editing="clr-namespace:ICSharpCode.AvalonEdit.Editing;assembly=ICSharpCode.AvalonEdit"
+             xmlns:folding="clr-namespace:ICSharpCode.AvalonEdit.Folding;assembly=ICSharpCode.AvalonEdit"
+             xmlns:styles="urn:TomsToolbox.Wpf.Styles"
+             xmlns:themes="clr-namespace:ICSharpCode.ILSpy.Themes">
 	<UserControl.Resources>
 		<BooleanToVisibilityConverter x:Key="boolToVisibility" />
-		<SolidColorBrush x:Key="waitAdornerBackgoundBrush" Color="{DynamicResource {x:Static SystemColors.WindowColorKey}}" Opacity=".75"/>
+		<SolidColorBrush x:Key="waitAdornerBackgoundBrush" Color="{DynamicResource {x:Static SystemColors.WindowColorKey}}" Opacity=".75" />
 		<Style TargetType="{x:Type editing:TextArea}">
 			<Setter Property="FocusVisualStyle" Value="{x:Null}" />
 			<Setter Property="SelectionForeground" Value="{x:Null}" />
@@ -31,15 +30,15 @@
 	<Grid>
 		<Border BorderThickness="1,1,0,1" BorderBrush="{DynamicResource {x:Static SystemColors.ControlLightBrushKey}}">
 			<Grid>
-				<ae:TextEditor Name="textEditor" AutomationProperties.Name="Decompilation"  FontFamily="Consolas" FontSize="10pt" IsReadOnly="True"
-				               Background="{DynamicResource {x:Static themes:ResourceKeys.TextBackgroundBrush}}"
-				               Foreground="{DynamicResource {x:Static themes:ResourceKeys.TextForegroundBrush}}"
-				               LineNumbersForeground="{DynamicResource {x:Static themes:ResourceKeys.LineNumbersForegroundBrush}}"
-				               folding:FoldingMargin.FoldingMarkerBackgroundBrush="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"
-				               folding:FoldingMargin.SelectedFoldingMarkerBackgroundBrush="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"
-				               folding:FoldingMargin.FoldingMarkerBrush="{DynamicResource {x:Static SystemColors.ControlDarkBrushKey}}"
-				               folding:FoldingMargin.SelectedFoldingMarkerBrush="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}">
-					<ae:TextEditor.Resources>
+				<local:DecompilerTextEditor x:Name="textEditor" AutomationProperties.Name="Decompilation" FontFamily="Consolas" FontSize="10pt" IsReadOnly="True"
+				                            Background="{DynamicResource {x:Static themes:ResourceKeys.TextBackgroundBrush}}"
+				                            Foreground="{DynamicResource {x:Static themes:ResourceKeys.TextForegroundBrush}}"
+				                            LineNumbersForeground="{DynamicResource {x:Static themes:ResourceKeys.LineNumbersForegroundBrush}}"
+				                            folding:FoldingMargin.FoldingMarkerBackgroundBrush="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"
+				                            folding:FoldingMargin.SelectedFoldingMarkerBackgroundBrush="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"
+				                            folding:FoldingMargin.FoldingMarkerBrush="{DynamicResource {x:Static SystemColors.ControlDarkBrushKey}}"
+				                            folding:FoldingMargin.SelectedFoldingMarkerBrush="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}">
+					<local:DecompilerTextEditor.Resources>
 						<!-- prevent App-wide button style from applying to the buttons in the search box -->
 						<Style TargetType="{x:Type Button}">
 							<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}" />
@@ -65,9 +64,9 @@
 								</Trigger>
 							</Style.Triggers>
 						</Style>
-					</ae:TextEditor.Resources>
-					<ae:TextEditor.Template>
-						<ControlTemplate TargetType="{x:Type ae:TextEditor}">
+					</local:DecompilerTextEditor.Resources>
+					<local:DecompilerTextEditor.Template>
+						<ControlTemplate TargetType="{x:Type local:DecompilerTextEditor}">
 							<controls:ZoomScrollViewer
 								Focusable="False"
 								x:Name="PART_ScrollViewer"
@@ -85,15 +84,15 @@
 								TextOptions.TextFormattingMode="{Binding CurrentZoom, ElementName=PART_ScrollViewer, Converter={x:Static local:ZoomLevelToTextFormattingModeConverter.Instance}}" />
 							<ControlTemplate.Triggers>
 								<Trigger Property="WordWrap"
-									Value="True">
+								         Value="True">
 									<Setter TargetName="PART_ScrollViewer"
-										Property="HorizontalScrollBarVisibility"
-										Value="Disabled" />
+									        Property="HorizontalScrollBarVisibility"
+									        Value="Disabled" />
 								</Trigger>
 							</ControlTemplate.Triggers>
 						</ControlTemplate>
-					</ae:TextEditor.Template>
-				</ae:TextEditor>
+					</local:DecompilerTextEditor.Template>
+				</local:DecompilerTextEditor>
 				<Border Name="waitAdorner" Background="{StaticResource waitAdornerBackgoundBrush}" Visibility="Collapsed">
 					<Grid>
 						<Grid.ColumnDefinitions>
@@ -102,10 +101,10 @@
 							<ColumnDefinition Width="*" />
 						</Grid.ColumnDefinitions>
 						<StackPanel Grid.Column="1" VerticalAlignment="Center">
-							<TextBlock Name="progressTitle" FontSize="14pt" Text="{x:Static properties:Resources.Decompiling}" Margin="3"/>
+							<TextBlock Name="progressTitle" FontSize="14pt" Text="{x:Static properties:Resources.Decompiling}" Margin="3" />
 							<ProgressBar Name="progressBar" Height="16" />
 							<TextBlock Name="progressText" Visibility="Collapsed" Margin="3" />
-							<Button Click="CancelButton_Click" HorizontalAlignment="Center" Margin="3" Content="{x:Static properties:Resources.Cancel}"/>
+							<Button Click="CancelButton_Click" HorizontalAlignment="Center" Margin="3" Content="{x:Static properties:Resources.Cancel}" />
 						</StackPanel>
 					</Grid>
 				</Border>
diff --git a/ILSpy/TextView/ThemeAwareHighlightingColorizer.cs b/ILSpy/TextView/ThemeAwareHighlightingColorizer.cs
new file mode 100644
index 0000000000..8139094826
--- /dev/null
+++ b/ILSpy/TextView/ThemeAwareHighlightingColorizer.cs
@@ -0,0 +1,105 @@
+using System;
+using System.Collections.Generic;
+using System.Windows.Media;
+
+using ICSharpCode.AvalonEdit.Highlighting;
+using ICSharpCode.AvalonEdit.Rendering;
+using ICSharpCode.ILSpy.Themes;
+
+namespace ICSharpCode.ILSpy.TextView;
+
+#nullable enable
+
+public class ThemeAwareHighlightingColorizer : HighlightingColorizer
+{
+	private readonly Dictionary<HighlightingColor, HighlightingColor> _darkColors = new();
+	private readonly bool _isHighlightingThemeAware;
+
+	public ThemeAwareHighlightingColorizer(IHighlightingDefinition highlightingDefinition)
+		: base(highlightingDefinition)
+	{
+		_isHighlightingThemeAware = ThemeManager.Current.IsThemeAware(highlightingDefinition);
+	}
+
+	protected override void ApplyColorToElement(VisualLineElement element, HighlightingColor color)
+	{
+		if (!_isHighlightingThemeAware && ThemeManager.Current.IsDarkTheme)
+		{
+			color = GetColorForDarkTheme(color);
+		}
+
+		base.ApplyColorToElement(element, color);
+	}
+
+	private HighlightingColor GetColorForDarkTheme(HighlightingColor lightColor)
+	{
+		if (lightColor.Foreground is null && lightColor.Background is null)
+		{
+			return lightColor;
+		}
+
+		if (!_darkColors.TryGetValue(lightColor, out var darkColor))
+		{
+			darkColor = lightColor.Clone();
+			darkColor.Foreground = AdjustForDarkTheme(darkColor.Foreground);
+			darkColor.Background = AdjustForDarkTheme(darkColor.Background);
+
+			_darkColors[lightColor] = darkColor;
+		}
+
+		return darkColor;
+	}
+
+	private static HighlightingBrush? AdjustForDarkTheme(HighlightingBrush? lightBrush)
+	{
+		if (lightBrush is SimpleHighlightingBrush simpleBrush && simpleBrush.GetBrush(null) is SolidColorBrush brush)
+		{
+			return new SimpleHighlightingBrush(AdjustForDarkTheme(brush.Color));
+		}
+
+		return lightBrush;
+	}
+
+	private static Color AdjustForDarkTheme(Color color)
+	{
+		var c = System.Drawing.Color.FromArgb(color.R, color.G, color.B);
+		var (h, s, l) = (c.GetHue(), c.GetSaturation(), c.GetBrightness());
+
+		// Invert the lightness, but also increase it a bit
+		l = 1f - MathF.Pow(l, 1.2f);
+
+		// Desaturate the colors, as they'd be too intense otherwise
+		if (s > 0.75f && l < 0.75f)
+		{
+			s *= 0.75f;
+			l *= 1.2f;
+		}
+
+		var (r, g, b) = HslToRgb(h, s, l);
+		return Color.FromArgb(color.A, r, g, b);
+	}
+
+	private static (byte r, byte g, byte b) HslToRgb(float h, float s, float l)
+	{
+		// https://en.wikipedia.org/wiki/HSL_and_HSV#HSL_to_RGB
+
+		var c = (1f - Math.Abs(2f * l - 1f)) * s;
+		h = h % 360f / 60f;
+		var x = c * (1f - Math.Abs(h % 2f - 1f));
+
+		var (r1, g1, b1) = (int)Math.Floor(h) switch {
+			0 => (c, x, 0f),
+			1 => (x, c, 0f),
+			2 => (0f, c, x),
+			3 => (0f, x, c),
+			4 => (x, 0f, c),
+			_ => (c, 0f, x)
+		};
+
+		var m = l - c / 2f;
+		var r = (byte)((r1 + m) * 255f);
+		var g = (byte)((g1 + m) * 255f);
+		var b = (byte)((b1 + m) * 255f);
+		return (r, g, b);
+	}
+}
diff --git a/ILSpy/Themes/ThemeManager.cs b/ILSpy/Themes/ThemeManager.cs
index 97c3a57f54..d0210a2846 100644
--- a/ILSpy/Themes/ThemeManager.cs
+++ b/ILSpy/Themes/ThemeManager.cs
@@ -19,11 +19,11 @@
 #nullable enable
 
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Media;
 
 using ICSharpCode.AvalonEdit.Highlighting;
 
@@ -31,6 +31,8 @@ namespace ICSharpCode.ILSpy.Themes
 {
 	public class ThemeManager
 	{
+		private const string _isThemeAwareKey = "ILSpy.IsThemeAware";
+
 		private string? _theme;
 		private readonly ResourceDictionary _themeDictionaryContainer = new();
 		private readonly Dictionary<string, SyntaxColor> _syntaxColors = new();
@@ -44,6 +46,8 @@ private ThemeManager()
 
 		public string DefaultTheme => "Light";
 
+		public bool IsDarkTheme { get; private set; }
+
 		public static IReadOnlyCollection<string> AllThemes => new[] {
 			"Light",
 			"Dark",
@@ -89,6 +93,13 @@ public void ApplyHighlightingColors(IHighlightingDefinition highlightingDefiniti
 				if (color is not null)
 					syntaxColor.ApplyTo(color);
 			}
+
+			highlightingDefinition.Properties[_isThemeAwareKey] = bool.TrueString;
+		}
+
+		public bool IsThemeAware(IHighlightingDefinition highlightingDefinition)
+		{
+			return highlightingDefinition.Properties.TryGetValue(_isThemeAwareKey, out var value) && value == bool.TrueString;
 		}
 
 		private void UpdateTheme(string? themeName)
@@ -109,6 +120,8 @@ private void UpdateTheme(string? themeName)
 			var resourceDictionary = new ResourceDictionary { Source = new Uri($"/themes/Theme.{themeFileName}.xaml", UriKind.Relative) };
 			_themeDictionaryContainer.MergedDictionaries.Add(resourceDictionary);
 
+			IsDarkTheme = resourceDictionary[ResourceKeys.TextBackgroundBrush] is SolidColorBrush { Color: { R: < 128, G: < 128, B: < 128 } };
+
 			// Iterate over keys first, because we don't want to instantiate all values eagerly, if we don't need them.
 			foreach (var item in resourceDictionary.Keys)
 			{