From 0dd57be793916b752bceeec7fcb173b40746c2be Mon Sep 17 00:00:00 2001
From: EaZy <eazy4d@gmail.com>
Date: Mon, 22 Jun 2026 12:41:10 +0100
Subject: [PATCH 1/2] Better Dark Mode & Image Viewer Toggle Fixes

Overview
This pull request introduces improved dark mode support by adding a tri-state theme cycle option to the tray menu, and fixes an issue with the Image Viewer background toggle affecting the global application theme.

Changes:
1. Global Theme Tray Cycle: Added AppTheme option in SettingHelper and SetTheme method in App.xaml.cs; added tray menu item in TrayIconManager.cs to cycle Auto/Light/Dark with dynamic label.
2. Image Viewer Background Toggle Fix: Decoupled Image Viewer canvas background from global Theme; added CanvasTheme property and saved LastCanvasTheme; updated bindings in ImagePanel.xaml.

Files modified: QuickLook/App.xaml.cs; QuickLook/TrayIconManager.cs; QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs; QuickLook.Plugin.ImageViewer/ImagePanel.xaml

How to test: Run QuickLook, use tray menu to cycle theme, open image and toggle background; canvas background should change without affecting global UI.
---
 .../ImagePanel.xaml                           |  6 +++---
 .../ImagePanel.xaml.cs                        | 18 +++++++++++++---
 QuickLook/App.xaml.cs                         | 21 +++++++++++++++++--
 QuickLook/TrayIconManager.cs                  | 14 +++++++++++++
 4 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml
index e177a8509..fedc4a78c 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml
+++ b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml
@@ -1,4 +1,4 @@
-<UserControl x:Class="QuickLook.Plugin.ImageViewer.ImagePanel"
+<UserControl x:Class="QuickLook.Plugin.ImageViewer.ImagePanel"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:animatedImage="clr-namespace:QuickLook.Plugin.ImageViewer.AnimatedImage"
@@ -24,7 +24,7 @@
             <Rectangle.Style>
                 <Style>
                     <Style.Triggers>
-                        <DataTrigger Binding="{Binding ElementName=imagePanel, Path=Theme}" Value="{x:Static plugin:Themes.Dark}">
+                        <DataTrigger Binding="{Binding ElementName=imagePanel, Path=CanvasTheme}" Value="{x:Static plugin:Themes.Dark}">
                             <Setter Property="Rectangle.Fill">
                                 <Setter.Value>
                                     <ImageBrush AlignmentY="Top"
@@ -38,7 +38,7 @@
                                 </Setter.Value>
                             </Setter>
                         </DataTrigger>
-                        <DataTrigger Binding="{Binding ElementName=imagePanel, Path=Theme}" Value="{x:Static plugin:Themes.Light}">
+                        <DataTrigger Binding="{Binding ElementName=imagePanel, Path=CanvasTheme}" Value="{x:Static plugin:Themes.Light}">
                             <Setter Property="Rectangle.Fill">
                                 <Setter.Value>
                                     <ImageBrush AlignmentY="Top"
diff --git a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
index dbda7e2a2..b9e31d735 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
@@ -1,4 +1,4 @@
-// Copyright © 2017-2026 QL-Win Contributors
+// Copyright © 2017-2026 QL-Win Contributors
 //
 // This file is part of QuickLook program.
 //
@@ -107,6 +107,7 @@ internal ImagePanel(ContextObject context, MetaProvider meta) : this()
 
         ShowMeta();
         Theme = ContextObject.Theme;
+        CanvasTheme = (Themes)SettingHelper.Get("LastCanvasTheme", (int)Theme, "QuickLook.Plugin.ImageViewer");
     }
 
     public bool ZoomWithControlKey
@@ -140,6 +141,17 @@ public Themes Theme
         }
     }
 
+    private Themes _canvasTheme = Themes.Dark;
+    public Themes CanvasTheme
+    {
+        get => _canvasTheme;
+        set
+        {
+            _canvasTheme = value;
+            OnPropertyChanged();
+        }
+    }
+
     public BitmapScalingMode RenderMode
     {
         get => _renderMode;
@@ -381,9 +393,9 @@ private void OnReverseColorOnClick(object sender, RoutedEventArgs e)
 
     private void OnBackgroundColourOnClick(object sender, RoutedEventArgs e)
     {
-        Theme = Theme == Themes.Dark ? Themes.Light : Themes.Dark;
+        CanvasTheme = CanvasTheme == Themes.Dark ? Themes.Light : Themes.Dark;
 
-        SettingHelper.Set("LastTheme", (int)Theme, "QuickLook.Plugin.ImageViewer");
+        SettingHelper.Set("LastCanvasTheme", (int)CanvasTheme, "QuickLook.Plugin.ImageViewer");
     }
 
     private void ShowMeta()
diff --git a/QuickLook/App.xaml.cs b/QuickLook/App.xaml.cs
index 9184585ff..0f32a3fbe 100644
--- a/QuickLook/App.xaml.cs
+++ b/QuickLook/App.xaml.cs
@@ -227,8 +227,9 @@ protected override void OnStartup(StartupEventArgs e)
         // Therefore, the time-consuming initialization code can't be placed before `OnStartup`
         base.OnStartup(e);
 
-        // Set initial theme based on system settings
-        ThemeManager.Apply(OSThemeHelper.AppsUseDarkTheme() ? ApplicationTheme.Dark : ApplicationTheme.Light);
+        // Set initial theme based on system or user settings
+        var appTheme = SettingHelper.Get("AppTheme", 0, "QuickLook");
+        SetTheme(appTheme);
 
         // Initialize MessageBox patching
         MessageBoxPatcher.Initialize();
@@ -346,4 +347,20 @@ private void RunListener(StartupEventArgs e)
         KeystrokeDispatcher.GetInstance();
         PipeServerManager.GetInstance();
     }
+
+    public static void SetTheme(int theme)
+    {
+        switch (theme)
+        {
+            case 1:
+                ThemeManager.Apply(ApplicationTheme.Light);
+                break;
+            case 2:
+                ThemeManager.Apply(ApplicationTheme.Dark);
+                break;
+            default:
+                ThemeManager.Apply(OSThemeHelper.AppsUseDarkTheme() ? ApplicationTheme.Dark : ApplicationTheme.Light);
+                break;
+        }
+    }
 }
diff --git a/QuickLook/TrayIconManager.cs b/QuickLook/TrayIconManager.cs
index ab831c930..f3ad9e42a 100644
--- a/QuickLook/TrayIconManager.cs
+++ b/QuickLook/TrayIconManager.cs
@@ -38,6 +38,7 @@ internal partial class TrayIconManager : IDisposable
 
     private readonly TrayMenuItem _itemAutorun = null!;
     private readonly TrayMenuItem _itemCloseOnLostFocus = null!;
+    private readonly TrayMenuItem _itemThemeCycle = null!;
 
     private TrayIconManager()
     {
@@ -70,6 +71,17 @@ private TrayIconManager()
                     Header = TranslationHelper.Get("Icon_OpenDataFolder"),
                     Command = new RelayCommand(() => Process.Start("explorer.exe", SettingHelper.LocalDataPath)),
                 },
+                _itemThemeCycle = new TrayMenuItem()
+                {
+                    Header = "Theme: Auto",
+                    Command = new RelayCommand(() =>
+                    {
+                        var current = SettingHelper.Get("AppTheme", 0, "QuickLook");
+                        var next = (current + 1) % 3;
+                        SettingHelper.Set("AppTheme", next, "QuickLook");
+                        App.SetTheme(next);
+                    }),
+                },
                 _itemAutorun = new TrayMenuItem()
                 {
                     Header = TranslationHelper.Get("Icon_RunAtStartup"),
@@ -109,6 +121,8 @@ private TrayIconManager()
         {
             _itemAutorun.IsChecked = AutoStartupHelper.IsAutorun();
             _itemCloseOnLostFocus.IsChecked = SettingHelper.Get("CloseOnLostFocus", false);
+            var theme = SettingHelper.Get("AppTheme", 0, "QuickLook");
+            _itemThemeCycle.Header = theme == 1 ? "Theme: Light" : theme == 2 ? "Theme: Dark" : "Theme: Auto";
         };
     }
 

From b97260641f55c6103373cf8cf2de26636b684265 Mon Sep 17 00:00:00 2001
From: EaZy <eazy4d@gmail.com>
Date: Mon, 22 Jun 2026 13:25:27 +0100
Subject: [PATCH 2/2] Refine dark mode and theme cycling implementation

- Added strongly-typed AppThemeMode enum (Auto, Light, Dark) to replace magic integers
- Created centralized setting keys (KeyAppTheme, KeyLastCanvasTheme) in SettingHelper for type-safe access
- Wired tray menu text through TranslationHelper for full localization support with English fallbacks
- Updated all theme and canvas theme references to use enum and constants throughout App.xaml.cs, TrayIconManager.cs, and ImagePanel.xaml.cs
- Improved code clarity and maintainability by eliminating raw string literals and magic numbers
---
 QuickLook.Common/Helpers/SettingHelper.cs       |  5 ++++-
 .../ImagePanel.xaml.cs                          |  4 ++--
 QuickLook/App.xaml.cs                           | 17 ++++++++++++-----
 QuickLook/TrayIconManager.cs                    | 14 ++++++++------
 4 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/QuickLook.Common/Helpers/SettingHelper.cs b/QuickLook.Common/Helpers/SettingHelper.cs
index 10c3e4d46..71f31d092 100644
--- a/QuickLook.Common/Helpers/SettingHelper.cs
+++ b/QuickLook.Common/Helpers/SettingHelper.cs
@@ -1,4 +1,4 @@
-// Copyright © 2017-2026 QL-Win Contributors
+// Copyright © 2017-2026 QL-Win Contributors
 //
 // This file is part of QuickLook program.
 //
@@ -26,6 +26,9 @@ namespace QuickLook.Common.Helpers;
 
 public static class SettingHelper
 {
+    public const string KeyAppTheme = "AppTheme";
+    public const string KeyLastCanvasTheme = "LastCanvasTheme";
+
     public static readonly string LocalDataPath =
         IsPortableVersion()
             ? Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) ?? string.Empty,
diff --git a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
index b9e31d735..fe2d13d14 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
@@ -107,7 +107,7 @@ internal ImagePanel(ContextObject context, MetaProvider meta) : this()
 
         ShowMeta();
         Theme = ContextObject.Theme;
-        CanvasTheme = (Themes)SettingHelper.Get("LastCanvasTheme", (int)Theme, "QuickLook.Plugin.ImageViewer");
+        CanvasTheme = (Themes)SettingHelper.Get(SettingHelper.KeyLastCanvasTheme, (int)Theme, "QuickLook.Plugin.ImageViewer");
     }
 
     public bool ZoomWithControlKey
@@ -395,7 +395,7 @@ private void OnBackgroundColourOnClick(object sender, RoutedEventArgs e)
     {
         CanvasTheme = CanvasTheme == Themes.Dark ? Themes.Light : Themes.Dark;
 
-        SettingHelper.Set("LastCanvasTheme", (int)CanvasTheme, "QuickLook.Plugin.ImageViewer");
+        SettingHelper.Set(SettingHelper.KeyLastCanvasTheme, (int)CanvasTheme, "QuickLook.Plugin.ImageViewer");
     }
 
     private void ShowMeta()
diff --git a/QuickLook/App.xaml.cs b/QuickLook/App.xaml.cs
index 0f32a3fbe..d2f09ac84 100644
--- a/QuickLook/App.xaml.cs
+++ b/QuickLook/App.xaml.cs
@@ -35,6 +35,13 @@
 
 namespace QuickLook;
 
+public enum AppThemeMode
+{
+    Auto = 0,
+    Light = 1,
+    Dark = 2
+}
+
 public partial class App : Application
 {
     public static readonly string LocalDataPath = SettingHelper.LocalDataPath;
@@ -228,8 +235,8 @@ protected override void OnStartup(StartupEventArgs e)
         base.OnStartup(e);
 
         // Set initial theme based on system or user settings
-        var appTheme = SettingHelper.Get("AppTheme", 0, "QuickLook");
-        SetTheme(appTheme);
+        var appTheme = SettingHelper.Get(SettingHelper.KeyAppTheme, (int)AppThemeMode.Auto, "QuickLook");
+        SetTheme((AppThemeMode)appTheme);
 
         // Initialize MessageBox patching
         MessageBoxPatcher.Initialize();
@@ -348,14 +355,14 @@ private void RunListener(StartupEventArgs e)
         PipeServerManager.GetInstance();
     }
 
-    public static void SetTheme(int theme)
+    public static void SetTheme(AppThemeMode theme)
     {
         switch (theme)
         {
-            case 1:
+            case AppThemeMode.Light:
                 ThemeManager.Apply(ApplicationTheme.Light);
                 break;
-            case 2:
+            case AppThemeMode.Dark:
                 ThemeManager.Apply(ApplicationTheme.Dark);
                 break;
             default:
diff --git a/QuickLook/TrayIconManager.cs b/QuickLook/TrayIconManager.cs
index f3ad9e42a..79bc64b7c 100644
--- a/QuickLook/TrayIconManager.cs
+++ b/QuickLook/TrayIconManager.cs
@@ -73,12 +73,12 @@ private TrayIconManager()
                 },
                 _itemThemeCycle = new TrayMenuItem()
                 {
-                    Header = "Theme: Auto",
+                    Header = TranslationHelper.Get("Icon_ThemeAuto", failsafe: "Theme: Auto"),
                     Command = new RelayCommand(() =>
                     {
-                        var current = SettingHelper.Get("AppTheme", 0, "QuickLook");
-                        var next = (current + 1) % 3;
-                        SettingHelper.Set("AppTheme", next, "QuickLook");
+                        var current = SettingHelper.Get(SettingHelper.KeyAppTheme, (int)AppThemeMode.Auto, "QuickLook");
+                        var next = (AppThemeMode)((current + 1) % 3);
+                        SettingHelper.Set(SettingHelper.KeyAppTheme, (int)next, "QuickLook");
                         App.SetTheme(next);
                     }),
                 },
@@ -121,8 +121,10 @@ private TrayIconManager()
         {
             _itemAutorun.IsChecked = AutoStartupHelper.IsAutorun();
             _itemCloseOnLostFocus.IsChecked = SettingHelper.Get("CloseOnLostFocus", false);
-            var theme = SettingHelper.Get("AppTheme", 0, "QuickLook");
-            _itemThemeCycle.Header = theme == 1 ? "Theme: Light" : theme == 2 ? "Theme: Dark" : "Theme: Auto";
+            var theme = (AppThemeMode)SettingHelper.Get(SettingHelper.KeyAppTheme, (int)AppThemeMode.Auto, "QuickLook");
+            _itemThemeCycle.Header = theme == AppThemeMode.Light ? TranslationHelper.Get("Icon_ThemeLight", failsafe: "Theme: Light") :
+                                     theme == AppThemeMode.Dark ? TranslationHelper.Get("Icon_ThemeDark", failsafe: "Theme: Dark") :
+                                     TranslationHelper.Get("Icon_ThemeAuto", failsafe: "Theme: Auto");
         };
     }