From 749a7312d7899890b2dfedf635af4b03ddb1aa44 Mon Sep 17 00:00:00 2001
From: 2dust <31833384+2dust@users.noreply.github.com>
Date: Tue, 3 Nov 2026 20:47:33 +0800
Subject: [PATCH] Prevent duplicate UI style injections

---
 .../ViewModels/ThemeSettingViewModel.cs       | 65 +++++++++++++------
 1 file changed, 44 insertions(+), 21 deletions(-)

diff --git a/v2rayN/v2rayN.Desktop/ViewModels/ThemeSettingViewModel.cs b/v2rayN/v2rayN.Desktop/ViewModels/ThemeSettingViewModel.cs
index 5fd7f5b2..991b365c 100644
--- a/v2rayN/v2rayN.Desktop/ViewModels/ThemeSettingViewModel.cs
+++ b/v2rayN/v2rayN.Desktop/ViewModels/ThemeSettingViewModel.cs
@@ -7,6 +7,10 @@ namespace v2rayN.Desktop.ViewModels;
 
 public partial class ThemeSettingViewModel : MyReactiveObject
 {
+    private Style? _fontSizeStyle;
+    private Style? _fontSizeExStyle;
+    private Style? _fontFamilyStyle;
+
     [Reactive] public partial string CurrentTheme { get; set; }
 
     [Reactive] public partial int CurrentFontSize { get; set; }
@@ -34,7 +38,7 @@ public partial class ThemeSettingViewModel : MyReactiveObject
         CurrentFontSize = _config.UiItem.CurrentFontSize;
         CurrentLanguage = _config.UiItem.CurrentLanguage;
 
-        this.WhenAnyValue(x => x.CurrentTheme)
+        this.WhenAnyValueUnsafe(x => x.CurrentTheme)
             .Where(y => y.IsNotEmpty())
             .SubscribeAsync(async _ =>
             {
@@ -46,7 +50,7 @@ public partial class ThemeSettingViewModel : MyReactiveObject
                 }
             });
 
-        this.WhenAnyValue(x => x.CurrentFontSize)
+        this.WhenAnyValueUnsafe(x => x.CurrentFontSize)
             .Where(y => y > 0)
             .SubscribeAsync(async _ =>
             {
@@ -58,7 +62,7 @@ public partial class ThemeSettingViewModel : MyReactiveObject
                 }
             });
 
-        this.WhenAnyValue(x => x.CurrentLanguage)
+        this.WhenAnyValueUnsafe(x => x.CurrentLanguage)
             .Where(y => !y.IsNullOrEmpty())
             .SubscribeAsync(async _ =>
             {
@@ -75,19 +79,20 @@ public partial class ThemeSettingViewModel : MyReactiveObject
     private void ModifyTheme()
     {
         var app = Application.Current;
-        if (app is not null)
+        if (app is null)
         {
-            app.RequestedThemeVariant = CurrentTheme switch
-            {
-                nameof(ETheme.Dark) => ThemeVariant.Dark,
-                nameof(ETheme.Light) => ThemeVariant.Light,
-                nameof(ETheme.Aquatic) => SemiTheme.Aquatic,
-                nameof(ETheme.Desert) => SemiTheme.Desert,
-                nameof(ETheme.Dusk) => SemiTheme.Dusk,
-                nameof(ETheme.NightSky) => SemiTheme.NightSky,
-                _ => ThemeVariant.Default,
-            };
+            return;
         }
+        app.RequestedThemeVariant = CurrentTheme switch
+        {
+            nameof(ETheme.Dark) => ThemeVariant.Dark,
+            nameof(ETheme.Light) => ThemeVariant.Light,
+            nameof(ETheme.Aquatic) => SemiTheme.Aquatic,
+            nameof(ETheme.Desert) => SemiTheme.Desert,
+            nameof(ETheme.Dusk) => SemiTheme.Dusk,
+            nameof(ETheme.NightSky) => SemiTheme.NightSky,
+            _ => ThemeVariant.Default,
+        };
     }
 
     private void ModifyFontSize()
@@ -98,7 +103,7 @@ public partial class ThemeSettingViewModel : MyReactiveObject
             return;
         }
 
-        Style style = new(x => Selectors.Or(
+        var style = new Style(x => Selectors.Or(
             x.OfType<Button>(),
             x.OfType<TextBox>(),
             x.OfType<TextBlock>(),
@@ -110,12 +115,12 @@ public partial class ThemeSettingViewModel : MyReactiveObject
             x.OfType<HeaderedContentControl>(),
             x.OfType<TextEditor>()
         ));
-        style.Add(new Setter()
+        style.Add(new Setter
         {
             Property = TemplatedControl.FontSizeProperty,
             Value = size,
         });
-        Application.Current?.Styles.Add(style);
+        ReplaceStyle(ref _fontSizeStyle, style);
 
         ModifyFontSizeEx(size);
     }
@@ -124,9 +129,10 @@ public partial class ThemeSettingViewModel : MyReactiveObject
     {
         //DataGrid
         var rowHeight = 20 + (size / 2);
+
         var style = new Style(x => x.OfType<DataGrid>());
         style.Add(new Setter(DataGrid.RowHeightProperty, rowHeight));
-        Application.Current?.Styles.Add(style);
+        ReplaceStyle(ref _fontSizeExStyle, style);
     }
 
     private void ModifyFontFamily()
@@ -139,7 +145,7 @@ public partial class ThemeSettingViewModel : MyReactiveObject
 
         try
         {
-            Style style = new(x => Selectors.Or(
+            var style = new Style(x => Selectors.Or(
                 x.OfType<Button>(),
                 x.OfType<TextBox>(),
                 x.OfType<TextBlock>(),
@@ -152,16 +158,33 @@ public partial class ThemeSettingViewModel : MyReactiveObject
                 x.OfType<WindowNotificationManager>(),
                 x.OfType<TextEditor>()
             ));
-            style.Add(new Setter()
+            style.Add(new Setter
             {
                 Property = TemplatedControl.FontFamilyProperty,
                 Value = new FontFamily(currentFontFamily),
             });
-            Application.Current?.Styles.Add(style);
+            ReplaceStyle(ref _fontFamilyStyle, style);
         }
         catch (Exception ex)
         {
             Logging.SaveLog("ModifyFontFamily", ex);
         }
     }
+
+    private static void ReplaceStyle(ref Style? oldStyle, Style newStyle)
+    {
+        var app = Application.Current;
+        if (app is null)
+        {
+            return;
+        }
+
+        if (oldStyle is not null)
+        {
+            app.Styles.Remove(oldStyle);
+        }
+
+        oldStyle = newStyle;
+        app.Styles.Add(newStyle);
+    }
 }