Refactor drop shadow handling for window border style (#4318)

Author: Jack251970

Flow.Launcher.Core/Resource/Theme.cs

@@ -473,76 +473,114 @@ public bool ChangeTheme(string theme = null)
 
         public void AddDropShadowEffectToCurrentTheme()
         {
-            var dict = GetCurrentResourceDictionary();
+            // Get current theme's WindowBorderStyle
+            var theme = _settings.Theme;
+            var dict = GetThemeResourceDictionary(theme);
+            var windowBorderStyle = dict.Contains("WindowBorderStyle") ? dict["WindowBorderStyle"] as Style : null;
+            if (windowBorderStyle == null) return;
 
-            var windowBorderStyle = dict["WindowBorderStyle"] as Style;
+            // Get a new unsealed style based on the old one, and copy Resources and Triggers
+            var newWindowBorderStyle = new Style(typeof(Border));
+            ThemeHelper.CopyStyle(windowBorderStyle, newWindowBorderStyle);
 
-            var effectSetter = new Setter
+            // Identify existing Margin to calculate new Margin, and copy other setters
+            Setter existingMarginSetter = null;
+            foreach (var setterBase in windowBorderStyle.Setters)
             {
-                Property = UIElement.EffectProperty,
-                Value = new DropShadowEffect
+                if (setterBase is Setter setter)
                 {
-                    Opacity = 0.3,
-                    ShadowDepth = 12,
-                    Direction = 270,
-                    BlurRadius = 30
+                    // Skip existing Margin (we'll replace it)
+                    if (setter.Property == FrameworkElement.MarginProperty)
+                    {
+                        existingMarginSetter = setter;
+                        continue;
+                    }
+
+                    // Skip existing Effect (we'll ensure strictly one is added)
+                    if (setter.Property == UIElement.EffectProperty) continue;
                 }
-            };
 
-            if (windowBorderStyle.Setters.FirstOrDefault(setterBase => setterBase is Setter setter && setter.Property == FrameworkElement.MarginProperty) is not Setter marginSetter)
-            {
-                var margin = new Thickness(ShadowExtraMargin, 12, ShadowExtraMargin, ShadowExtraMargin);
-                marginSetter = new Setter()
-                {
-                    Property = FrameworkElement.MarginProperty,
-                    Value = margin,
-                };
-                windowBorderStyle.Setters.Add(marginSetter);
+                // Add other setters (e.g. Background, BorderThickness)
+                newWindowBorderStyle.Setters.Add(setterBase);
+            }
 
-                SetResizeBoarderThickness(margin);
+            // Calculate new Margin
+            Thickness newMargin;
+            if (existingMarginSetter == null)
+            {
+                newMargin = new Thickness(ShadowExtraMargin, 12, ShadowExtraMargin, ShadowExtraMargin);
             }
             else
             {
-                var baseMargin = (Thickness)marginSetter.Value;
-                var newMargin = new Thickness(
+                var baseMargin = (Thickness)existingMarginSetter.Value;
+                newMargin = new Thickness(
                     baseMargin.Left + ShadowExtraMargin,
                     baseMargin.Top + ShadowExtraMargin,
                     baseMargin.Right + ShadowExtraMargin,
                     baseMargin.Bottom + ShadowExtraMargin);
-                marginSetter.Value = newMargin;
-
-                SetResizeBoarderThickness(newMargin);
             }
 
-            windowBorderStyle.Setters.Add(effectSetter);
+            // Add new Margin Setter
+            ThemeHelper.ReplaceSetter(newWindowBorderStyle, new Setter(FrameworkElement.MarginProperty, newMargin));
 
-            UpdateResourceDictionary(dict);
+            // Add Drop Shadow Effect Setter
+            ThemeHelper.ReplaceSetter(newWindowBorderStyle, new Setter
+            {
+                Property = UIElement.EffectProperty,
+                Value = new DropShadowEffect
+                {
+                    Opacity = 0.3,
+                    ShadowDepth = 12,
+                    Direction = 270,
+                    BlurRadius = 30
+                }
+            });
+
+            SetResizeBoarderThickness(newMargin);
+
+            Application.Current.Resources["WindowBorderStyle"] = newWindowBorderStyle;
         }
 
         public void RemoveDropShadowEffectFromCurrentTheme()
         {
-            var dict = GetCurrentResourceDictionary();
-            var windowBorderStyle = dict["WindowBorderStyle"] as Style;
+            // Get current theme's WindowBorderStyle
+            var theme = _settings.Theme;
+            var dict = GetThemeResourceDictionary(theme);
+            var windowBorderStyle = dict.Contains("WindowBorderStyle") ? dict["WindowBorderStyle"] as Style : null;
+            if (windowBorderStyle == null) return;
 
-            if (windowBorderStyle.Setters.FirstOrDefault(setterBase => setterBase is Setter setter && setter.Property == UIElement.EffectProperty) is Setter effectSetter)
-            {
-                windowBorderStyle.Setters.Remove(effectSetter);
-            }
+            // Get a new unsealed style based on the old one, and copy Resources and Triggers
+            var newWindowBorderStyle = new Style(typeof(Border));
+            ThemeHelper.CopyStyle(windowBorderStyle, newWindowBorderStyle);
 
-            if (windowBorderStyle.Setters.FirstOrDefault(setterBase => setterBase is Setter setter && setter.Property == FrameworkElement.MarginProperty) is Setter marginSetter)
+            // Copy Setters, excluding the Effect setter and updating the Margin setter
+            foreach (var setterBase in windowBorderStyle.Setters)
             {
-                var currentMargin = (Thickness)marginSetter.Value;
-                var newMargin = new Thickness(
-                    currentMargin.Left - ShadowExtraMargin,
-                    currentMargin.Top - ShadowExtraMargin,
-                    currentMargin.Right - ShadowExtraMargin,
-                    currentMargin.Bottom - ShadowExtraMargin);
-                marginSetter.Value = newMargin;
+                if (setterBase is Setter setter)
+                {
+                    // Skip existing Effect (We'll remove it)
+                    if (setter.Property == UIElement.EffectProperty) continue;
+
+                    // Update Margin by subtracting the extra margin we added for the shadow
+                    if (setter.Property == FrameworkElement.MarginProperty)
+                    {
+                        var currentMargin = (Thickness)setter.Value;
+                        var newMargin = new Thickness(
+                            currentMargin.Left - ShadowExtraMargin,
+                            currentMargin.Top - ShadowExtraMargin,
+                            currentMargin.Right - ShadowExtraMargin,
+                            currentMargin.Bottom - ShadowExtraMargin);
+                        ThemeHelper.ReplaceSetter(newWindowBorderStyle, new Setter(FrameworkElement.MarginProperty, newMargin));
+                        continue;
+                    }
+                }
+
+                newWindowBorderStyle.Setters.Add(setterBase);
             }
 
             SetResizeBoarderThickness(null);
 
-            UpdateResourceDictionary(dict);
+            Application.Current.Resources["WindowBorderStyle"] = newWindowBorderStyle;
         }
 
         public void SetResizeBorderThickness(WindowChrome windowChrome, bool fixedWindowSize)
@@ -669,13 +707,11 @@ private void SetBlurForWindow(string theme, BackdropTypes backdropType)
                 // If the BackdropType is Mica or MicaAlt, set the windowborderstyle's background to transparent
                 if (backdropType is BackdropTypes.Mica or BackdropTypes.MicaAlt)
                 {
-                    windowBorderStyle.Setters.Remove(windowBorderStyle.Setters.OfType<Setter>().FirstOrDefault(x => x.Property == Control.BackgroundProperty));
-                    windowBorderStyle.Setters.Add(new Setter(Border.BackgroundProperty, ThemeHelper.GetFrozenSolidColorBrush(Color.FromArgb(1, 0, 0, 0))));
+                    ThemeHelper.ReplaceSetter(windowBorderStyle, new Setter(Border.BackgroundProperty, ThemeHelper.GetFrozenSolidColorBrush(Color.FromArgb(1, 0, 0, 0))));
                 }
                 else if (backdropType == BackdropTypes.Acrylic)
                 {
-                    windowBorderStyle.Setters.Remove(windowBorderStyle.Setters.OfType<Setter>().FirstOrDefault(x => x.Property == Control.BackgroundProperty));
-                    windowBorderStyle.Setters.Add(new Setter(Border.BackgroundProperty, Brushes.Transparent));
+                    ThemeHelper.ReplaceSetter(windowBorderStyle, new Setter(Border.BackgroundProperty, Brushes.Transparent));
                 }
 
                 // For themes with blur enabled, the window border is rendered by the system, so it's treated as a simple rectangle regardless of thickness.

Flow.Launcher.Core/Resource/ThemeHelper.cs

@@ -8,10 +8,10 @@ public static class ThemeHelper
 {
     public static void CopyStyle(Style originalStyle, Style targetStyle)
     {
-        // If the style is based on another style, copy the base style first
+        // If the style is based on another style, use the same base style for the target style
         if (originalStyle.BasedOn != null)
         {
-            CopyStyle(originalStyle.BasedOn, targetStyle);
+            targetStyle.BasedOn = originalStyle.BasedOn;
         }
 
         // Copy the setters from the original style
@@ -21,6 +21,15 @@ public static void CopyStyle(Style originalStyle, Style targetStyle)
         }
     }
 
+    public static void ReplaceSetter(Style style, Setter setter)
+    {
+        var existingSetter = style.Setters.OfType<Setter>().FirstOrDefault(s => s.Property == setter.Property);
+        if (existingSetter != null)
+            style.Setters.Remove(existingSetter);
+
+        style.Setters.Add(setter);
+    }
+
     public static SolidColorBrush GetFrozenSolidColorBrush(Color color)
     {
         var brush = new SolidColorBrush(color);