Refactor brush creation with ThemeHelper utility

Introduce ThemeHelper.GetFreezeSolidColorBrush to centralize and reuse SolidColorBrush creation and freezing logic. Refactor Theme.cs to use this helper, improving code clarity and maintainability. Also, use Brushes.Transparent directly where appropriate.

Author: Jack251970

Flow.Launcher.Core/Resource/Theme.cs

@@ -674,16 +674,12 @@ private void SetBlurForWindow(string theme, BackdropTypes backdropType)
                 if (backdropType == BackdropTypes.Mica || backdropType == BackdropTypes.MicaAlt)
                 {
                     windowBorderStyle.Setters.Remove(windowBorderStyle.Setters.OfType<Setter>().FirstOrDefault(x => x.Property == Control.BackgroundProperty));
-                    var brush = new SolidColorBrush(Color.FromArgb(1, 0, 0, 0));
-                    brush.Freeze();
-                    windowBorderStyle.Setters.Add(new Setter(Border.BackgroundProperty, brush));
+                    windowBorderStyle.Setters.Add(new Setter(Border.BackgroundProperty, ThemeHelper.GetFreezeSolidColorBrush(Color.FromArgb(1, 0, 0, 0))));
                 }
                 else if (backdropType == BackdropTypes.Acrylic)
                 {
                     windowBorderStyle.Setters.Remove(windowBorderStyle.Setters.OfType<Setter>().FirstOrDefault(x => x.Property == Control.BackgroundProperty));
-                    var brush = new SolidColorBrush(Colors.Transparent);
-                    brush.Freeze();
-                    windowBorderStyle.Setters.Add(new Setter(Border.BackgroundProperty, brush));
+                    windowBorderStyle.Setters.Add(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.
@@ -806,10 +802,8 @@ private void ApplyPreviewBackground(Color? bgColor = null)
             }
 
             // Apply background color (remove transparency in color)
-            Color backgroundColor = Color.FromRgb(bgColor.Value.R, bgColor.Value.G, bgColor.Value.B);
-            var brush = new SolidColorBrush(backgroundColor);
-            brush.Freeze();
-            previewStyle.Setters.Add(new Setter(Border.BackgroundProperty, brush));
+            var backgroundColor = Color.FromRgb(bgColor.Value.R, bgColor.Value.G, bgColor.Value.B);
+            previewStyle.Setters.Add(new Setter(Border.BackgroundProperty, ThemeHelper.GetFreezeSolidColorBrush(backgroundColor)));
 
             // The blur theme keeps the corner round fixed (applying DWM code to modify it causes rendering issues).
             // The non-blur theme retains the previously set WindowBorderStyle.
@@ -923,15 +917,11 @@ private void ColorizeWindow(string theme, BackdropTypes backdropType)
                 // Only set the background to transparent if the theme supports blur
                 if (backdropType == BackdropTypes.Mica || backdropType == BackdropTypes.MicaAlt)
                 {
-                    var backgroundBrush = new SolidColorBrush(Color.FromArgb(1, 0, 0, 0));
-                    backgroundBrush.Freeze();
-                    mainWindow.Background = backgroundBrush;
+                    mainWindow.Background = ThemeHelper.GetFreezeSolidColorBrush(Color.FromArgb(1, 0, 0, 0));
                 }
                 else
                 {
-                    var backgroundBrush = new SolidColorBrush(selectedBG);
-                    backgroundBrush.Freeze();
-                    mainWindow.Background = backgroundBrush;
+                    mainWindow.Background = ThemeHelper.GetFreezeSolidColorBrush(selectedBG);
                 }
             }
         }

Flow.Launcher.Core/Resource/ThemeHelper.cs

@@ -0,0 +1,13 @@
+using System.Windows.Media;
+
+namespace Flow.Launcher.Core.Resource;
+
+public static class ThemeHelper
+{
+    public static SolidColorBrush GetFreezeSolidColorBrush(Color color)
+    {
+        var brush = new SolidColorBrush(color);
+        brush.Freeze();
+        return brush;
+    }
+}