refactor: replace Border with MacOSTrafficLightsSpacer to hold the area of macOS traffic lights

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/Views/ChromelessWindow.cs

@@ -1,5 +1,5 @@
 using System;
-using Avalonia;
+
 using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
@@ -8,15 +8,6 @@ namespace SourceGit.Views
 {
     public class ChromelessWindow : Window
     {
-        public static readonly StyledProperty<double> MacOSWindowButtonWidthProperty =
-            AvaloniaProperty.Register<ChromelessWindow, double>(nameof(MacOSWindowButtonWidth), 76.0);
-
-        public double MacOSWindowButtonWidth
-        {
-            get => GetValue(MacOSWindowButtonWidthProperty);
-            set => SetValue(MacOSWindowButtonWidthProperty, value);
-        }
-
         public bool UseSystemWindowFrame
         {
             get => Native.OS.UseSystemWindowFrame;
@@ -32,7 +23,6 @@ public bool CloseOnESC
 
         public ChromelessWindow()
         {
-            MacOSWindowButtonWidth = 76.0 / Math.Max(1.0, ViewModels.Preferences.Instance.Zoom);
             Focusable = true;
             Native.OS.SetupForWindow(this);
         }
@@ -104,14 +94,12 @@ protected override void OnKeyDown(KeyEventArgs e)
                 {
                     var zoom = Math.Min(ViewModels.Preferences.Instance.Zoom + 0.05, 2.5);
                     ViewModels.Preferences.Instance.Zoom = zoom;
-                    MacOSWindowButtonWidth = 76.0 / zoom;
                     e.Handled = true;
                 }
                 else if (e.Key == Key.OemMinus)
                 {
                     var zoom = Math.Max(ViewModels.Preferences.Instance.Zoom - 0.05, 1);
                     ViewModels.Preferences.Instance.Zoom = zoom;
-                    MacOSWindowButtonWidth = 76.0 / zoom;
                     e.Handled = true;
                 }
             }

src/Views/Launcher.axaml

@@ -28,7 +28,9 @@
               PointerPressed="BeginMoveWindow"/>
 
       <!-- Caption Buttons (macOS) -->
-      <Border Grid.Column="0" Width="{Binding #ThisControl.MacOSWindowButtonWidth}" IsVisible="{Binding #ThisControl.HasLeftCaptionButton}"/>
+      <v:MacOSTrafficLightsSpacer Grid.Column="0"
+                                  Zoom="{Binding Source={x:Static vm:Preferences.Instance}, Path=Zoom, Mode=OneWay}"
+                                  IsVisible="{Binding #ThisControl.HasLeftCaptionButton}"/>
 
       <!-- Menu (Windows/Linux) -->
       <Button Grid.Column="0" Classes="icon_button" VerticalAlignment="Bottom" Margin="6,0,0,3" IsVisible="{OnPlatform True, macOS=False}">

src/Views/MacOSTrafficLightsSpacer.cs

@@ -0,0 +1,35 @@
+using Avalonia;
+using Avalonia.Controls;
+
+namespace SourceGit.Views
+{
+    public class MacOSTrafficLightsSpacer : Control
+    {
+        public static readonly StyledProperty<double> ZoomProperty =
+            AvaloniaProperty.Register<MacOSTrafficLightsSpacer, double>(nameof(Zoom), 1.0);
+
+        public double Zoom
+        {
+            get => GetValue(ZoomProperty);
+            set => SetValue(ZoomProperty, value);
+        }
+
+        public MacOSTrafficLightsSpacer()
+        {
+            IsHitTestVisible = false;
+        }
+
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == ZoomProperty)
+                InvalidateMeasure();
+        }
+
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            return new Size(76.0 / Zoom, 24.0);
+        }
+    }
+}