refactor: custom renderer for launcher tab bar

Author: love-linger

src/Resources/Styles.axaml

@@ -627,10 +627,6 @@
     </Setter>
   </Style>
 
-  <Style Selector="Border.launcher_pagetab">
-    <Setter Property="Background" Value="Transparent"/>
-    <Setter Property="BorderBrush" Value="Transparent"/>
-  </Style>
   <Style Selector="ListBox.launcher_page_tabbar">
     <Setter Property="Background" Value="Transparent"/>
   </Style>
@@ -642,15 +638,13 @@
     <Setter Property="Opacity" Value=".5"/>
   </Style>
   <Style Selector="ListBox.launcher_page_tabbar ListBoxItem:pointerover /template/ ContentPresenter#PART_ContentPresenter">
+    <Setter Property="Background" Value="Transparent"/>
     <Setter Property="Opacity" Value=".85"/>
   </Style>
   <Style Selector="ListBox.launcher_page_tabbar ListBoxItem:selected /template/ ContentPresenter#PART_ContentPresenter">
+    <Setter Property="Background" Value="Transparent"/>
     <Setter Property="Opacity" Value="1"/>
   </Style>
-  <Style Selector="ListBoxItem:selected Border.launcher_pagetab">
-    <Setter Property="Background" Value="{DynamicResource Brush.ToolBar}"/>
-    <Setter Property="BorderBrush" Value="{DynamicResource Brush.Border0}"/>
-  </Style>
 
   <Style Selector="ContextMenu">
     <Setter Property="HorizontalOffset" Value="-4"/>

src/ViewModels/Launcher.cs

@@ -24,10 +24,7 @@ public LauncherPage ActivePage
             set
             {
                 if (SetProperty(ref _activePage, value))
-                {
                     PopupHost.Active = value;
-                    UpdateTabSplitterVisible();
-                }
             }
         }
 
@@ -69,9 +66,7 @@ public Launcher()
 
                 var lastActiveIdx = Preference.Instance.LastActiveTabIdx;
                 if (lastActiveIdx >= 0 && lastActiveIdx < Pages.Count)
-                {
                     ActivePage = Pages[lastActiveIdx];
-                }
             }
         }
 
@@ -161,13 +156,11 @@ public void CloseTab(LauncherPage page)
                 ActivePage = Pages[removeIdx == Pages.Count - 1 ? removeIdx - 1 : removeIdx + 1];
                 CloseRepositoryInTab(page);
                 Pages.RemoveAt(removeIdx);
-                UpdateTabSplitterVisible();
             }
             else if (removeIdx + 1 == activeIdx)
             {
                 CloseRepositoryInTab(page);
                 Pages.RemoveAt(removeIdx);
-                UpdateTabSplitterVisible();
             }
             else
             {
@@ -365,13 +358,6 @@ private void CloseRepositoryInTab(LauncherPage page)
             page.Data = null;
         }
 
-        private void UpdateTabSplitterVisible()
-        {
-            var activePageIdx = ActivePage == null ? -1 : Pages.IndexOf(ActivePage);
-            for (int i = 0; i < Pages.Count; i++)
-                Pages[i].IsTabSplitterVisible = (activePageIdx != i && activePageIdx != i + 1);
-        }
-
         private LauncherPage _activePage = null;
     }
 }

src/ViewModels/LauncherPage.cs

@@ -18,12 +18,6 @@ public object Data
             set => SetProperty(ref _data, value);
         }
 
-        public bool IsTabSplitterVisible
-        {
-            get => _isTabSplitterVisible;
-            set => SetProperty(ref _isTabSplitterVisible, value);
-        }
-
         public AvaloniaList<Notification> Notifications
         {
             get;
@@ -55,6 +49,5 @@ public void CopyPath()
 
         private RepositoryNode _node = null;
         private object _data = null;
-        private bool _isTabSplitterVisible = true;
     }
 }

src/Views/Launcher.axaml

@@ -37,11 +37,7 @@
       </Border>
 
       <!-- Menu (Windows/Linux) -->
-      <Button Grid.Column="0" Classes="icon_button" VerticalAlignment="Bottom" IsVisible="{OnPlatform True, macOS=False}">
-        <Button.Margin>
-          <OnPlatform Default="4,0,2,3" macOS="4,0,6,3"/>
-        </Button.Margin>
-        
+      <Button Grid.Column="0" Classes="icon_button" VerticalAlignment="Bottom" Margin="6,0,2,3" IsVisible="{OnPlatform True, macOS=False}">
         <Button.Flyout>
           <MenuFlyout Placement="BottomEdgeAlignedLeft" VerticalOffset="-8">
             <MenuItem Header="{DynamicResource Text.Preference}" Command="{x:Static s:App.OpenPreferenceCommand}" InputGesture="Ctrl+Shift+P">

src/Views/LauncherTabBar.axaml

@@ -15,17 +15,20 @@
     </RepeatButton>
 
     <ScrollViewer Grid.Column="1"
+                  Margin="6,0"
                   x:Name="LauncherTabsScroller"
                   HorizontalAlignment="Left"
                   HorizontalScrollBarVisibility="Hidden"
                   VerticalScrollBarVisibility="Disabled"
-                  PointerWheelChanged="ScrollTabs"
-                  LayoutUpdated="OnTabsLayoutUpdated">
+                  PointerWheelChanged="ScrollTabs">
       <StackPanel Orientation="Horizontal">
-        <ListBox Classes="launcher_page_tabbar"
+        <ListBox x:Name="LauncherTabsList"
+                 Classes="launcher_page_tabbar"
                  ItemsSource="{Binding Pages}"
                  SelectionMode="AlwaysSelected"
-                 SelectedItem="{Binding ActivePage, Mode=TwoWay}">
+                 SelectedItem="{Binding ActivePage, Mode=TwoWay}"
+                 SelectionChanged="OnTabsSelectionChanged"
+                 LayoutUpdated="OnTabsLayoutUpdated">
           <ListBox.ItemsPanel>
             <ItemsPanelTemplate>
               <StackPanel Orientation="Horizontal" Height="30"/>
@@ -34,10 +37,8 @@
 
           <ListBox.ItemTemplate>
             <DataTemplate DataType="{x:Type vm:LauncherPage}">
-              <Border Classes="launcher_pagetab"
-                      Height="30"
-                      BorderThickness="1,1,1,0"
-                      CornerRadius="6,6,0,0"
+              <Border Height="30"
+                      Background="Transparent"
                       PointerPressed="OnPointerPressedTab"
                       PointerMoved="OnPointerMovedOverTab"
                       PointerReleased="OnPointerReleasedTab"
@@ -86,11 +87,6 @@
                     </ToolTip.Tip>
                     <Path Width="8" Height="8" Data="{StaticResource Icons.Window.Close}"/>
                   </Button>
-                  <Rectangle Grid.Column="2"
-                             Width=".5" Height="20"
-                             HorizontalAlignment="Right" VerticalAlignment="Center"
-                             Fill="{DynamicResource Brush.FG2}"
-                             IsVisible="{Binding IsTabSplitterVisible}"/>
                 </Grid>
               </Border>
             </DataTemplate>

src/Views/LauncherTabBar.axaml.cs

@@ -4,6 +4,7 @@
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Interactivity;
+using Avalonia.Media;
 
 namespace SourceGit.Views
 {
@@ -14,6 +15,98 @@ public LauncherTabBar()
             InitializeComponent();
         }
 
+        public override void Render(DrawingContext context)
+        {
+            base.Render(context);
+
+            if (LauncherTabsList == null || LauncherTabsList.SelectedIndex == -1)
+                return;
+
+            var startX = LauncherTabsScroller.Offset.X;
+            var endX = startX + LauncherTabsScroller.Viewport.Width;
+            var height = LauncherTabsScroller.Viewport.Height;
+
+            var selectedIdx = LauncherTabsList.SelectedIndex;
+            var count = LauncherTabsList.ItemCount;
+            var separatorPen = new Pen(this.FindResource("Brush.FG2") as IBrush, 0.5);
+            var separatorY = (height - 20) * 0.5;
+            for (var i = 0; i < count; i++)
+            {
+                if (i == selectedIdx || i == selectedIdx - 1)
+                    continue;
+
+                var container = LauncherTabsList.ContainerFromIndex(i);
+                var containerEndX = container.Bounds.Right;
+                if (containerEndX < startX || containerEndX > endX)
+                    continue;
+
+                var separatorX = containerEndX - startX + LauncherTabsScroller.Bounds.X;
+                context.DrawLine(separatorPen, new Point(separatorX, separatorY), new Point(separatorX, separatorY + 20));
+            }
+
+            var selected = LauncherTabsList.ContainerFromIndex(selectedIdx);
+            var activeStartX = selected.Bounds.X;
+            var activeEndX = activeStartX + selected.Bounds.Width;
+            if (activeStartX > endX + 6 || activeEndX < startX - 6)
+                return;
+
+            var geo = new StreamGeometry();
+            var angle = Math.PI / 2;
+            var x = 0.0;
+            var y = height + 0.5;
+            using (var ctx = geo.Open())
+            {
+                var drawLeftX = activeStartX - startX + LauncherTabsScroller.Bounds.X;
+                var drawRightX = activeEndX - startX + LauncherTabsScroller.Bounds.X;
+                if (drawLeftX < LauncherTabsScroller.Bounds.X)
+                {
+                    x = LauncherTabsScroller.Bounds.X;
+                    ctx.BeginFigure(new Point(x, y), true);
+                    y = 0;
+                    ctx.LineTo(new Point(x, y));
+                    x = drawRightX - 6;
+                }
+                else
+                {
+                    x = drawLeftX - 6;
+                    ctx.BeginFigure(new Point(x, y), true);
+                    x = drawLeftX;
+                    y -= 6;
+                    ctx.ArcTo(new Point(x, y), new Size(6.5, 6.5), angle, false, SweepDirection.CounterClockwise);
+                    y = 6;
+                    ctx.LineTo(new Point(x, y));
+                    x += 6;
+                    y = 0;
+                    ctx.ArcTo(new Point(x, y), new Size(6, 6), angle, false, SweepDirection.Clockwise);
+                    x = drawRightX - 6;
+                }
+
+                if (drawRightX < LauncherTabsScroller.Bounds.Right)
+                {
+                    ctx.LineTo(new Point(x, y));
+                    x = drawRightX;
+                    y = 6;
+                    ctx.ArcTo(new Point(x, y), new Size(6, 6), angle, false, SweepDirection.Clockwise);
+                    y = height - 6;
+                    ctx.LineTo(new Point(x, y));
+                    x += 6;
+                    y = height + 0.5;
+                    ctx.ArcTo(new Point(x, y), new Size(6.5, 6.5), angle, false, SweepDirection.CounterClockwise);
+                }
+                else
+                {
+                    x = LauncherTabsScroller.Bounds.Right;
+                    ctx.LineTo(new Point(x, y));
+                    y = height + 0.5;
+                    ctx.LineTo(new Point(x, y));
+                }
+            }
+
+            var fill = this.FindResource("Brush.ToolBar") as IBrush;
+            var stroke = new Pen(this.FindResource("Brush.Border0") as IBrush, 1);
+            context.DrawGeometry(fill, stroke, geo);
+        }
+
         private void ScrollTabs(object sender, PointerWheelEventArgs e)
         {
             if (!e.KeyModifiers.HasFlag(KeyModifiers.Shift))
@@ -52,6 +145,13 @@ private void OnTabsLayoutUpdated(object sender, EventArgs e)
                 LeftScrollIndicator.IsVisible = false;
                 RightScrollIndicator.IsVisible = false;
             }
+
+            InvalidateVisual();
+        }
+
+        private void OnTabsSelectionChanged(object sender, SelectionChangedEventArgs e)
+        {
+            InvalidateVisual();
         }
 
         private void SetupDragAndDrop(object sender, RoutedEventArgs e)