Add Scrollbar Context Menu (#19413)

* Scroll Bar Context Menu V1

* Add resource files

* Use InvariantResources file

* Add Unit Tests

* Refactor to XAML

* Add pointer type

* Add tests

src/Avalonia.Base/Input/ContextRequestedEventArgs.cs

@@ -67,5 +67,7 @@ namespace Avalonia.Input
         }
 
         internal bool IsHolding => _holdRoutedEventArgs != null;
+
+        internal PointerType? PointerType => _pointerEventArgs?.Pointer.Type;
     }
 }

src/Avalonia.Controls/Primitives/ScrollBar.cs

@@ -5,6 +5,7 @@ using Avalonia.Input;
 using Avalonia.Layout;
 using Avalonia.Threading;
 using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Templates;
 using Avalonia.Automation.Peers;
 using Avalonia.VisualTree;
 using Avalonia.Reactive;
@@ -86,6 +87,7 @@ namespace Avalonia.Controls.Primitives
         private CompositeDisposable? _ownerSubscriptions;
         private ScrollViewer? _owner;
         private bool _isDragging;
+        private Point _lastRightClickPosition;
 
         /// <summary>
         /// Initializes static members of the <see cref="ScrollBar"/> class. 
@@ -105,6 +107,7 @@ namespace Avalonia.Controls.Primitives
         public ScrollBar()
         {
             UpdatePseudoClasses(Orientation);
+            ContextRequested += OnContextRequested;
         }
 
         /// <summary>
@@ -521,5 +524,113 @@ namespace Avalonia.Controls.Primitives
             PseudoClasses.Set(":vertical", o == Orientation.Vertical);
             PseudoClasses.Set(":horizontal", o == Orientation.Horizontal);
         }
+
+        protected override void OnPointerPressed(PointerPressedEventArgs e)
+        {
+            base.OnPointerPressed(e);
+
+            if (e.GetCurrentPoint(this).Properties.IsRightButtonPressed)
+            {
+                _lastRightClickPosition = e.GetPosition(this);
+            }
+        }
+
+        private void OnContextRequested(object? sender, ContextRequestedEventArgs e)
+        {
+            if (e.PointerType is PointerType.Touch or PointerType.Pen)
+            {
+                e.Handled = true;
+                return;
+            }
+
+            if (e.TryGetPosition(this, out var position))
+            {
+                _lastRightClickPosition = position;
+            }
+        }
+
+        /// <summary>
+        /// Scrolls to the location at which the context menu was most recently requested.
+        /// </summary>
+        public void ScrollHere()
+        {
+            if (Track is not { } track)
+            {
+                return;
+            }
+
+            var trackLength = Orientation == Orientation.Vertical ? track.Bounds.Height : track.Bounds.Width;
+            var thumbLength = Orientation == Orientation.Vertical ? track.Thumb?.Bounds.Height ?? 0 : track.Thumb?.Bounds.Width ?? 0;
+            var clickPosition = Orientation == Orientation.Vertical ? _lastRightClickPosition.Y : _lastRightClickPosition.X;
+
+            if (trackLength > thumbLength)
+            {
+                var ratio = clickPosition / trackLength;
+                var range = Maximum - Minimum;
+                var value = Minimum + (ratio * range);
+                SetCurrentValue(ValueProperty, Math.Max(Minimum, Math.Min(Maximum, value)));
+                OnScroll(ScrollEventType.ThumbTrack);
+            }
+        }
+
+        /// <summary>
+        /// Scrolls to the top (or left edge) of the scrollbar by setting <see cref="RangeBase.Value"/> to <see cref="RangeBase.Minimum"/>.
+        /// </summary>
+        public void ScrollToHome()
+        {
+            SetCurrentValue(ValueProperty, Minimum);
+            OnScroll(ScrollEventType.SmallDecrement);
+        }
+
+        /// <summary>
+        /// Scrolls to the bottom (or right edge) of the scrollbar by setting <see cref="RangeBase.Value"/> to <see cref="RangeBase.Maximum"/>.
+        /// </summary>
+        public void ScrollToEnd()
+        {
+            SetCurrentValue(ValueProperty, Maximum);
+            OnScroll(ScrollEventType.SmallIncrement);
+        }
+
+        /// <summary>
+        /// Scrolls up by one <see cref="RangeBase.LargeChange"/> (a page) on a vertical scrollbar.
+        /// </summary>
+        public void PageUp() => LargeDecrement();
+
+        /// <summary>
+        /// Scrolls down by one <see cref="RangeBase.LargeChange"/> (a page) on a vertical scrollbar.
+        /// </summary>
+        public void PageDown() => LargeIncrement();
+
+        /// <summary>
+        /// Scrolls left by one <see cref="RangeBase.LargeChange"/> (a page) on a horizontal scrollbar.
+        /// </summary>
+        public void PageLeft() => LargeDecrement();
+
+        /// <summary>
+        /// Scrolls right by one <see cref="RangeBase.LargeChange"/> (a page) on a horizontal scrollbar.
+        /// </summary>
+        public void PageRight() => LargeIncrement();
+
+        /// <summary>
+        /// Scrolls up by one <see cref="RangeBase.SmallChange"/> on a vertical scrollbar.
+        /// </summary>
+        public void LineUp() => SmallDecrement();
+
+        /// <summary>
+        /// Scrolls down by one <see cref="RangeBase.SmallChange"/> on a vertical scrollbar.
+        /// </summary>
+        public void LineDown() => SmallIncrement();
+
+        /// <summary>
+        /// Scrolls left by one <see cref="RangeBase.SmallChange"/> on a horizontal scrollbar.
+        /// </summary>
+        public void LineLeft() => SmallDecrement();
+
+        /// <summary>
+        /// Scrolls right by one <see cref="RangeBase.SmallChange"/> on a horizontal scrollbar.
+        /// </summary>
+        public void LineRight() => SmallIncrement();
+
+        private Track? Track => this.GetTemplateDescendants().OfType<Track>().FirstOrDefault();
     }
 }

src/Avalonia.Themes.Fluent/Controls/ScrollBar.xaml

@@ -18,6 +18,32 @@
     </Border>
   </Design.PreviewWith>
 
+  <MenuFlyout x:Key="VerticalScrollBarContextFlyout">
+    <MenuItem Header="{DynamicResource StringScrollBarScrollHere}" Command="{Binding $parent[ScrollBar].ScrollHere}" AutomationProperties.AutomationId="ScrollHere" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarTop}" Command="{Binding $parent[ScrollBar].ScrollToHome}" AutomationProperties.AutomationId="Top" />
+    <MenuItem Header="{DynamicResource StringScrollBarBottom}" Command="{Binding $parent[ScrollBar].ScrollToEnd}" AutomationProperties.AutomationId="Bottom" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarPageUp}" Command="{Binding $parent[ScrollBar].PageUp}" AutomationProperties.AutomationId="PageUp" />
+    <MenuItem Header="{DynamicResource StringScrollBarPageDown}" Command="{Binding $parent[ScrollBar].PageDown}" AutomationProperties.AutomationId="PageDown" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollUp}" Command="{Binding $parent[ScrollBar].LineUp}" AutomationProperties.AutomationId="ScrollUp" />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollDown}" Command="{Binding $parent[ScrollBar].LineDown}" AutomationProperties.AutomationId="ScrollDown" />
+  </MenuFlyout>
+
+  <MenuFlyout x:Key="HorizontalScrollBarContextFlyout">
+    <MenuItem Header="{DynamicResource StringScrollBarScrollHere}" Command="{Binding $parent[ScrollBar].ScrollHere}" AutomationProperties.AutomationId="ScrollHere" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarLeftEdge}" Command="{Binding $parent[ScrollBar].ScrollToHome}" AutomationProperties.AutomationId="LeftEdge" />
+    <MenuItem Header="{DynamicResource StringScrollBarRightEdge}" Command="{Binding $parent[ScrollBar].ScrollToEnd}" AutomationProperties.AutomationId="RightEdge" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarPageLeft}" Command="{Binding $parent[ScrollBar].PageLeft}" AutomationProperties.AutomationId="PageLeft" />
+    <MenuItem Header="{DynamicResource StringScrollBarPageRight}" Command="{Binding $parent[ScrollBar].PageRight}" AutomationProperties.AutomationId="PageRight" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollLeft}" Command="{Binding $parent[ScrollBar].LineLeft}" AutomationProperties.AutomationId="ScrollLeft" />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollRight}" Command="{Binding $parent[ScrollBar].LineRight}" AutomationProperties.AutomationId="ScrollRight" />
+  </MenuFlyout>
+
   <ControlTheme x:Key="FluentScrollBarThumb" TargetType="Thumb">
     <Setter Property="Background" Value="{DynamicResource ScrollBarPanningThumbBackground}"/>
     <Setter Property="Template">
@@ -111,6 +137,7 @@
     <Setter Property="BorderBrush" Value="{DynamicResource ScrollBarBorderBrush}" />
 
     <Style Selector="^:vertical">
+      <Setter Property="ContextFlyout" Value="{StaticResource VerticalScrollBarContextFlyout}" />
       <Setter Property="Template">
         <ControlTemplate>
           <Grid x:Name="Root">
@@ -194,6 +221,7 @@
     </Style>
 
     <Style Selector="^:horizontal">
+      <Setter Property="ContextFlyout" Value="{StaticResource HorizontalScrollBarContextFlyout}" />
       <Setter Property="Template">
         <ControlTemplate>
           <Grid x:Name="Root">

src/Avalonia.Themes.Fluent/Strings/InvariantResources.xaml

@@ -25,5 +25,18 @@
   <x:String x:Key="StringManagedFileChooserOverwritePromptFileAlreadyExistsText">{0} already exists. Do you want to replace it?</x:String>
   <x:String x:Key="StringManagedFileChooserOverwritePromptConfirmText">Yes</x:String>
   <x:String x:Key="StringManagedFileChooserOverwritePromptCancelText">No</x:String>
+  <x:String x:Key="StringScrollBarScrollHere">Scroll Here</x:String>
+  <x:String x:Key="StringScrollBarTop">Top</x:String>
+  <x:String x:Key="StringScrollBarBottom">Bottom</x:String>
+  <x:String x:Key="StringScrollBarPageUp">Page Up</x:String>
+  <x:String x:Key="StringScrollBarPageDown">Page Down</x:String>
+  <x:String x:Key="StringScrollBarScrollUp">Scroll Up</x:String>
+  <x:String x:Key="StringScrollBarScrollDown">Scroll Down</x:String>
+  <x:String x:Key="StringScrollBarLeftEdge">Left Edge</x:String>
+  <x:String x:Key="StringScrollBarRightEdge">Right Edge</x:String>
+  <x:String x:Key="StringScrollBarPageLeft">Page Left</x:String>
+  <x:String x:Key="StringScrollBarPageRight">Page Right</x:String>
+  <x:String x:Key="StringScrollBarScrollLeft">Scroll Left</x:String>
+  <x:String x:Key="StringScrollBarScrollRight">Scroll Right</x:String>
 </ResourceDictionary>
 

src/Avalonia.Themes.Simple/Controls/ScrollBar.xaml

@@ -1,11 +1,38 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     x:ClassModifier="internal">
+  <MenuFlyout x:Key="SimpleVerticalScrollBarContextFlyout">
+    <MenuItem Header="{DynamicResource StringScrollBarScrollHere}" Command="{Binding $parent[ScrollBar].ScrollHere}" AutomationProperties.AutomationId="ScrollHere" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarTop}" Command="{Binding $parent[ScrollBar].ScrollToHome}" AutomationProperties.AutomationId="Top" />
+    <MenuItem Header="{DynamicResource StringScrollBarBottom}" Command="{Binding $parent[ScrollBar].ScrollToEnd}" AutomationProperties.AutomationId="Bottom" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarPageUp}" Command="{Binding $parent[ScrollBar].PageUp}" AutomationProperties.AutomationId="PageUp" />
+    <MenuItem Header="{DynamicResource StringScrollBarPageDown}" Command="{Binding $parent[ScrollBar].PageDown}" AutomationProperties.AutomationId="PageDown" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollUp}" Command="{Binding $parent[ScrollBar].LineUp}" AutomationProperties.AutomationId="ScrollUp" />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollDown}" Command="{Binding $parent[ScrollBar].LineDown}" AutomationProperties.AutomationId="ScrollDown" />
+  </MenuFlyout>
+
+  <MenuFlyout x:Key="SimpleHorizontalScrollBarContextFlyout">
+    <MenuItem Header="{DynamicResource StringScrollBarScrollHere}" Command="{Binding $parent[ScrollBar].ScrollHere}" AutomationProperties.AutomationId="ScrollHere" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarLeftEdge}" Command="{Binding $parent[ScrollBar].ScrollToHome}" AutomationProperties.AutomationId="LeftEdge" />
+    <MenuItem Header="{DynamicResource StringScrollBarRightEdge}" Command="{Binding $parent[ScrollBar].ScrollToEnd}" AutomationProperties.AutomationId="RightEdge" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarPageLeft}" Command="{Binding $parent[ScrollBar].PageLeft}" AutomationProperties.AutomationId="PageLeft" />
+    <MenuItem Header="{DynamicResource StringScrollBarPageRight}" Command="{Binding $parent[ScrollBar].PageRight}" AutomationProperties.AutomationId="PageRight" />
+    <Separator />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollLeft}" Command="{Binding $parent[ScrollBar].LineLeft}" AutomationProperties.AutomationId="ScrollLeft" />
+    <MenuItem Header="{DynamicResource StringScrollBarScrollRight}" Command="{Binding $parent[ScrollBar].LineRight}" AutomationProperties.AutomationId="ScrollRight" />
+  </MenuFlyout>
+
   <ControlTheme x:Key="{x:Type ScrollBar}"
                 TargetType="ScrollBar">
     <Setter Property="Cursor" Value="Arrow" />
 
     <Style Selector="^:horizontal">
+      <Setter Property="ContextFlyout" Value="{StaticResource SimpleHorizontalScrollBarContextFlyout}" />
       <Setter Property="Height" Value="{DynamicResource ScrollBarThickness}" />
       <Setter Property="Template">
         <ControlTemplate>
@@ -62,6 +89,7 @@
       </Setter>
     </Style>
     <Style Selector="^:vertical">
+      <Setter Property="ContextFlyout" Value="{StaticResource SimpleVerticalScrollBarContextFlyout}" />
       <Setter Property="Width" Value="{DynamicResource ScrollBarThickness}" />
       <Setter Property="Template">
         <ControlTemplate>

tests/Avalonia.Controls.UnitTests/Primitives/ScrollBarTests.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Linq;
+using Avalonia.Automation;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
+using Avalonia.Layout;
 using Avalonia.Media;
 using Avalonia.UnitTests;
 using Xunit;
@@ -194,5 +196,225 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 Background = Brushes.Gray,
             };
         }
+
+        [Theory]
+        [InlineData(Orientation.Vertical)]
+        [InlineData(Orientation.Horizontal)]
+        public void Orientation_Should_Set_Matching_PseudoClass(Orientation orientation)
+        {
+            var target = new ScrollBar { Orientation = orientation };
+
+            Assert.Equal(orientation == Orientation.Vertical, target.Classes.Contains(":vertical"));
+            Assert.Equal(orientation == Orientation.Horizontal, target.Classes.Contains(":horizontal"));
+        }
+
+        [Fact]
+        public void ScrollToHome_Should_Set_Value_To_Minimum()
+        {
+            var target = CreateScrollBar(minimum: 10, maximum: 100, value: 50);
+
+            target.ScrollToHome();
+
+            Assert.Equal(10, target.Value);
+        }
+
+        [Fact]
+        public void ScrollToEnd_Should_Set_Value_To_Maximum()
+        {
+            var target = CreateScrollBar(minimum: 0, maximum: 90, value: 50);
+
+            target.ScrollToEnd();
+
+            Assert.Equal(90, target.Value);
+        }
+
+        [Fact]
+        public void PageUp_Should_Decrease_Value_By_LargeChange()
+        {
+            var target = CreateScrollBar(value: 50, largeChange: 10);
+
+            target.PageUp();
+
+            Assert.Equal(40, target.Value);
+        }
+
+        [Fact]
+        public void PageDown_Should_Increase_Value_By_LargeChange()
+        {
+            var target = CreateScrollBar(value: 50, largeChange: 10);
+
+            target.PageDown();
+
+            Assert.Equal(60, target.Value);
+        }
+
+        [Fact]
+        public void PageLeft_Should_Decrease_Value_By_LargeChange()
+        {
+            var target = CreateScrollBar(orientation: Orientation.Horizontal, value: 50, largeChange: 10);
+
+            target.PageLeft();
+
+            Assert.Equal(40, target.Value);
+        }
+
+        [Fact]
+        public void PageRight_Should_Increase_Value_By_LargeChange()
+        {
+            var target = CreateScrollBar(orientation: Orientation.Horizontal, value: 50, largeChange: 10);
+
+            target.PageRight();
+
+            Assert.Equal(60, target.Value);
+        }
+
+        [Fact]
+        public void LineUp_Should_Decrease_Value_By_SmallChange()
+        {
+            var target = CreateScrollBar(value: 50, smallChange: 5);
+
+            target.LineUp();
+
+            Assert.Equal(45, target.Value);
+        }
+
+        [Fact]
+        public void LineDown_Should_Increase_Value_By_SmallChange()
+        {
+            var target = CreateScrollBar(value: 50, smallChange: 5);
+
+            target.LineDown();
+
+            Assert.Equal(55, target.Value);
+        }
+
+        [Fact]
+        public void LineLeft_Should_Decrease_Value_By_SmallChange()
+        {
+            var target = CreateScrollBar(orientation: Orientation.Horizontal, value: 50, smallChange: 5);
+
+            target.LineLeft();
+
+            Assert.Equal(45, target.Value);
+        }
+
+        [Fact]
+        public void LineRight_Should_Increase_Value_By_SmallChange()
+        {
+            var target = CreateScrollBar(orientation: Orientation.Horizontal, value: 50, smallChange: 5);
+
+            target.LineRight();
+
+            Assert.Equal(55, target.Value);
+        }
+
+        [Fact]
+        public void Scroll_Methods_Should_Respect_Value_Bounds()
+        {
+            var target = CreateScrollBar(minimum: 20, maximum: 80, value: 25, smallChange: 10);
+
+            target.LineUp();
+            Assert.Equal(20, target.Value); // Should not go below Minimum
+
+            target.Value = 75;
+            target.LineDown();
+            Assert.Equal(80, target.Value); // Should not go above Maximum
+        }
+
+        [Fact]
+        public void Scroll_Methods_Should_Raise_Scroll_Event()
+        {
+            var target = CreateScrollBar(value: 50, smallChange: 5, largeChange: 10);
+            var events = new System.Collections.Generic.List<ScrollEventType>();
+            target.Scroll += (_, e) => events.Add(e.ScrollEventType);
+
+            target.LineDown();
+            target.PageDown();
+            target.ScrollToHome();
+            target.ScrollToEnd();
+
+            Assert.Equal(
+                new[]
+                {
+                    ScrollEventType.SmallIncrement,
+                    ScrollEventType.LargeIncrement,
+                    ScrollEventType.SmallDecrement,
+                    ScrollEventType.SmallIncrement,
+                },
+                events);
+        }
+
+        [Fact]
+        public void ScrollHere_Should_Set_Value_Within_Bounds()
+        {
+            var target = CreateScrollBar(minimum: 0, maximum: 100, value: 0);
+
+            // No exception even though no pointer position was recorded yet.
+            target.ScrollHere();
+
+            Assert.InRange(target.Value, target.Minimum, target.Maximum);
+        }
+
+        [Theory]
+        [InlineData(PointerType.Touch)]
+        [InlineData(PointerType.Pen)]
+        public void ContextRequested_Should_Be_Handled_For_Touch_Or_Pen_Input(PointerType pointerType)
+        {
+            var target = CreateScrollBar();
+
+            var args = CreateContextRequested(target, pointerType);
+            target.RaiseEvent(args);
+
+            Assert.True(args.Handled);
+        }
+
+        [Fact]
+        public void ContextRequested_Should_Not_Be_Handled_For_Mouse_Input()
+        {
+            var target = CreateScrollBar();
+
+            var args = CreateContextRequested(target, PointerType.Mouse);
+            target.RaiseEvent(args);
+
+            Assert.False(args.Handled);
+        }
+
+        private static ContextRequestedEventArgs CreateContextRequested(ScrollBar target, PointerType pointerType)
+        {
+            var pointer = new Pointer(Pointer.GetNextFreeId(), pointerType, true);
+            var pointerArgs = new PointerPressedEventArgs(
+                target,
+                pointer,
+                target,
+                default,
+                timestamp: 1,
+                new PointerPointProperties(RawInputModifiers.None, PointerUpdateKind.Other),
+                KeyModifiers.None);
+
+            return new ContextRequestedEventArgs(pointerArgs);
+        }
+
+        private static ScrollBar CreateScrollBar(
+            Orientation orientation = Orientation.Vertical,
+            double minimum = 0,
+            double maximum = 100,
+            double value = 0,
+            double smallChange = 1,
+            double largeChange = 10)
+        {
+            var target = new ScrollBar
+            {
+                Orientation = orientation,
+                Template = new FuncControlTemplate<ScrollBar>(Template),
+                Minimum = minimum,
+                Maximum = maximum,
+                Value = value,
+                SmallChange = smallChange,
+                LargeChange = largeChange,
+            };
+
+            target.ApplyTemplate();
+            return target;
+        }
     }
 }