Remove IInternalScroller and move IScrollable to Avalonia.Base (#20519)

* Remove IInternalScroller and move IScrollable to Avalonia.Base

* Update API suppressions

api/Avalonia.Win32.Interoperability.nupkg.xml

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <!-- https://learn.microsoft.com/dotnet/fundamentals/package-validation/diagnostic-ids -->
 <Suppressions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <Suppression>
@@ -37,4 +37,4 @@
     <Left>baseline/Avalonia.Win32.Interoperability/lib/net8.0-windows7.0/Avalonia.Win32.Interoperability.dll</Left>
     <Right>current/Avalonia.Win32.Interoperability/lib/net8.0-windows7.0/Avalonia.Win32.Interoperability.dll</Right>
   </Suppression>
-</Suppressions>
+</Suppressions>

api/Avalonia.nupkg.xml

@@ -7,6 +7,12 @@
     <Left>baseline/Avalonia/lib/net10.0/Avalonia.Base.dll</Left>
     <Right>current/Avalonia/lib/net10.0/Avalonia.Base.dll</Right>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Avalonia.Controls.Primitives.IScrollable</Target>
+    <Left>baseline/Avalonia/lib/net10.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net10.0/Avalonia.Controls.dll</Right>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings.CompiledBindingPath</Target>
@@ -25,6 +31,12 @@
     <Left>baseline/Avalonia/lib/net8.0/Avalonia.Base.dll</Left>
     <Right>current/Avalonia/lib/net8.0/Avalonia.Base.dll</Right>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Avalonia.Controls.Primitives.IScrollable</Target>
+    <Left>baseline/Avalonia/lib/net8.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net8.0/Avalonia.Controls.dll</Right>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings.CompiledBindingPath</Target>

src/Avalonia.Base/Controls/IInternalScroller.cs

@@ -1,11 +0,0 @@
-using System.Runtime.CompilerServices;
-
-namespace Avalonia.Controls.Primitives;
-
-// TODO12: Integrate with existing IScrollable interface, breaking change
-internal interface IInternalScroller
-{
-    bool CanHorizontallyScroll { get; }
-
-    bool CanVerticallyScroll { get; }
-}

src/Avalonia.Controls/IScrollable.cs → src/Avalonia.Base/Controls/Primitives/IScrollable.cs

@@ -19,5 +19,15 @@ namespace Avalonia.Controls.Primitives
         /// Gets the size of the viewport, in logical units.
         /// </summary>
         Size Viewport { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        bool CanHorizontallyScroll { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        bool CanVerticallyScroll { get; }
     }
 }

src/Avalonia.Base/Input/Navigation/XYFocus.FindElements.cs

@@ -78,7 +78,7 @@ public partial class XYFocus
             return false;
         }
 
-        var closestScroller = candidate.FindAncestorOfType<IInternalScroller>(true);
+        var closestScroller = candidate.FindAncestorOfType<IScrollable>(true);
         return ReferenceEquals(closestScroller, activeScroller);
     }
 
@@ -93,7 +93,7 @@ public partial class XYFocus
         var parent = activeScroller.Parent;
         while (parent != null)
         {
-            if (parent is IInternalScroller and Visual visual
+            if (parent is IScrollable and Visual visual
                 && visual.IsVisualAncestorOf(candidate))
             {
                 return true;

src/Avalonia.Base/Input/Navigation/XYFocus.Impl.cs

@@ -415,7 +415,7 @@ public partial class XYFocus
         while (parent != null)
         {
             var element = parent;
-            if (element is IInternalScroller scrollable)
+            if (element is IScrollable scrollable)
             {
                 var isHorizontallyScrollable = scrollable.CanHorizontallyScroll;
                 var isVerticallyScrollable = scrollable.CanVerticallyScroll;

src/Avalonia.Controls/Presenters/ItemsPresenter.cs

@@ -45,35 +45,35 @@ namespace Avalonia.Controls.Presenters
         /// Gets the owner <see cref="ItemsControl"/>.
         /// </summary>
         internal ItemsControl? ItemsControl { get; private set; }
+
+        private bool CanHorizontallyScroll
+            => _logicalScrollable?.CanHorizontallyScroll ?? false;
         
-        bool ILogicalScrollable.CanHorizontallyScroll 
+        bool ILogicalScrollable.CanHorizontallyScroll
         {
-            get => _logicalScrollable?.CanHorizontallyScroll ?? false;
-            set
-            {
-                if (_logicalScrollable is not null)
-                    _logicalScrollable.CanHorizontallyScroll = value;
-            }
+            get => CanHorizontallyScroll;
+            set => _logicalScrollable?.CanHorizontallyScroll = value;
         }
 
-        bool ILogicalScrollable.CanVerticallyScroll 
+        bool IScrollable.CanHorizontallyScroll
+            => CanHorizontallyScroll;
+
+        private bool CanVerticallyScroll
+            => _logicalScrollable?.CanVerticallyScroll ?? false;
+
+        bool ILogicalScrollable.CanVerticallyScroll
         {
-            get => _logicalScrollable?.CanVerticallyScroll ?? false;
-            set
-            {
-                if (_logicalScrollable is not null)
-                    _logicalScrollable.CanVerticallyScroll = value;
-            }
+            get => CanVerticallyScroll;
+            set => _logicalScrollable?.CanVerticallyScroll = value;
         }
 
+        bool IScrollable.CanVerticallyScroll
+            => CanVerticallyScroll;
+
         Vector IScrollable.Offset 
         {
             get => _logicalScrollable?.Offset ?? default;
-            set
-            {
-                if (_logicalScrollable is not null)
-                    _logicalScrollable.Offset = value;
-            }
+            set => _logicalScrollable?.Offset = value;
         }
 
         bool ILogicalScrollable.IsLogicalScrollEnabled => _logicalScrollable?.IsLogicalScrollEnabled ?? false;

src/Avalonia.Controls/Primitives/ILogicalScrollable.cs

@@ -19,12 +19,12 @@ namespace Avalonia.Controls.Primitives
         /// <summary>
         /// Gets or sets a value indicating whether the content can be scrolled horizontally.
         /// </summary>
-        bool CanHorizontallyScroll { get; set; }
+        new bool CanHorizontallyScroll { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether the content can be scrolled horizontally.
         /// </summary>
-        bool CanVerticallyScroll { get; set; }
+        new bool CanVerticallyScroll { get; set; }
 
         /// <summary>
         /// Gets a value indicating whether logical scrolling is enabled on the control.

src/Avalonia.Controls/ScrollViewer.cs

@@ -14,7 +14,7 @@ namespace Avalonia.Controls
     /// </summary>
     [TemplatePart("PART_HorizontalScrollBar", typeof(ScrollBar))]
     [TemplatePart("PART_VerticalScrollBar",   typeof(ScrollBar))]
-    public class ScrollViewer : ContentControl, IScrollable, IScrollAnchorProvider, IInternalScroller
+    public class ScrollViewer : ContentControl, IScrollable, IScrollAnchorProvider
     {
         /// <summary>
         /// Defines the <see cref="BringIntoViewOnFocusChange "/> property.
@@ -284,7 +284,7 @@ namespace Avalonia.Controls
             get => HorizontalScrollBarVisibility != ScrollBarVisibility.Disabled;
         }
 
-        bool IInternalScroller.CanHorizontallyScroll => CanHorizontallyScroll;
+        bool IScrollable.CanHorizontallyScroll => CanHorizontallyScroll;
 
         /// <summary>
         /// Gets a value indicating whether the viewer can scroll vertically.
@@ -294,7 +294,7 @@ namespace Avalonia.Controls
             get => VerticalScrollBarVisibility != ScrollBarVisibility.Disabled;
         }
 
-        bool IInternalScroller.CanVerticallyScroll => CanVerticallyScroll;
+        bool IScrollable.CanVerticallyScroll => CanVerticallyScroll;
 
         /// <inheritdoc/>
         public Control? CurrentAnchor => (Presenter as IScrollAnchorProvider)?.CurrentAnchor;

src/Avalonia.Controls/VirtualizingCarouselPanel.cs

@@ -29,9 +29,23 @@ namespace Avalonia.Controls
         private int _transitionFromIndex = -1;
         private CancellationTokenSource? _transition;
         private EventHandler? _scrollInvalidated;
+        private bool _canHorizontallyScroll;
+        private bool _canVerticallyScroll;
 
-        bool ILogicalScrollable.CanHorizontallyScroll { get; set; }
-        bool ILogicalScrollable.CanVerticallyScroll { get; set; }
+        bool ILogicalScrollable.CanHorizontallyScroll
+        {
+            get => _canHorizontallyScroll;
+            set => _canHorizontallyScroll = value;
+        }
+
+        bool ILogicalScrollable.CanVerticallyScroll
+        {
+            get => _canVerticallyScroll;
+            set => _canVerticallyScroll = value;
+        }
+
+        bool IScrollable.CanHorizontallyScroll => _canHorizontallyScroll;
+        bool IScrollable.CanVerticallyScroll => _canVerticallyScroll;
         bool ILogicalScrollable.IsLogicalScrollEnabled => true;
         Size ILogicalScrollable.ScrollSize => new(1, 1);
         Size ILogicalScrollable.PageScrollSize => new(1, 1);