Merge pull request #5951 from unoplatform/dev/dr/wasmNativeSB

fix(scrollviewer): [WASM] Vertical native scrollbar could appears
unoplatform · May 7, 2021 · 534d3ba · 534d3ba
2 parents aca1a3a + dc33b68
commit 534d3ba
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Showing 2 changed files with 13 additions and 12 deletions.
diff --git a/src/Uno.UI/UI/Xaml/Controls/ScrollContentPresenter/ScrollContentPresenter.wasm.cs b/src/Uno.UI/UI/Xaml/Controls/ScrollContentPresenter/ScrollContentPresenter.wasm.cs
@@ -18,7 +18,7 @@ namespace Windows.UI.Xaml.Controls
 	public partial class ScrollContentPresenter : ContentPresenter, IScrollContentPresenter
 	{
 		private ScrollBarVisibility _verticalScrollBarVisibility;
-		private ScrollBarVisibility _horizotalScrollBarVisibility;
+		private ScrollBarVisibility _horizontalScrollBarVisibility;
 
 		internal Size ScrollBarSize
 		{
@@ -98,7 +98,7 @@ private void HandlePointerEvent(Input.PointerRoutedEventArgs e)
 		ScrollBarVisibility IScrollContentPresenter.VerticalScrollBarVisibility { get => VerticalScrollBarVisibility; set => VerticalScrollBarVisibility = value; }
 		internal ScrollBarVisibility VerticalScrollBarVisibility
 		{
-			get { return _verticalScrollBarVisibility; }
+			get => _verticalScrollBarVisibility;
 			set
 			{
 				if (_verticalScrollBarVisibility != value)
@@ -113,12 +113,12 @@ internal ScrollBarVisibility VerticalScrollBarVisibility
 		ScrollBarVisibility IScrollContentPresenter.HorizontalScrollBarVisibility { get => HorizontalScrollBarVisibility; set => HorizontalScrollBarVisibility = value; }
 		internal ScrollBarVisibility HorizontalScrollBarVisibility
 		{
-			get { return _horizotalScrollBarVisibility; }
+			get => _horizontalScrollBarVisibility;
 			set
 			{
-				if (_horizotalScrollBarVisibility != value)
+				if (_horizontalScrollBarVisibility != value)
 				{
-					_horizotalScrollBarVisibility = value;
+					_horizontalScrollBarVisibility = value;
 					SetClasses(HorizontalVisibilityClasses, (int)value);
 				}
 			}

diff --git a/src/Uno.UI/UI/Xaml/Controls/ScrollViewer/ScrollViewer.cs b/src/Uno.UI/UI/Xaml/Controls/ScrollViewer/ScrollViewer.cs
@@ -761,7 +761,7 @@ private void UpdateComputedVerticalScrollability(bool invalidate)
 
 #if !UNO_HAS_MANAGED_SCROLL_PRESENTER
 			// Support for the native scroll bars (delegated to the native _presenter).
-			_presenter.VerticalScrollBarVisibility = ComputeNativeScrollBarVisibility(visibility, mode, _verticalScrollbar);
+			_presenter.VerticalScrollBarVisibility = ComputeNativeScrollBarVisibility(scrollable, visibility, mode, _verticalScrollbar);
 			if (invalidate && _verticalScrollbar is null)
 			{
 				InvalidateMeasure(); // Useless for managed ScrollBar, it will invalidate itself if needed.
@@ -798,7 +798,7 @@ private void UpdateComputedHorizontalScrollability(bool invalidate)
 
 #if !UNO_HAS_MANAGED_SCROLL_PRESENTER
 			// Support for the native scroll bars (delegated to the native _presenter).
-			_presenter.HorizontalScrollBarVisibility = ComputeNativeScrollBarVisibility(visibility, mode, _horizontalScrollbar);
+			_presenter.HorizontalScrollBarVisibility = ComputeNativeScrollBarVisibility(scrollable, visibility, mode, _horizontalScrollbar);
 			if (invalidate && _horizontalScrollbar is null)
 			{
 				InvalidateMeasure(); // Useless for managed ScrollBar, it will invalidate itself if needed.
@@ -835,12 +835,13 @@ private static bool ComputeIsScrollEnabled(double scrollable, ScrollBarVisibilit
 				&& visibility != ScrollBarVisibility.Disabled
 				&& mode != ScrollMode.Disabled;
 
-		private ScrollBarVisibility ComputeNativeScrollBarVisibility(ScrollBarVisibility visibility, ScrollMode mode, ScrollBar? managedScrollbar)
-			=> mode switch
+		private ScrollBarVisibility ComputeNativeScrollBarVisibility(double scrollable, ScrollBarVisibility visibility, ScrollMode mode, ScrollBar? managedScrollbar)
+			=> (scrollable, visibility, mode, managedScrollbar) switch
 			{
-				ScrollMode.Disabled => ScrollBarVisibility.Disabled,
-				_ when managedScrollbar is null && Uno.UI.Xaml.Controls.ScrollViewer.GetShouldFallBackToNativeScrollBars(this) => visibility,
-				_ when visibility == ScrollBarVisibility.Disabled => ScrollBarVisibility.Disabled,
+				(_, _, ScrollMode.Disabled, _) => ScrollBarVisibility.Disabled,
+				(0, ScrollBarVisibility.Auto, _, null) => ScrollBarVisibility.Hidden, // If scrollable is 0, the managed scrollbar won't be realized, we prefer to hide the native one until we are sure!
+				(_, _, _, null) when Uno.UI.Xaml.Controls.ScrollViewer.GetShouldFallBackToNativeScrollBars(this) => visibility,
+				(_, ScrollBarVisibility.Disabled, _, _) => ScrollBarVisibility.Disabled,
 				_ => ScrollBarVisibility.Hidden // If a managed scroll bar was set in the template, native scroll bar has to stay Hidden
 			};