[Android] Fixed the ScrollbarVisibility issues (#27613)

* [Android] Fixed the ScrollbarVisibility issues

* Committed the review changes and added additional test

* Renamed Variable

Author: Ahamed-Ali

src/Core/src/Platform/Android/MauiScrollView.cs

@@ -63,19 +63,23 @@ public void SetHorizontalScrollBarVisibility(ScrollBarVisibility scrollBarVisibi
 			}
 
 			_hScrollView.HorizontalScrollBarEnabled = scrollBarVisibility == ScrollBarVisibility.Always;
+			_hScrollView.ScrollbarFadingEnabled = _horizontalScrollVisibility != ScrollBarVisibility.Always;
+			PlatformInterop.RequestLayoutIfNeeded(this);
 		}
 
 		public void SetVerticalScrollBarVisibility(ScrollBarVisibility scrollBarVisibility)
 		{
+			ScrollBarVisibility verticalScrollVisibility = scrollBarVisibility;
+
 			if (_defaultVerticalScrollVisibility == 0)
 				_defaultVerticalScrollVisibility = VerticalScrollBarEnabled ? ScrollBarVisibility.Always : ScrollBarVisibility.Never;
 
 			if (scrollBarVisibility == ScrollBarVisibility.Default)
 				scrollBarVisibility = _defaultVerticalScrollVisibility;
 
 			VerticalScrollBarEnabled = scrollBarVisibility == ScrollBarVisibility.Always;
-
-			this.HandleScrollBarVisibilityChange();
+			ScrollbarFadingEnabled = verticalScrollVisibility != ScrollBarVisibility.Always;
+			PlatformInterop.RequestLayoutIfNeeded(this);
 		}
 
 		public void SetContent(View content)
@@ -428,7 +432,6 @@ public override bool HorizontalScrollBarEnabled
 			set
 			{
 				base.HorizontalScrollBarEnabled = value;
-				this.HandleScrollBarVisibilityChange();
 			}
 		}
 

src/Core/tests/DeviceTests/Handlers/ScrollView/ScrollViewHandlerTests.Android.cs

@@ -102,6 +102,76 @@ public async Task VerticalVisibilityInitializesCorrectly(ScrollBarVisibility vis
 			Assert.Equal(expected, result);
 		}
 
+		[Theory]
+		[InlineData(ScrollBarVisibility.Always, false)]
+		[InlineData(ScrollBarVisibility.Default, true)]
+		[InlineData(ScrollBarVisibility.Never, true)]
+		public async Task VerticalScrollbarFadingInitializesCorrectly(ScrollBarVisibility visibility, bool expected)
+		{
+			bool result = await InvokeOnMainThreadAsync(() =>
+			{
+				var scrollView = new ScrollViewStub()
+				{
+					Orientation = ScrollOrientation.Vertical,
+					VerticalScrollBarVisibility = visibility
+				};
+
+				var scrollViewHandler = CreateHandler(scrollView);
+
+				return ((MauiScrollView)scrollViewHandler.PlatformView).ScrollbarFadingEnabled;
+			});
+
+			Assert.Equal(expected, result);
+		}
+
+		[Theory]
+		[InlineData(ScrollBarVisibility.Always, false)]
+		[InlineData(ScrollBarVisibility.Default, true)]
+		[InlineData(ScrollBarVisibility.Never, true)]
+		public async Task HorizontalScrollbarFadingInitializesCorrectly(ScrollBarVisibility visibility, bool expected)
+		{
+			bool result = await InvokeOnMainThreadAsync(() =>
+			{
+				var scrollView = new ScrollViewStub()
+				{
+					Orientation = ScrollOrientation.Horizontal,
+					HorizontalScrollBarVisibility = visibility
+				};
+
+				var scrollViewHandler = CreateHandler(scrollView);
+
+				return ((MauiHorizontalScrollView)scrollViewHandler.PlatformView.GetChildAt(0)).ScrollbarFadingEnabled;
+			});
+
+			Assert.Equal(expected, result);
+		}
+
+		[Theory]
+		[InlineData(ScrollBarVisibility.Always, false)]
+		[InlineData(ScrollBarVisibility.Default, true)]
+		[InlineData(ScrollBarVisibility.Never, true)]
+		public async Task VerticalandHorizontalScrollbarFadingInitializesCorrectlyOnBothOrientation(ScrollBarVisibility visibility, bool expected)
+		{
+			bool result = await InvokeOnMainThreadAsync(() =>
+			{
+				var scrollView = new ScrollViewStub()
+				{
+					Orientation = ScrollOrientation.Both,
+					HorizontalScrollBarVisibility = visibility,
+					VerticalScrollBarVisibility = visibility
+				};
+
+				var scrollViewHandler = CreateHandler(scrollView);
+
+				var horizontalScrollView = (MauiHorizontalScrollView)scrollViewHandler.PlatformView.GetChildAt(0);
+				var verticalScrollView = (MauiScrollView)scrollViewHandler.PlatformView;
+
+				return horizontalScrollView.ScrollbarFadingEnabled && verticalScrollView.ScrollbarFadingEnabled;
+			});
+
+			Assert.Equal(expected, result);
+		}
+
 		[Fact]
 		public async Task MauiScrollViewGetsFullHeightInHorizontalOrientation()
 		{