fix: adjust frame coords for LayoutSlot in ListView/GridView

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_GridView_Items.cs

@@ -0,0 +1,78 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Uno.UI.RuntimeTests.Helpers;
+using Windows.Foundation;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Controls.Primitives;
+using static Private.Infrastructure.TestServices;
+
+namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls
+{
+#if HAS_UNO
+	[TestClass]
+	[RunsOnUIThread]
+#if !__IOS__
+	[Ignore]
+#endif
+	public class Given_GridView_Items
+	{
+		[TestMethod]
+		public async Task When_GridViewItems_LayoutSlots()
+		{
+			var gridView = new GridView
+			{
+				ItemContainerStyle = TestsResourceHelper.GetResource<Style>("MyGridViewItemStyle")
+			};
+
+			var gvi = new GridViewItem();
+			var gvi2 = new GridViewItem();
+
+			gridView.ItemsSource = new[] { gvi, gvi2 };
+
+			WindowHelper.WindowContent = gridView;
+			await WindowHelper.WaitForLoaded(gridView);
+			await WindowHelper.WaitForIdle();
+
+			RectAssert.AreEqual(new Rect
+			{
+				X = 0d,
+				Y = 0d,
+				Width = 104d,
+				Height = 104d,
+			},
+			gvi.LayoutSlot);
+
+			RectAssert.AreEqual(new Rect
+			{
+				X = 0d,
+				Y = 0d,
+				Width = 100d,
+				Height = 100d,
+			},
+			gvi.LayoutSlotWithMarginsAndAlignments);
+
+			RectAssert.AreEqual(new Rect
+			{
+				X = 104d,
+				Y = 0d,
+				Width = 104d,
+				Height = 104d,
+			},
+			gvi2.LayoutSlot);
+
+			RectAssert.AreEqual(new Rect
+			{
+				X = 104d,
+				Y = 0d,
+				Width = 100d,
+				Height = 100d,
+			},
+			gvi2.LayoutSlotWithMarginsAndAlignments);
+		}
+	}
+#endif
+}

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/TestsResources.xaml

@@ -267,4 +267,30 @@
 					   HorizontalAlignment="Center" />
 		</Border>
 	</DataTemplate>
+
+	<Style x:Key="MyGridViewItemStyle"
+               TargetType="GridViewItem">
+		<Setter Property="Background" Value="Transparent" />
+		<Setter Property="TabNavigation" Value="Local" />
+		<Setter Property="IsHoldingEnabled" Value="True" />
+		<Setter Property="HorizontalContentAlignment" Value="Center" />
+		<Setter Property="VerticalContentAlignment" Value="Center" />
+		<Setter Property="MinWidth" Value="0" />
+		<Setter Property="MinHeight" Value="0" />
+		<Setter Property="Template">
+			<Setter.Value>
+				<ControlTemplate TargetType="GridViewItem">
+					<Grid x:Name="ContentBorder">
+						<Rectangle x:Name="BorderRectangle"
+                                       Width="100"
+                                       Height="100"
+                                       IsHitTestVisible="False"
+                                       Fill="Green"
+                                       Stroke="Red"
+                                       StrokeThickness="2" />
+					</Grid>
+				</ControlTemplate>
+			</Setter.Value>
+		</Setter>
+	</Style>
 </ResourceDictionary>

src/Uno.UI/UI/Xaml/Controls/ListViewBase/ListViewBaseSource.iOS.cs

@@ -755,7 +755,6 @@ public override CGRect Frame
 			{
 				base.Frame = value;
 				UpdateContentViewFrame();
-				UpdateContentLayoutSlots(value);
 			}
 		}
 
@@ -772,7 +771,6 @@ public override CGRect Bounds
 				}
 				base.Bounds = value;
 				UpdateContentViewFrame();
-				UpdateContentLayoutSlots(Frame);
 			}
 		}
 
@@ -797,8 +795,19 @@ private void UpdateContentLayoutSlots(Rect frame)
 			var content = Content;
 			if (content != null)
 			{
-				LayoutInformation.SetLayoutSlot(content, frame);
-				content.LayoutSlotWithMarginsAndAlignments = frame;
+				var layoutSlot = LayoutInformation.GetLayoutSlot(content);
+				var layoutSlotWithMarginsAndAlignments = content.LayoutSlotWithMarginsAndAlignments;
+
+				//The LayoutInformation within ArrangeChild does not take into account the offset relative to the native ListView, so we apply that offset here.
+				//This is needed for TransformToVisual to work
+				layoutSlot.X = frame.X;
+				layoutSlot.Y = frame.Y;
+
+				layoutSlotWithMarginsAndAlignments.X += frame.X;
+				layoutSlotWithMarginsAndAlignments.Y += frame.Y;
+
+				LayoutInformation.SetLayoutSlot(content, layoutSlot);
+				content.LayoutSlotWithMarginsAndAlignments = layoutSlotWithMarginsAndAlignments;
 			}
 		}