Clamp Grid coordinates for child views (#1947)

* Clamp Grid coordinates

* Use correct values

* bad coments

* Add span tests

src/Core/src/Layouts/GridLayoutManager.cs

@@ -159,8 +159,8 @@ void InitializeCells()
 						continue;
 					}
 
-					var column = _grid.GetColumn(view);
-					var columnSpan = _grid.GetColumnSpan(view);
+					var column = _grid.GetColumn(view).Clamp(0, _columns.Length - 1);
+					var columnSpan = _grid.GetColumnSpan(view).Clamp(1, _columns.Length - column);
 
 					var columnGridLengthType = GridLengthType.None;
 
@@ -169,8 +169,8 @@ void InitializeCells()
 						columnGridLengthType |= ToGridLengthType(_columns[columnIndex].ColumnDefinition.Width.GridUnitType);
 					}
 
-					var row = _grid.GetRow(view);
-					var rowSpan = _grid.GetRowSpan(view);
+					var row = _grid.GetRow(view).Clamp(0, _rows.Length - 1);
+					var rowSpan = _grid.GetRowSpan(view).Clamp(1, _rows.Length - row);
 
 					var rowGridLengthType = GridLengthType.None;
 
@@ -189,11 +189,11 @@ void InitializeCells()
 
 			public Rectangle GetCellBoundsFor(IView view)
 			{
-				var firstColumn = _grid.GetColumn(view);
-				var lastColumn = firstColumn + _grid.GetColumnSpan(view);
+				var firstColumn = _grid.GetColumn(view).Clamp(0, _columns.Length - 1);
+				var lastColumn = firstColumn + _grid.GetColumnSpan(view).Clamp(1, _columns.Length - firstColumn);
 
-				var firstRow = _grid.GetRow(view);
-				var lastRow = firstRow + _grid.GetRowSpan(view);
+				var firstRow = _grid.GetRow(view).Clamp(0, _rows.Length - 1);
+				var lastRow = firstRow + _grid.GetRowSpan(view).Clamp(1, _rows.Length - firstRow);
 
 				double top = TopEdgeOfRow(firstRow);
 				double left = LeftEdgeOfColumn(firstColumn);

src/Core/tests/UnitTests/Layouts/GridLayoutManagerTests.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using Microsoft.Maui.Controls;
 using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Layouts;
@@ -1240,5 +1241,91 @@ public void GridMeasureShouldUseExplicitWidth()
 
 			Assert.Equal(50, measure.Width);
 		}
+
+		[Theory]
+		// at 0, 0
+		[InlineData(1, 1, 0, 0, 0, 0)]
+		[InlineData(1, 2, 0, 0, 0, 0)]
+		[InlineData(2, 1, 0, 0, 0, 0)]
+		[InlineData(2, 2, 0, 0, 0, 0)]
+		// at 1, 0
+		[InlineData(1, 1, 1, 0, 0, 0)]
+		[InlineData(1, 2, 1, 0, 0, 0)]
+		[InlineData(2, 1, 1, 0, 1, 0)]
+		[InlineData(2, 2, 1, 0, 1, 0)]
+		// at 0, 1
+		[InlineData(1, 1, 0, 1, 0, 0)]
+		[InlineData(1, 2, 0, 1, 0, 1)]
+		[InlineData(2, 1, 0, 1, 0, 0)]
+		[InlineData(2, 2, 0, 1, 0, 1)]
+		// at 1, 1
+		[InlineData(1, 1, 1, 1, 0, 0)]
+		[InlineData(1, 2, 1, 1, 0, 1)]
+		[InlineData(2, 1, 1, 1, 1, 0)]
+		[InlineData(2, 2, 1, 1, 1, 1)]
+		public void ViewOutsideRowsAndColsClampsToGrid(int rows, int cols, int row, int col, int actualRow, int actualCol)
+		{
+			var r = string.Join(",", Enumerable.Repeat("100", rows));
+			var c = string.Join(",", Enumerable.Repeat("100", cols));
+
+			var grid = CreateGridLayout(rows: r, columns: c);
+			var view0 = CreateTestView(new Size(10, 10));
+			SubstituteChildren(grid, view0);
+			SetLocation(grid, view0, row, col);
+
+			MeasureAndArrange(grid, 100 * cols, 100 * rows);
+
+			AssertArranged(view0, 100 * actualCol, 100 * actualRow, 100, 100);
+		}
+
+		[Theory]
+		// normal
+		[InlineData(0, 0, 1, 1, 0, 0, 1, 1)]
+		[InlineData(1, 1, 1, 1, 1, 1, 1, 1)]
+		[InlineData(1, 1, 2, 1, 1, 1, 2, 1)]
+		// negative origin
+		[InlineData(-1, 0, 1, 1, 0, 0, 1, 1)]
+		[InlineData(0, -1, 1, 1, 0, 0, 1, 1)]
+		[InlineData(-1, -1, 1, 1, 0, 0, 1, 1)]
+		// negative span
+		[InlineData(1, 1, -1, 0, 1, 1, 1, 1)]
+		[InlineData(1, 1, 0, -1, 1, 1, 1, 1)]
+		[InlineData(1, 1, -1, -1, 1, 1, 1, 1)]
+		// positive origin
+		[InlineData(5, 0, 1, 1, 3, 0, 1, 1)]
+		[InlineData(0, 5, 1, 1, 0, 3, 1, 1)]
+		[InlineData(5, 5, 1, 1, 3, 3, 1, 1)]
+		// positive span
+		[InlineData(0, 0, 1, 5, 0, 0, 1, 4)]
+		[InlineData(0, 0, 5, 1, 0, 0, 4, 1)]
+		[InlineData(0, 0, 5, 5, 0, 0, 4, 4)]
+		// normal origin + positive span
+		[InlineData(1, 1, 1, 5, 1, 1, 1, 3)]
+		[InlineData(1, 1, 5, 1, 1, 1, 3, 1)]
+		[InlineData(1, 1, 5, 5, 1, 1, 3, 3)]
+		// positive origin + positive span
+		[InlineData(5, 5, 1, 5, 3, 3, 1, 1)]
+		[InlineData(5, 5, 5, 1, 3, 3, 1, 1)]
+		[InlineData(5, 5, 5, 5, 3, 3, 1, 1)]
+		public void SpansOutsideRowsAndColsClampsToGrid(int row, int col, int rowSpan, int colSpan, int actualRow, int actualCol, int actualRowSpan, int actualColSpan)
+		{
+			const int GridSize = 4;
+			var r = string.Join(",", Enumerable.Repeat("100", GridSize));
+			var c = string.Join(",", Enumerable.Repeat("100", GridSize));
+
+			var grid = CreateGridLayout(rows: r, columns: c);
+			var view0 = CreateTestView(new Size(10, 10));
+			SubstituteChildren(grid, view0);
+			SetLocation(grid, view0, row, col, rowSpan, colSpan);
+
+			MeasureAndArrange(grid, 100 * GridSize, 100 * GridSize);
+
+			AssertArranged(
+				view0,
+				100 * actualCol,
+				100 * actualRow,
+				100 * actualColSpan,
+				100 * actualRowSpan);
+		}
 	}
 }