Fix tile mode used in SkShader for a TileBrush with None TileMode (#16021)

* add cross test for tile brush with None tile mode

* use Decal skshader tile mode for tile brush tilemode None

src/Skia/Avalonia.Skia/DrawingContextImpl.cs

@@ -1072,14 +1072,14 @@ namespace Avalonia.Skia
 
             SKShaderTileMode tileX =
                 tileBrush.TileMode == TileMode.None
-                    ? SKShaderTileMode.Clamp
+                    ? SKShaderTileMode.Decal
                     : tileBrush.TileMode == TileMode.FlipX || tileBrush.TileMode == TileMode.FlipXY
                         ? SKShaderTileMode.Mirror
                         : SKShaderTileMode.Repeat;
 
             SKShaderTileMode tileY =
                 tileBrush.TileMode == TileMode.None
-                    ? SKShaderTileMode.Clamp
+                    ? SKShaderTileMode.Decal
                     : tileBrush.TileMode == TileMode.FlipY || tileBrush.TileMode == TileMode.FlipXY
                         ? SKShaderTileMode.Mirror
                         : SKShaderTileMode.Repeat;
@@ -1225,14 +1225,14 @@ namespace Avalonia.Skia
 
             SKShaderTileMode tileX =
                 tileBrush.TileMode == TileMode.None
-                    ? SKShaderTileMode.Clamp
+                    ? SKShaderTileMode.Decal
                     : tileBrush.TileMode == TileMode.FlipX || tileBrush.TileMode == TileMode.FlipXY
                         ? SKShaderTileMode.Mirror
                         : SKShaderTileMode.Repeat;
 
             SKShaderTileMode tileY =
                 tileBrush.TileMode == TileMode.None
-                    ? SKShaderTileMode.Clamp
+                    ? SKShaderTileMode.Decal
                     : tileBrush.TileMode == TileMode.FlipY || tileBrush.TileMode == TileMode.FlipXY
                         ? SKShaderTileMode.Mirror
                         : SKShaderTileMode.Repeat;

tests/Avalonia.RenderTests/CrossTests/Brushes/CrossTileBrushTests.cs

@@ -108,6 +108,38 @@ public class CrossTileBrushTests : CrossTestBase
 
     }
 
+    [CrossFact]
+    public void Should_Render_TileBrush_With_TileMode_None()
+    {
+        var brush = new CrossDrawingBrush
+        {
+            TileMode = TileMode.None,
+            Stretch = Stretch.Fill,
+            Viewbox = new Rect(0, 0, 50, 50),
+            ViewboxUnits = BrushMappingMode.Absolute,
+            Viewport = new Rect(0, 0, 50, 50),
+            ViewportUnits = BrushMappingMode.Absolute,
+            Drawing = new CrossDrawingGroup()
+            {
+                Children = new List<CrossDrawing>()
+                {
+                    new CrossGeometryDrawing(new CrossRectangleGeometry(new(0, 0, 50, 50)))
+                    {
+                        Brush = new CrossSolidColorBrush(Colors.Crimson)
+                    },
+                }
+            }
+        };
+
+        RenderAndCompare(new CrossControl()
+        {
+            Width = 200,
+            Height = 200,
+            Background = brush
+        });
+
+    }
+
     [CrossFact]
     public void Should_Render_With_Transform()
     {