Fixed issue creating Paths with segments without points on iOS (#13161)

Co-authored-by: Gerald Versluis <gerald.versluis@microsoft.com>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue13159.cs

@@ -0,0 +1,126 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using Xamarin.Forms.Shapes;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+using Xamarin.Forms.Core.UITests;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 13159, "[Bug] +Fix. Path.Data crashing when geometry has a PolyLineSegment with 0 point",
+		PlatformAffected.iOS)]
+#if UITEST
+	[Category(UITestCategories.Shape)]
+#endif
+	public class Issue13159 : TestContentPage
+	{
+		const string TestReady = "TestReadyId";
+
+		public Issue13159()
+		{
+
+		}
+
+		protected override void Init()
+		{
+			var layout = new StackLayout();
+
+			var instructions = new Label
+			{
+				AutomationId = TestReady,
+				Padding = 12,
+				BackgroundColor = Color.Black,
+				TextColor = Color.White,
+				Text = "Without exceptions, the test has passed."
+			};
+
+			layout.Children.Add(instructions);
+			layout.Children.Add(CreateNoPointsPolyLineSegmentPath());
+			layout.Children.Add(CreateNoPointsPolyBezierSegmentPath());
+			layout.Children.Add(CreateNoPointsPolyQuadraticBezierSegmentPath());
+			layout.Children.Add(CreateNoPointsArcSegmentPath());
+
+			Content = layout;
+		}
+
+		Path CreateNoPointsPolyLineSegmentPath()
+		{
+			var path = new Path();
+
+			PathFigure pathFigure = new PathFigure();
+
+			pathFigure.Segments.Add(new PolyLineSegment());
+
+			PathGeometry geometry = new PathGeometry();
+
+			geometry.Figures.Add(pathFigure);
+
+			path.Data = geometry;
+
+			return path;
+		}
+
+		Path CreateNoPointsPolyBezierSegmentPath()
+		{
+			var path = new Path();
+
+			PathFigure pathFigure = new PathFigure();
+
+			pathFigure.Segments.Add(new PolyBezierSegment());
+
+			PathGeometry geometry = new PathGeometry();
+
+			geometry.Figures.Add(pathFigure);
+
+			path.Data = geometry;
+
+			return path;
+		}
+
+		Path CreateNoPointsPolyQuadraticBezierSegmentPath()
+		{
+			var path = new Path();
+
+			PathFigure pathFigure = new PathFigure();
+
+			pathFigure.Segments.Add(new PolyQuadraticBezierSegment());
+
+			PathGeometry geometry = new PathGeometry();
+
+			geometry.Figures.Add(pathFigure);
+
+			path.Data = geometry;
+
+			return path;
+		}
+
+		Path CreateNoPointsArcSegmentPath()
+		{
+			var path = new Path();
+
+			PathFigure pathFigure = new PathFigure();
+
+			pathFigure.Segments.Add(new ArcSegment());
+
+			PathGeometry geometry = new PathGeometry();
+
+			geometry.Figures.Add(pathFigure);
+
+			path.Data = geometry;
+
+			return path;
+		}
+
+#if UITEST && __IOS__
+		[Test]
+		public void Issue13159NoPointsPathTest()
+		{
+			RunningApp.WaitForElement(TestReady);
+		}
+#endif
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -1794,6 +1794,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue8833.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10086.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13136.xaml.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue13159.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11980.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13173.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8282.xaml.cs" />

Xamarin.Forms.Platform.iOS/Extensions/GeometryExtensions.cs

@@ -90,7 +90,7 @@ public static PathData ToCGPath(this Geometry geometry, Transform renderTransfor
                             for (int i = 0; i < points.Count; i++)
                                 pathData.Data.AddLineToPoint(transform, points[i].ToPointF());
 
-                            lastPoint = points[points.Count - 1];
+                            lastPoint = points.Count > 0 ? points[points.Count - 1] : Point.Zero;
                         }
                         // BezierSegment
                         else if (pathSegment is BezierSegment)
@@ -123,7 +123,7 @@ public static PathData ToCGPath(this Geometry geometry, Transform renderTransfor
                                 }
                             }
 
-                            lastPoint = points[points.Count - 1];
+                            lastPoint = points.Count > 0 ? points[points.Count - 1] : Point.Zero;
                         }
                         // QuadraticBezierSegment
                         else if (pathSegment is QuadraticBezierSegment)
@@ -158,7 +158,7 @@ public static PathData ToCGPath(this Geometry geometry, Transform renderTransfor
                                 }
                             }
 
-                            lastPoint = points[points.Count - 1];
+                            lastPoint = points.Count > 0 ? points[points.Count - 1] : Point.Zero;
                         }
                         // ArcSegment
                         else if (pathSegment is ArcSegment)