[Shapes] Fix RectTypeConverter

Xamarin.Forms.Core/RectTypeConverter.cs

@@ -1,14 +1,25 @@
-namespace Xamarin.Forms
+using System;
+using System.Globalization;
+
+namespace Xamarin.Forms
 {
 	[Xaml.TypeConversion(typeof(Rect))]
-	public class RectTypeConverter : RectangleTypeConverter
+	public class RectTypeConverter : TypeConverter
 	{
 		public override object ConvertFromInvariantString(string value)
 		{
-			var rectangle = base.ConvertFromInvariantString(value);
-			Rect rect = (Rectangle)rectangle;
+			if (value != null)
+			{
+				string[] xywh = value.Split(',');
+				if (xywh.Length == 4
+					&& double.TryParse(xywh[0], NumberStyles.Number, CultureInfo.InvariantCulture, out double x)
+					&& double.TryParse(xywh[1], NumberStyles.Number, CultureInfo.InvariantCulture, out double y)
+					&& double.TryParse(xywh[2], NumberStyles.Number, CultureInfo.InvariantCulture, out double w)
+					&& double.TryParse(xywh[3], NumberStyles.Number, CultureInfo.InvariantCulture, out double h))
+					return new Rect(x, y, w, h);
+			}
 
-			return rect;
+			throw new InvalidOperationException(string.Format("Cannot convert \"{0}\" into {1}", value, typeof(Rect)));
 		}
 	}
 }

Xamarin.Forms.Xaml.UnitTests/Issues/Gh11541.xaml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage
+        xmlns="http://xamarin.com/schemas/2014/forms"
+        xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+        x:Class="Xamarin.Forms.Xaml.UnitTests.Gh11541">
+    <Image Source="monkeyface.png">
+	<Image.Clip>
+	    <RectangleGeometry Rect="40,100,300,150" />
+        </Image.Clip>
+    </Image>
+</ContentPage>

Xamarin.Forms.Xaml.UnitTests/Issues/Gh11541.xaml.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+
+using Xamarin.Forms;
+using Xamarin.Forms.Core.UnitTests;
+
+using NUnit.Framework;
+
+namespace Xamarin.Forms.Xaml.UnitTests
+{
+	public partial class Gh11541 : ContentPage
+	{
+		public Gh11541() => InitializeComponent();
+		public Gh11541(bool useCompiledXaml)
+		{
+			//this stub will be replaced at compile time
+		}
+
+		[TestFixture]
+		class Tests
+		{
+			[SetUp] public void Setup() => Device.PlatformServices = new MockPlatformServices();
+
+			[TearDown] public void TearDown() => Device.PlatformServices = null;
+
+			[Test]
+			public void RectangleGeometryDoesntThrow([Values(false, true)] bool useCompiledXaml)
+			{
+				var layout = new Gh11541(useCompiledXaml);
+			}
+		}
+	}
+}