Add a default template for the surfaces

Fixes #296

source/SkiaSharp.Extended.UI.Maui/Controls/SKSurfaceView.shared.cs

@@ -17,8 +17,10 @@ public class SKSurfaceView : TemplatedView
 	private SKCanvasView? canvasView;
 	private SKGLView? glView;
 
-	internal SKSurfaceView()
+	public SKSurfaceView()
 	{
+		ResourceLoader<Themes.SKSurfaceViewResources>.EnsureRegistered(this);
+
 		DebugUtils.LogPropertyChanged(this);
 	}
 

source/SkiaSharp.Extended.UI.Maui/Controls/SKSurfaceViewResources.shared.xaml

@@ -0,0 +1,23 @@
+<ResourceDictionary xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+                    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+                    xmlns:local="clr-namespace:SkiaSharp.Extended.UI.Controls"
+                    xmlns:skia="clr-namespace:SkiaSharp.Views.Maui.Controls;assembly=SkiaSharp.Views.Maui.Controls"
+                    x:Class="SkiaSharp.Extended.UI.Controls.Themes.SKSurfaceViewResources">
+
+    <!-- the control template for SKSurfaceView -->
+    <ControlTemplate x:Key="SKSurfaceViewControlTemplate">
+        <skia:SKCanvasView x:Name="PART_DrawingSurface" />
+    </ControlTemplate>
+
+    <!-- the explicit style that allows for extension -->
+    <Style x:Key="SKSurfaceViewStyle" TargetType="local:SKSurfaceView">
+        <Setter Property="ControlTemplate"
+                Value="{StaticResource SKSurfaceViewControlTemplate}" />
+    </Style>
+
+    <!-- the implicit style that applies to all controls -->
+    <Style TargetType="local:SKSurfaceView"
+           ApplyToDerivedTypes="True"
+           BasedOn="{StaticResource SKSurfaceViewStyle}" />
+
+</ResourceDictionary>

source/SkiaSharp.Extended.UI.Maui/Controls/SKSurfaceViewResources.shared.xaml.cs

@@ -0,0 +1,9 @@
+namespace SkiaSharp.Extended.UI.Controls.Themes;
+
+public partial class SKSurfaceViewResources : ResourceDictionary
+{
+	public SKSurfaceViewResources()
+	{
+		InitializeComponent();
+	}
+}