Rectangle now have a IsStoke property.

Added math functions to ExecutionEngine.

Progrart.Core/PrimitiveDrawingCore.cs

@@ -0,0 +1,39 @@
+using Progrart.Core.Storage;
+using SkiaSharp;
+using System.Diagnostics;
+
+namespace Progrart.Core
+{
+    public class PrimitiveDrawingCore : IDisposable
+	{
+		internal bool isDisposed = false;
+		SKSurface surface;
+		SKImageInfo info;
+		public readonly int Width;
+		public readonly int Height;
+		public SKCanvas canvas { get; }
+		internal IStorageProvider StorageProvider;
+		public PrimitiveDrawingCore(int W, int H, IStorageProvider storageProvider)
+		{
+			Width = W;
+			Height = H;
+			Trace.WriteLine($"Createing Surface as: {W} x {H}");
+			info = new SKImageInfo(W, H);
+			surface = SKSurface.Create(info);
+			canvas = surface.Canvas;
+			canvas.Clear();
+			StorageProvider = storageProvider;
+		}
+		public SKData ToData()
+		{
+			return surface.Snapshot().Encode(SKEncodedImageFormat.Png, 100);
+		}
+		public void Dispose()
+		{
+			if (isDisposed) return;
+			//GC.SuppressFinalize(this);
+			isDisposed = true;
+			surface.Dispose();
+		}
+	}
+}