static UIImage MakeEmpty ()
{
using (var cs = CGColorSpace.CreateDeviceRGB ()){
using (var bit = new CGBitmapContext (IntPtr.Zero, dimx, dimy, 8, 0, cs, CGImageAlphaInfo.PremultipliedFirst)){
bit.SetStrokeColor (1, 0, 0, 0.5f);
bit.FillRect (new RectangleF (0, 0, dimx, dimy));
return UIImage.FromImage (bit.ToImage ());
}
}
}
