gistfile1.cs

public static Uri SaveTile(UserControl control, string filename, double width, double height)
{
  string path = tileFolder + filename + ".png";
  bool success = true;

  Deployment.Current.Dispatcher.BeginInvoke(() =>
  {
    control.Width = width;
    control.Height = height;
    control.Measure(new Size(width, height));
    control.Arrange(new Rect(0, 0, width, height));

    try
    {
      ExtendedImage tileImaged = control.ToImage();

      if (tileImaged == null || tileImaged.PixelWidth < 100)
      {
        success = false;
      }
      else
      {
        Encoders.AddEncoder<PngEncoder>();
        PngEncoder pngEncoder = new PngEncoder();

        using (var isf = IsolatedStorageFile.GetUserStoreForApplication())
        {
          using (var stream = isf.OpenFile(path, System.IO.FileMode.OpenOrCreate))
          {
            pngEncoder.Encode(tileImaged, stream);
            stream.Close();
            success = true;
          }
        }
      }
    }
    catch
    {
      success = false;
    }
  });

  if (success == false)
  {
    throw new PokiException("Tile could not be saved");
  }


  return new Uri("isostore:" + path, UriKind.Absolute);
}