void DrawToImageSource(CanvasDrawingSession canvasControlDrawingSession)
{
// XAML doesn't support nested image source drawing sessions, so we must close
// the main CanvasControl one before drawing to a different CanvasImageSource.
canvasControlDrawingSession.Dispose();
using (var ds = imageSource.CreateDrawingSession(Colors.Transparent))
{
DrawToOutput(mainDeviceResources, ds);
}
}