Canvas.Render() clears the rest of the previous rendered image.

[Bastitron]

Hey!
What I want to do: Embed the generated QR-Code on my pre rendered canvas. The following line is the method I use to draw it on top of my Canvas.
SkSurface.Canvas.Render(qr, area: new SKRect(300, 300, 700, 700), SKColors.Transparent, SKColors.Black);
But instead it just clears everything and then draws on top of the canvas. Anyone an Idea how to disable this?