Bitmap Potter / Clipping rectangle

Hello again ;) I have a question about the clipping rectangle within the bitmap plot function... Should the clipping rectangle clip the original image or should it clip the scaled image? Framebuffer version is not an good reference for this, because it doesn't implement scaling. GTK does it, but the code is gdk dependent and I'm not sure how these gdk_* functions behave. If the clipping really should be done on the source image, should the clipping rectangle also get scaled like the image, and then applied to the scaled image? Thanks for reading and your help. :) Greets, Ole