[cairo] painting a source to coordinates on a surface

[Norbert Fabritius]

Hello everyone,

I loaded an image as a source for a cairo-context, and now I wonder how I
can paint that source to some coordinates on the surface of the context.

context.paint() does the job, but doesn't accept coordinates. I find it
very hard to find good documentation on all the cairo principles, like
transforming and translating, which may solve my problem.