[cairo] Position a pattern at the tip of a rectangle

[thomas at tgohome.com]

I have a pattern which starts at (0,0) and ends at (1,1). I scale it by a
factor of 200x, to get a pattern from (0,0) to (200,200). Now, I want to
create a rectangle which exists from, say (300,300) to (500,500), and draw
the pattern as if it started at the top left of the rectangle. How can
this be done?

Thanks, Tom