Scaled Blits only through transformation matrix?

[Clemens Eisserer]

Hello,

I have to create a routine for scaled blits which looks like this:
scaledBlit(source, destination, int sx1, int sy1, int sx2, int sy2,
double dx1, double dy1, double dx2, double dy2)
The the user specifies a rectangle in the source and a rectangle in
the destination, and the library scales the source according to the
proportion of the two rectangles.

As far as I have seen XRender is only capable of repeating if the
destination rectangle is larger than the source, or am I wrong?
Is the only way to serve a request like above to modify the
tranformation-matrix of the destination?

Thank you in advance, lg Clemens