[Cairo] New functions for cairo_matrix

[Carl Worth]

On Nov 14, Duncan Mak wrote:
 > I see that I can use get_affine to implement this.

Good.

 > By the way, here's the patch for cairo_matrix_equals.

Thanks.

After looking closer though, I've got some questions. I notice that
the patch does equality testing of floating-point numbers. Is that
really what you want? If so, wouldn't it basically be equivalent to
just compare the two cairo_matrix_t pointers?

Otherwise, I don't know of a good distance metric on the space of
affine matrices with floating-point values.

So what was it exactly you wanted again?

-Carl