dx,dy) by matrix. This is
similar to cairoMatrixTransformPoint except that the translation
components of the transformation are ignored. The calculation of
the returned vector is as follows:cairoMatrixTransformDistance(matrix, dx, dy)matrixdxdydx2 = dx1 * a + dy1 * c; dy2 = dx1 * b + dy1 * d;Affine transformations are position invariant, so the same vector always transforms to the same vector. If (
x1,y1) transforms
to (x2,y2) then (x1+dx1,y1+dy1) will transform to
(x1+dx2,y1+dy2) for all values of x1 and x2.