Manpages - FcMatrixRotate.3

FcMatrixRotate - Rotate a matrix

#include <fontconfig/fontconfig.h>

void FcMatrixRotate (FcMatrix matrix, double cos, double sin);*

FcMatrixRotate rotates matrix by the angle who’s sine is sin and cosine is cos. This is done by multiplying by the matrix:

    cos -sin
    sin  cos