cairo_matrix_transform_distance

Transforms the distance vector (dx,dy) by matrix. This is similar to cairo_matrix_transform_point() except that the translation components of the transformation are ignored. The calculation of the returned vector is as follows:

cairo_matrix_transform_distance(matrix, dx, dy)

Arguments

matrix	[cairo_matrix_t *] a #cairo_matrix_t
dx	[double *] X component of a distance vector. An in/out parameter
dy	[double *] Y component of a distance vector. An in/out parameter

Details

<programlisting> dx2 = dx1 * a + dy1 * c; dy2 = dx1 * b + dy1 * d; </programlisting>

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.

Since: 1.0

C function prototype: void cairo_matrix_transform_distance (const cairo_matrix_t *matrix, double *dx, double *dy)

See also

Other cairo-matrix: cairo_matrix_init_rotate(), cairo_matrix_init_scale(), cairo_matrix_init_translate(), cairo_matrix_init(), cairo_matrix_invert(), cairo_matrix_multiply(), cairo_matrix_rotate(), cairo_matrix_scale(), cairo_matrix_transform_point(), cairo_matrix_translate()