<div dir="ltr">When skewing in the x direction, top x seems to move to the right a bit.I have attached a png. The red rectangle is not skewed, while the black is skewed at 45. The skewed (black) rectangle looks shifted to the right a few pixels. That is the top is not aligned. I would think there should be a diagonal line cutting through the top left hitting the bottom right corner. From my past history, I am probably doing something wrong. Thanks in advance. #include <cairo.h> #include <math.h> #include <string.h> #include <stdlib.h> /* <a href="http://cairographics.org/cookbook/matrix_transform/http://cairographics.org/cookbook/matrix_transform/">http://cairographics.org/cookbook/matrix_transform/http://cairographics.org/cookbook/matrix_transform/</a> Lets take that C = math.cos(A), S = math.sin(A), T = math.tan(A) X-skew by A -- mtrx = cairo.Matrix(1,0,T,1,0,0) Y-skew by A -- mtrx = cairo.Matrix(1,T,0,1,0,0) */ int main (int argc, char *argv[]) { cairo_surface_t* cs; cairo_t *cr; double angle; double skewx; cairo_matrix_t matrix; cs= cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 130.,100.); cr= cairo_create(cs); cairo_set_source_rgb(cr, 1., 0., 0.); cairo_rectangle(cr, 10., 10., 50., 50.); cairo_stroke(cr); angle= 45.; skewx= tan(angle * M_PI / 180.); cairo_matrix_init( &matrix, 1.0, 0.0, skewx, 1.0, 0.0, 0.0); cairo_transform(cr, &matrix); cairo_rectangle(cr, 10., 10., 50., 50.); cairo_set_source_rgb(cr, 0., 0., 0.); cairo_stroke(cr); cairo_surface_write_to_png(cs, "skew.png"); cairo_destroy(cr); cairo_surface_destroy(cs); return 0; } </div>