Warning
gdk_gc_set_function has been deprecated since version 2.22 and should not be used in newly-written code. Use cairo_set_operator() with Cairo.
Determines how the current pixel values and the
pixel values being drawn are combined to produce
the final pixel values.
Warning gdk_gc_set_function has been deprecated since version 2.22 and should not be used in newly-written code. Use cairo_set_operator() with Cairo. Determines how the current pixel values and the pixel values being drawn are combined to produce the final pixel values.