Function gdk_pixbuf_sys::gdk_pixbuf_add_alpha

pub unsafe extern "C" fn gdk_pixbuf_add_alpha(
    pixbuf: *const GdkPixbuf, 
    substitute_color: gboolean, 
    r: c_uchar, 
    g: c_uchar, 
    b: c_uchar
) -> *mut GdkPixbuf