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