cairo/pattern.go
func (v *Pattern) AddColorStopRGBA(offset, red, green, blue, alpha float64) error {
	C.cairo_pattern_add_color_stop_rgba(v.native(), C.double(offset),
		C.double(red), C.double(green), C.double(blue), C.double(alpha))
	return v.Status().ToError()
}
func (v *Pattern) AddColorStopRGBA(offset, red, green, blue, alpha float64) error {
	C.cairo_pattern_add_color_stop_rgba(v.native(), C.double(offset),
		C.double(red), C.double(green), C.double(blue), C.double(alpha))
	return v.Status().ToError()
}
// AddColorStopRGBA is a wrapper around cairo_pattern_add_color_stop_rgba().