zntg/allg5/color.go

package allg5

// #include <allegro5/allegro.h>
import "C"
import "image/color"

var _ color.Color = &Color{}

type Color struct {
	color C.ALLEGRO_COLOR
}

func NewColor(r, g, b byte) Color {
	return Color{C.al_map_rgb(C.uchar(r), C.uchar(g), C.uchar(b))}
}

func NewColorAlpha(r, g, b, a byte) Color {
	return Color{C.al_map_rgba(C.uchar(r), C.uchar(g), C.uchar(b), C.uchar(a))}
}

func NewColorGo(c color.Color) Color {
	r, g, b, a := c.RGBA()
	return Color{C.al_premul_rgba(C.uchar(r>>8), C.uchar(g>>8), C.uchar(b>>8), C.uchar(a>>8))}
}

// RGBA implements the color.Color interface.
func (c Color) RGBA() (r, g, b, a uint32) {
	var cr, cg, cb, ca C.uchar
	C.al_unmap_rgba(c.color, &cr, &cg, &cb, &ca)
	a = uint32(ca)
	r = uint32(cr) * a
	g = uint32(cg) * a
	b = uint32(cb) * a
	a *= a
	return
}