d2pl2: added RGBA and SetRGBA methods (to implement HellSpawner/hswidget/hspalettegridwidget.PaletteColor)

d2common/d2fileformats/d2pl2/pl2_color.go

@@ -1,5 +1,12 @@
 package d2pl2
 
+const (
+	bitShift0 = 8 * iota
+	bitShift8
+	bitShift16
+	bitShift24
+)
+
 // PL2Color represents an RGBA color
 type PL2Color struct {
 	R uint8
@@ -7,3 +14,33 @@ type PL2Color struct {
 	B uint8
 	_ uint8
 }
+
+const (
+	mask = 0xff
+)
+
+func (p *PL2Color) RGBA() uint32 {
+	return toComposite(p.R, p.G, p.B, mask)
+}
+
+func (p *PL2Color) SetRGBA(rgba uint32) {
+	p.R, p.G, p.B, _ = toComponent(rgba)
+}
+
+func toComposite(w, x, y, z uint8) uint32 {
+	composite := uint32(w) << bitShift24
+	composite += uint32(x) << bitShift16
+	composite += uint32(y) << bitShift8
+	composite += uint32(z) << bitShift0
+
+	return composite
+}
+
+func toComponent(wxyz uint32) (w, x, y, z uint8) {
+	w = uint8(wxyz >> bitShift24 & mask)
+	x = uint8(wxyz >> bitShift16 & mask)
+	y = uint8(wxyz >> bitShift8 & mask)
+	z = uint8(wxyz >> bitShift0 & mask)
+
+	return w, x, y, z
+}