package ui

import (
	"opslag.de/schobers/galleg/allegro5"
)

var dropShadowPalette []allegro5.Color

func initDropShadowPalette() {
	if nil != dropShadowPalette {
		return
	}
	dropShadowPalette = []allegro5.Color{
		allegro5.NewColorAlpha(0, 0, 0, 0x0f),
		allegro5.NewColorAlpha(0, 0, 0, 0x07),
		allegro5.NewColorAlpha(0, 0, 0, 0x03),
	}
}

func DropShadow(x1, y1, x2, y2 float32) {
	initDropShadowPalette()

	allegro5.DrawLine(x1, y2+1, x2+1, y2+1, dropShadowPalette[0], 1)
	allegro5.DrawLine(x2+1, y1, x2+1, y2, dropShadowPalette[0], 1)
	allegro5.DrawLine(x1, y2+2, x2+2, y2+2, dropShadowPalette[1], 1)
	allegro5.DrawLine(x2+2, y1, x2+2, y2+1, dropShadowPalette[1], 1)
	allegro5.DrawLine(x1+1, y2+3, x2+2, y2+3, dropShadowPalette[2], 1)
	allegro5.DrawLine(x2+3, y1+1, x2+3, y2+2, dropShadowPalette[2], 1)
}