Module xblend::blend

Some blend modes

Assume that we have to colors called src and dst
The output is the result color

Traits

Clear	Clear blending mode output = (0,0,0,0)
Darken	Darken blending mode output = src.gray < dst.gray ? src : dst
Dst	Dst blending mode output = dst
DstATop	DstATop blending mode output = src * (1 - dst.alpha) + dst * src.alpha
DstIn	DstIn blending mode output = dst * src.alpha
DstOut	SrcOut blending mode output = src * (1 - dst.alpha)
DstOver	DstOver blending mode output = src * (1 - dst.alpha) + dst
Lighten	Darken blending mode output = src.gray > dst.gray ? src : dst
Multiply	Multiply blending mode output = src * dst
Screen	Screen blending mode output = 1 - (1 - src) * (1 - dst)
Src	Src blending mode output = src
SrcATop	SrcATop blending mode output = src * dst.alpha + dst * (1 - src.alpha)
SrcIn	SrcIn blending mode output = src * dst.alpha
SrcOut	SrcOut blending mode output = dst * (1 - src.alpha)
SrcOver	SrcOver blending mode output = src + dst * (1 - src.alpha)
Xor	Xor blending mode output = src * (1 - dst.alpha) + dst * (1 - src.alpha)