57 lines
1.2 KiB
Go
57 lines
1.2 KiB
Go
package common
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import (
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"image"
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"image/color"
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)
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type BlendMode int
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const (
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Add BlendMode = iota
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)
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func Blend(src, dest *image.RGBA, mode BlendMode) *image.RGBA {
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img := image.NewRGBA(src.Bounds())
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for i := 0; i < src.Bounds().Max.X; i++ {
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for j := 0; j < src.Bounds().Max.Y; j++ {
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switch mode {
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case Add:
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if compareColor(src.RGBAAt(i, j), Black) {
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img.Set(i, j, dest.RGBAAt(i, j))
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} else {
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img.SetRGBA(i, j, add(src.RGBAAt(i, j), dest.RGBAAt(i, j)))
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}
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}
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}
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}
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return img
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}
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func compareColor(src, dst color.RGBA) bool {
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sr, sg, sb, sa := src.R, src.G, src.B, src.A
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dr, dg, db, da := dst.R, dst.G, dst.B, dst.A
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if sr == dr && sg == dg && sb == db && sa == da {
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return true
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}
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return false
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}
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func add(srcC, dstC color.RGBA) color.RGBA {
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c := color.RGBA{}
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sr, sg, sb, sa := srcC.R, srcC.G, srcC.B, srcC.A
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dr, dg, db, da := dstC.R, dstC.G, dstC.B, dstC.A
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aSrc := float64(sa) / 255.0
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aDst := 1.0 - aSrc
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c.R = uint8(ConstrainInt(int(float64(sr)*aSrc+float64(dr)*aDst), 0, 255))
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c.G = uint8(ConstrainInt(int(float64(sg)*aSrc+float64(dg)*aDst), 0, 255))
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c.B = uint8(ConstrainInt(int(float64(sb)*aSrc+float64(db)*aDst), 0, 255))
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c.A = uint8(ConstrainInt(int(float64(sa)*aSrc+float64(da)*aDst), 0, 255))
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return c
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}
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