36 lines
1.1 KiB
Go
36 lines
1.1 KiB
Go
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package imgedit
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import (
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"image"
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"image/color"
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"github.com/disintegration/imaging"
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)
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func makeBoxShadow(maskImg image.Image, shadowColor color.Color, sigma float64, shadowMargin, offsetY int) image.Image {
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w, h := maskImg.Bounds().Dx(), maskImg.Bounds().Dy()
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cr, cg, cb, _ := shadowColor.RGBA()
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cr8, cg8, cb8 := uint8(cr>>8), uint8(cg>>8), uint8(cb>>8)
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// New box image
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backing := image.NewNRGBA(image.Rect(0, 0, w+shadowMargin*2, h+shadowMargin*2+offsetY))
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newImg := image.NewNRGBA(image.Rect(0, 0, w+shadowMargin*2, h+shadowMargin*2+offsetY))
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for x := 0; x < w+shadowMargin*2; x++ {
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for y := 0; y < h+shadowMargin*2; y++ {
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var c = color.NRGBA{R: 255, G: 255, B: 255, A: 0}
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if x >= shadowMargin-4 && y >= shadowMargin-4 && x <= w+shadowMargin+4 && y <= h+shadowMargin+4 {
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_, _, _, a := maskImg.At(x-shadowMargin, y-shadowMargin).RGBA()
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c = color.NRGBA{R: cr8, G: cg8, B: cb8, A: uint8(a >> 8)}
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}
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backing.SetNRGBA(x, y, color.NRGBA{R: 255, G: 255, B: 255, A: 0})
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newImg.SetNRGBA(x, y+offsetY, c)
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}
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}
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// Blur
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blurredImage := imaging.Blur(newImg, sigma)
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backing = imaging.OverlayCenter(backing, blurredImage, 0.6)
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return backing
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}
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