99 lines
2.1 KiB
Go
99 lines
2.1 KiB
Go
package thumbnail
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import (
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"image"
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"image/color"
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)
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func Blend(a, b color.Color) color.Color {
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switch a.(type) {
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case color.RGBA:
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return BlendRGBA(a.(color.RGBA), b.(color.RGBA)) // FIXME there's syntax for this
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case color.YCbCr:
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return BlendYCbCr(a.(color.YCbCr), b.(color.YCbCr))
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default:
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return a // ??? unknown color format
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}
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}
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func BlendYCbCr(a, b color.YCbCr) color.YCbCr {
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return color.YCbCr{
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Y: uint8((int(a.Y) + int(b.Y)) / 2),
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Cb: uint8((int(a.Cb) + int(b.Cb)) / 2),
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Cr: uint8((int(a.Cr) + int(b.Cr)) / 2),
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}
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}
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func BlendRGBA(a, b color.RGBA) color.RGBA {
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return color.RGBA{
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R: uint8((int(a.R) + int(b.R)) / 2),
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G: uint8((int(a.G) + int(b.G)) / 2),
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B: uint8((int(a.B) + int(b.B)) / 2),
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A: uint8((int(a.A) + int(b.A)) / 2),
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}
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}
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func (this *Thumbnailer) RenderScaledImage(src image.Image) ([]byte, error) {
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srcW := src.Bounds().Max.X
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srcH := src.Bounds().Max.Y
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destW := 0
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destH := 0
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if srcW > srcH {
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destW = this.Width
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destH = this.Height * srcH / srcW
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} else {
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destW = this.Width * srcW / srcH
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destH = this.Height
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}
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offsetX := (this.Width - destW) / 2
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offsetY := (this.Height - destH) / 2
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scaleW := float64(srcW) / float64(destW)
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scaleH := float64(srcH) / float64(destH)
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dest := image.NewRGBA(image.Rectangle{Max: image.Point{X: this.Width, Y: this.Height}})
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for y := 0; y < destH; y += 1 {
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for x := 0; x < destW; x += 1 {
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/*
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// NN
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mapx := int(float64(x) * scaleW)
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mapy := int(float64(y) * scaleH)
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dest.Set(x+offsetX, y+offsetY, src.At(mapx, mapy))
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*/
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// Bilinear
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c00 := src.At(int(float64(x)*scaleW), int(float64(y)*scaleH))
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c01 := src.At(int((float64(x)+0.5)*scaleW), int(float64(y)*scaleH))
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c10 := src.At(int(float64(x)*scaleW), int((float64(y)+0.5)*scaleH))
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c11 := src.At(int((float64(x)+0.5)*scaleW), int((float64(y)+0.5)*scaleH))
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cBlend := Blend(Blend(c00, c01), Blend(c10, c11))
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dest.Set(x+offsetX, y+offsetY, cBlend)
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}
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}
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/*var b bytes.Buffer*/
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return crush(dest, 3)
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/*
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err := png.Encode(&b, dest)
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if err != nil {
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return nil, err
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}
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*/
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/*
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err := jpeg.Encode(&b, dest, nil)
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if err != nil {
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return nil, err
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}
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return b.Bytes(), nil*/
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}
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