109 lines
2.1 KiB
Go
109 lines
2.1 KiB
Go
//+build cgo
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package thumbnail
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import (
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"bytes"
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"fmt"
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"image"
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"image/color"
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"image/png"
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"code.ivysaur.me/imagequant/v2"
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)
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func goImageToRgba32(im image.Image) []byte {
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w := im.Bounds().Max.X
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h := im.Bounds().Max.Y
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ret := make([]byte, w*h*4)
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p := 0
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for y := 0; y < h; y += 1 {
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for x := 0; x < w; x += 1 {
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r16, g16, b16, a16 := im.At(x, y).RGBA() // Each value ranges within [0, 0xffff]
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ret[p+0] = uint8(r16 >> 8)
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ret[p+1] = uint8(g16 >> 8)
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ret[p+2] = uint8(b16 >> 8)
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ret[p+3] = uint8(a16 >> 8)
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p += 4
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}
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}
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return ret
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}
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func rgb8PaletteToGoImage(w, h int, rgb8data []byte, pal color.Palette) image.Image {
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rect := image.Rectangle{
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Max: image.Point{
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X: w,
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Y: h,
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},
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}
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ret := image.NewPaletted(rect, pal)
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for y := 0; y < h; y += 1 {
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for x := 0; x < w; x += 1 {
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ret.SetColorIndex(x, y, rgb8data[y*h+x])
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}
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}
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return ret
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}
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func crushFast(img image.Image) ([]byte, error) {
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return crush(img, imagequant.SPEED_FASTEST)
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}
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func crush(img image.Image, speed int) ([]byte, error) {
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width := img.Bounds().Max.X
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height := img.Bounds().Max.Y
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attr, err := imagequant.NewAttributes()
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if err != nil {
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return nil, fmt.Errorf("NewAttributes: %s", err.Error())
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}
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defer attr.Release()
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err = attr.SetSpeed(speed)
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if err != nil {
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return nil, fmt.Errorf("SetSpeed: %s", err.Error())
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}
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rgba32data := goImageToRgba32(img)
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iqm, err := imagequant.NewImage(attr, string(rgba32data), width, height, 0)
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if err != nil {
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return nil, fmt.Errorf("NewImage: %s", err.Error())
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}
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defer iqm.Release()
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res, err := iqm.Quantize(attr)
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if err != nil {
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return nil, fmt.Errorf("Quantize: %s", err.Error())
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}
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defer res.Release()
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rgb8data, err := res.WriteRemappedImage()
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if err != nil {
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return nil, fmt.Errorf("WriteRemappedImage: %s", err.Error())
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}
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im2 := rgb8PaletteToGoImage(res.GetImageWidth(), res.GetImageHeight(), rgb8data, res.GetPalette())
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buff := bytes.Buffer{}
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penc := png.Encoder{
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CompressionLevel: png.BestCompression,
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}
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err = penc.Encode(&buff, im2)
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if err != nil {
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return nil, fmt.Errorf("png.Encode: %s", err.Error())
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}
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return buff.Bytes(), nil
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}
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