78 lines
1.6 KiB
Go
78 lines
1.6 KiB
Go
package thumbnail
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import (
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"bytes"
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"image"
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"image/jpeg"
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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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switch this.sfmt {
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case SCALEFMT_BILINEAR:
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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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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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case SCALEFMT_NN:
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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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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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}
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}
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switch this.ofmt {
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case OUTPUT_PNG_CRUSH:
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return crushFast(dest)
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case OUTPUT_JPG:
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buff := bytes.Buffer{}
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err := jpeg.Encode(&buff, dest, &jpeg.Options{Quality: jpeg.DefaultQuality})
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if err != nil {
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return nil, err
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}
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return buff.Bytes(), nil
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default:
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return nil, ErrInvalidOption
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}
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}
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