123 lines
2.6 KiB
Go
123 lines
2.6 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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"image/png"
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"golang.org/x/image/bmp"
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"golang.org/x/image/draw"
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)
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func (this *DirectThumbnailer) scaleImage(src image.Image) (image.Image, error) {
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srcW := src.Bounds().Max.X
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srcH := src.Bounds().Max.Y
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var srcCopyPosition, destCopyPosition image.Rectangle
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switch this.cfg.Aspect {
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case FitInside:
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var destW, destH int
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if srcW > srcH {
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destW = this.cfg.Width
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destH = this.cfg.Height * srcH / srcW
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} else {
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destW = this.cfg.Width * srcW / srcH
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destH = this.cfg.Height
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}
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offsetX := (this.cfg.Width - destW) / 2
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offsetY := (this.cfg.Height - destH) / 2
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srcCopyPosition = src.Bounds()
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destCopyPosition = image.Rect(offsetX, offsetY, destW+offsetX, destH+offsetY)
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case FitOutside:
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var srcSmallestDim, offsetX, offsetY int
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if srcW > srcH {
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// Landscape
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srcSmallestDim = srcH
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offsetY = 0
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offsetX = (srcW - srcH) / 2
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} else {
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// Portrait (or square)
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srcSmallestDim = srcW
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offsetY = (srcH - srcW) / 2
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offsetX = 0
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}
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srcCopyPosition = image.Rect(offsetX, offsetY, srcSmallestDim+offsetX, srcSmallestDim+offsetY)
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destCopyPosition = image.Rect(0, 0, this.cfg.Width, this.cfg.Height)
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case Stretch:
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srcCopyPosition = src.Bounds()
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destCopyPosition = image.Rect(0, 0, this.cfg.Width, this.cfg.Height)
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default:
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return nil, ErrInvalidOption
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}
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//
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dest := image.NewRGBA(image.Rect(0, 0, this.cfg.Width, this.cfg.Height))
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// For a transparent destination, Op.Src is faster than Op.Over
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switch this.cfg.Scale {
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case NearestNeighbour:
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draw.NearestNeighbor.Scale(dest, destCopyPosition, src, srcCopyPosition, draw.Src, nil)
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case BilinearFast:
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draw.ApproxBiLinear.Scale(dest, destCopyPosition, src, srcCopyPosition, draw.Src, nil)
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case BilinearAccurate:
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draw.BiLinear.Scale(dest, destCopyPosition, src, srcCopyPosition, draw.Src, nil)
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case Bicubic:
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draw.CatmullRom.Scale(dest, destCopyPosition, src, srcCopyPosition, draw.Src, nil)
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}
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return dest, nil
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}
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func (this *DirectThumbnailer) encode(dest image.Image) ([]byte, error) {
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switch this.cfg.Output {
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case Png:
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buff := bytes.Buffer{}
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err := png.Encode(&buff, dest)
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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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case PngCrush:
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return crushFast(dest)
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case Jpeg:
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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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case Bmp:
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buff := bytes.Buffer{}
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err := bmp.Encode(&buff, dest)
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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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