63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
package image
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import (
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"fmt"
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i "image"
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"image/png"
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"io"
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"log"
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"os"
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"golang.org/x/image/draw"
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)
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const (
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thumbnailMaxX = 128
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thumbnailMaxY = 128
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)
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type ThumbType = string
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const ThumbTypeOriginal = "orig"
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const ThumbTypeMarkedUp = "markedup"
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// ThumbPNG writes a thumbnail out to an io.Writer
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func (ip *Store) ThumbPNG(t ThumbType, w io.Writer) error {
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var filename string
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if t == ThumbTypeOriginal {
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filename = ip.OriginalFilename
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} else if t == ThumbTypeMarkedUp {
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filename = ip.ModifiedFilename
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} else {
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log.Fatal("was passed incorrect 'type' arg")
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}
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file, err := os.Open(filename)
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if err != nil {
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return fmt.Errorf("could not open file: %s", err)
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}
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defer file.Close()
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im, _, err := i.Decode(file)
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if err != nil {
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return fmt.Errorf("could not decode file: %s", err)
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}
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newXY := i.Point{}
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if im.Bounds().Max.X/thumbnailMaxX > im.Bounds().Max.Y/thumbnailMaxY {
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newXY.X = thumbnailMaxX
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newXY.Y = im.Bounds().Max.Y / (im.Bounds().Max.X / thumbnailMaxX)
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} else {
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newXY.Y = thumbnailMaxY
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newXY.X = im.Bounds().Max.X / (im.Bounds().Max.Y / thumbnailMaxY)
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}
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dst := i.NewRGBA(i.Rect(0, 0, newXY.X, newXY.Y))
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draw.BiLinear.Scale(dst, dst.Rect, im, im.Bounds(), draw.Over, nil)
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png.Encode(w, dst)
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return nil
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}
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