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91 lines
1.8 KiB
91 lines
1.8 KiB
package main
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import (
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// "fmt"
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"os"
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"image"
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"log"
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"image/png"
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"image/color"
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"github.com/disintegration/gift"
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// "math"
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"flag"
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)
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func LoadImage(filename string) image.Image {
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reader, err := os.Open(filename)
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if err != nil { log.Fatal(err) }
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defer reader.Close()
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img, _, err := image.Decode(reader)
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if err != nil { log.Fatal(err) }
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return img
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}
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func SaveImage(filename string, img image.Image) {
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out, err := os.Create(filename)
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if err != nil {
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log.Fatalf("can't write file %s: %v", filename, err)
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}
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defer out.Close()
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err = png.Encode(out, img)
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if err != nil {
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log.Fatalf("can't png encode %s: %v", filename, err)
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}
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}
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func UpscaleImage(bounds image.Rectangle, smaller *image.NRGBA, pixel_width int) *image.NRGBA {
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upscale := image.NewNRGBA(bounds)
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var from_x, from_y int
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var from color.Color
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for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
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for x := bounds.Min.X; x < bounds.Max.X; x++ {
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if x % pixel_width == 0 {
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from_x = x / pixel_width
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from_y = y / pixel_width
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from = smaller.At(from_x, from_y)
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}
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upscale.Set(x, y, from)
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}
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}
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return upscale
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}
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type Opts struct {
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InFile string
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OutFile string
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PixelWidth int
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}
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func ParseOpts() Opts {
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var opts Opts
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flag.StringVar(&opts.InFile, "input", "", "input file.png")
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flag.StringVar(&opts.OutFile, "output", "", "output file.png")
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flag.IntVar(&opts.PixelWidth, "pixel-width", 4, "pixel width")
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flag.Parse()
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return opts
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}
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func main() {
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opts := ParseOpts()
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src := LoadImage(opts.InFile)
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bounds := src.Bounds()
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resize := gift.Resize(bounds.Max.X / opts.PixelWidth, 0, gift.NearestNeighborResampling)
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g := gift.New(resize)
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smaller := image.NewNRGBA(g.Bounds(bounds))
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g.Draw(smaller, src)
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upscale := UpscaleImage(bounds, smaller, opts.PixelWidth)
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SaveImage(opts.OutFile, upscale)
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}
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