105 lines
2.3 KiB
Go
105 lines
2.3 KiB
Go
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package catprinter
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import (
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"github.com/disintegration/imaging"
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"github.com/makeworld-the-better-one/dither/v2"
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"image"
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"image/color"
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"image/draw"
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"log"
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)
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const printWidth = 384
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func convertImageToBytes(img image.Image) ([]byte, error) {
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if img.Bounds().Dx() != printWidth {
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return nil, ErrInvalidImageSize
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}
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var byteArray []byte
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for y := 0; y < img.Bounds().Dy(); y++ {
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for x := 0; x < img.Bounds().Dx(); x++ {
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r, g, b, _ := img.At(x, y).RGBA()
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if r != g || g != b || r != b || (r != 0 && r != 65535) {
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return nil, ErrNotBlackWhite
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}
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if r == 0 {
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byteArray = append(byteArray, 1) // black
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} else {
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byteArray = append(byteArray, 0) // white
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}
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}
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}
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return byteArray, nil
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}
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func grayscaleToBlackWhite(img image.Image, blackPoint float32) *image.NRGBA {
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bounds := img.Bounds()
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nrgbaImg := image.NewNRGBA(bounds)
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draw.Draw(nrgbaImg, bounds, img, bounds.Min, draw.Src)
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for y := 0; y < img.Bounds().Dy(); y++ {
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for x := 0; x < img.Bounds().Dx(); x++ {
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r, g, b, _ := img.At(x, y).RGBA()
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if r != g || g != b || r != b {
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log.Panicln("logic error, image should have been grayscale")
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}
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if float32(r)/65535 < blackPoint {
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nrgbaImg.Set(x, y, color.Black)
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} else {
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nrgbaImg.Set(x, y, color.White)
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}
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}
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}
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return nrgbaImg
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}
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func ditherImage(img image.Image, algo dither.ErrorDiffusionMatrix) image.Image {
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palette := []color.Color{
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color.Black,
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color.White,
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}
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d := dither.NewDitherer(palette)
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d.Matrix = algo
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return d.Dither(img)
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}
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// FormatImage formats the image for printing by resizing it and dithering or grayscaling it
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func (c *Client) FormatImage(img image.Image, opts *PrinterOptions) image.Image {
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if img.Bounds().Dx() > img.Bounds().Dy() && opts.autoRotate {
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img = imaging.Rotate90(img)
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}
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var newImg image.Image = imaging.New(img.Bounds().Dx(), img.Bounds().Dy(), color.White)
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newImg = imaging.OverlayCenter(newImg, img, 1)
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newImg = imaging.Resize(newImg, printWidth, 0, imaging.NearestNeighbor)
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if opts.dither {
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newImg = ditherImage(newImg, opts.ditherAlgo)
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} else {
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newImg = imaging.Grayscale(newImg)
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newImg = grayscaleToBlackWhite(newImg, opts.blackPoint)
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}
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if c.Debug.DumpImage {
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err := imaging.Save(newImg, "./image.png")
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if err != nil {
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log.Println("failed to save debugging image dump", err.Error())
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}
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}
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return newImg
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}
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