57_Wolve
03a47deade
Create Release & Upload Assets / Upload Assets To Gitea w/ goreleaser (push) Failing after 11s
144 lines
3.0 KiB
Go
144 lines
3.0 KiB
Go
// stolen and modified from https://github.com/mugli/png2escpos
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package escpos
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import (
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"fmt"
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"image"
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)
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func closestNDivisibleBy8(n int) int {
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q := n / 8
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n1 := q * 8
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return n1
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}
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func printImage(img image.Image) (xL byte, xH byte, yL byte, yH byte, data []byte) {
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width, height, pixels := getPixels(img)
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removeTransparency(&pixels)
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makeGrayscale(&pixels)
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printWidth := closestNDivisibleBy8(width)
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printHeight := closestNDivisibleBy8(height)
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bytes, _ := rasterize(printWidth, printHeight, &pixels)
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return byte((printWidth >> 3) & 0xff), byte(((printWidth >> 3) >> 8) & 0xff), byte(printHeight & 0xff), byte((printHeight >> 8) & 0xff), bytes
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}
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func makeGrayscale(pixels *[][]pixel) {
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height := len(*pixels)
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width := len((*pixels)[0])
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for y := 0; y < height; y++ {
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row := (*pixels)[y]
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for x := 0; x < width; x++ {
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pixel := row[x]
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luminance := (float64(pixel.R) * 0.299) + (float64(pixel.G) * 0.587) + (float64(pixel.B) * 0.114)
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var value int
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if luminance < 128 {
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value = 0
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} else {
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value = 255
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}
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pixel.R = value
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pixel.G = value
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pixel.B = value
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row[x] = pixel
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}
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}
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}
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func removeTransparency(pixels *[][]pixel) {
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height := len(*pixels)
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width := len((*pixels)[0])
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for y := 0; y < height; y++ {
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row := (*pixels)[y]
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for x := 0; x < width; x++ {
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pixel := row[x]
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alpha := pixel.A
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invAlpha := 255 - alpha
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pixel.R = (alpha*pixel.R + invAlpha*255) / 255
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pixel.G = (alpha*pixel.G + invAlpha*255) / 255
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pixel.B = (alpha*pixel.B + invAlpha*255) / 255
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pixel.A = 255
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row[x] = pixel
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}
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}
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}
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func rasterize(printWidth int, printHeight int, pixels *[][]pixel) ([]byte, error) {
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if printWidth%8 != 0 {
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return nil, fmt.Errorf("printWidth must be a multiple of 8")
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}
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if printHeight%8 != 0 {
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return nil, fmt.Errorf("printHeight must be a multiple of 8")
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}
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bytes := make([]byte, (printWidth*printHeight)>>3)
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for y := 0; y < printHeight; y++ {
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for x := 0; x < printWidth; x = x + 8 {
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i := y*(printWidth>>3) + (x >> 3)
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bytes[i] =
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byte((getPixelValue(x+0, y, pixels) << 7) |
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(getPixelValue(x+1, y, pixels) << 6) |
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(getPixelValue(x+2, y, pixels) << 5) |
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(getPixelValue(x+3, y, pixels) << 4) |
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(getPixelValue(x+4, y, pixels) << 3) |
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(getPixelValue(x+5, y, pixels) << 2) |
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(getPixelValue(x+6, y, pixels) << 1) |
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getPixelValue(x+7, y, pixels))
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}
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}
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return bytes, nil
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}
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func getPixelValue(x int, y int, pixels *[][]pixel) int {
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row := (*pixels)[y]
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pixel := row[x]
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if pixel.R > 0 {
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return 0
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}
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return 1
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}
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func rgbaToPixel(r uint32, g uint32, b uint32, a uint32) pixel {
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return pixel{int(r >> 8), int(g >> 8), int(b >> 8), int(a >> 8)}
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}
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type pixel struct {
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R int
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G int
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B int
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A int
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}
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func getPixels(img image.Image) (int, int, [][]pixel) {
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bounds := img.Bounds()
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width, height := bounds.Max.X, bounds.Max.Y
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var pixels [][]pixel
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for y := 0; y < height; y++ {
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var row []pixel
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for x := 0; x < width; x++ {
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row = append(row, rgbaToPixel(img.At(x, y).RGBA()))
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}
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pixels = append(pixels, row)
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}
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return width, height, pixels
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}
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