golang version image convert to ascii/txt--go版本的图片转字符画

image2txt.go

package main

import (
	"image"
	"image/color"
	"os"
	"fmt"
	"net/http"
	"log"
	"image/jpeg"
	"strconv"
	"strings"
	"image/png"
	"image/gif"
	"github.com/kataras/iris/core/errors"
)

//这些值可以去网上搜索，也可以自己算出（还不会）
const str = "@80GCLft1i;:,."

//const str = "##@@MMBB88NNHHOOGGPPEEXXFFVVYY22ZZCC77LLjjll11rrii;;;:::....  "

//编辑器的字符的宽高比， 编辑器的行距太高，不处理可能会变形。这里是vsCode windows版的比例
const wordRatio = float32(36) / float32(15)

//const wordRatio =  1

const (
	sizeSmall  = 80
	sizeMedium = 160
	sizeLarge  = 320
)

//主要是 image 包的基本使用
func main() {

	arg := os.Args

	if arg == nil || len(arg) != 3 {
		usage()
		return
	}

	size, err := strconv.Atoi(arg[1])
	if err != nil {
		usage()
		return
	}
	url := arg[2]

	// test data
	//size := sizeSmall
	//url := "https://www.v2ex.com/static/img/v2ex@2x.png"
	img := download(url)
	rgb := color2Gray(img)
	rgbSmall := small(rgb, size, wordRatio)
	image2ascii(*rgbSmall)

}

func usage() {
	fmt.Println(`格式
  size url
`)
}

//下载图片
func download(url string) image.Image {
	var err error
	resp, err := http.Get(url)

	if err != nil {
		log.Fatalln(err)
	}
	defer resp.Body.Close()
	var img image.Image
	if strings.HasSuffix(url, ".png") {
		img, err = png.Decode(resp.Body)
	} else if strings.HasSuffix(url, ".jpg") {
		img, err = jpeg.Decode(resp.Body)
	} else if strings.HasSuffix(url, ".gif") {
		img, err = gif.Decode(resp.Body)
	} else {
		err = errors.New("not an image")
	}
	if err != nil {
		log.Fatalln(err)
	}
	return img
}

//压缩图片
func small(img *image.RGBA, size int, wordRatio float32) *image.RGBA {

	dx := img.Bounds().Dx()
	dy := img.Bounds().Dy()

	scale := float32(dx) / float32(size)
	wh := float32(dx) / float32(dy)
	rgbSmall := image.NewRGBA(image.Rect(0, 0, size, int(float32(size)/(wh*wordRatio))))

	bounds := rgbSmall.Bounds()
	for i := 0; i < bounds.Dx(); i ++ {
		for j := 0; j < bounds.Dy(); j++ {
			var gray2 int

			c2 := img.RGBAAt(int(float32(i)*scale), int(float32(j)*scale*wordRatio))
			c3 := img.RGBAAt(int(float32(i)*scale)+1, int(float32(j)*scale*wordRatio))
			c4 := img.RGBAAt(int(float32(i)*scale)-1, int(float32(j)*scale*wordRatio))
			c5 := img.RGBAAt(int(float32(i)*scale), int(float32(j)*scale*wordRatio-1))
			c6 := img.RGBAAt(int(float32(i)*scale), int(float32(j)*scale*wordRatio+1))
			gray2 = (int(c2.R) + int(c3.R) + int(c4.R) + int(c5.R) + int(c6.R)) / 5

			c := color.RGBA{R: uint8(gray2), G: uint8(gray2), B: uint8(gray2)}
			rgbSmall.SetRGBA(i, j, c)
		}
	}

	return rgbSmall

}

//灰度化图片
func color2Gray(img image.Image) (*image.RGBA) {
	bounds := img.Bounds()

	w := bounds.Dx()
	h := bounds.Dy()

	newRgba := image.NewRGBA(bounds)

	for i := 0; i < w; i ++ {
		for j := 0; j < h; j++ {
			cl := img.At(i, j)
			r, g, b, _ := cl.RGBA()
			gray := (r*30 + g*59 + b*11 + 50) / 100
			newC := color.RGBA{R: uint8(gray), G: uint8(gray), B: uint8(gray)}
			newRgba.SetRGBA(i, j, newC)
		}
	}

	return newRgba
}

//灰度化的图片转文字
func image2ascii(img image.RGBA) {

	file, err := os.Create("out.txt")
	defer file.Close()
	if err != nil {
		fmt.Println(err)
	}

	s, _ := gray2ascii(img)

	file.WriteString(s)

}

func gray2ascii(img image.RGBA) (output string, original string) {
	bounds := img.Bounds()

	w := bounds.Dx()
	h := bounds.Dy()

	for i := 0; i < h; i ++ {
		line := ""
		line2 := ""
		for j := 0; j < w; j++ {
			gray := img.RGBAAt(j, i).R
			num := int(gray) * len(str) / 256

			line += string(str[num])
			line2 += strconv.Itoa(int(gray)) + ","
		}
		line += "\n"
		line2 += "\n"
		output += line
		original += line2
	}

	return
}