jjppeegg.go

package main

import (
	"bytes"
	"flag"
	"fmt"
	"image/jpeg"
	"io"
	"io/ioutil"
	"os"
)

var loop int
var quality int

func init() {
	flag.IntVar(&loop, "i", 3, "loop times")
	flag.IntVar(&quality, "q", 95, "quality")
}

func main() {
	flag.Parse()

	if flag.NArg() != 2 {
		fmt.Println("need input and output")
		return
	}

	f, err := os.Open(flag.Arg(0))
	if err != nil {
		fmt.Println(err)
		return
	}
	defer f.Close()

	opt := &jpeg.Options{
		Quality: quality,
	}

	buf := new(bytes.Buffer)
	io.Copy(buf, f)
	for i := 0; i < loop; i++ {
		img, err := jpeg.Decode(buf)
		if err != nil {
			fmt.Println(err)
			return
		}
		buf.Reset()
		if err := jpeg.Encode(buf, img, opt); err != nil {
			fmt.Println(err)
			return
		}
	}

	if err := ioutil.WriteFile(flag.Arg(1), buf.Bytes(), os.ModePerm); err != nil {
		fmt.Println(err)
		return
	}
}