サムネイル生成くん

thumbnail.go

package main

import (
	"fmt"
	"image"
	"image/jpeg"
	"io/ioutil"
	"os"
	"path"
	"path/filepath"
	"strings"

	"github.com/nfnt/resize"
)

func main() {
	inputDir := os.Args[1]
	outputDir := os.Args[2]

	fmt.Printf("src: %s\n", inputDir)
	fmt.Printf("dst: %s\n", outputDir)

	qualities := []int{60, 80, 90, 100}
	widths := []uint{600, 700, 800, 900, 1000}

	files, err := ioutil.ReadDir(inputDir)
	if err != nil {
		panic(err)
	}
	for _, file := range files {
		if !strings.HasSuffix(file.Name(), ".jpg") {
			continue
		}
		input := path.Join(inputDir, file.Name())
		file, err := os.Open(input)
		if err != nil {
			panic(err)
		}
		img, err := jpeg.Decode(file)
		if err != nil {
			panic(err)
		}
		file.Close()

		id := strings.TrimSuffix(filepath.Base(file.Name()), path.Ext(file.Name()))
		fmt.Printf("  convert %s\n", file.Name())
		for _, quality := range qualities {
			Thumbnail(img, outputDir, id, quality, 1000)
		}
		for _, width := range widths {
			Thumbnail(img, outputDir, id, 80, width)
		}
	}
}

// Thumbnail 生成
func Thumbnail(input image.Image, outputDir string, id string, quality int, width uint) {
	thumbnail := resize.Thumbnail(width, width, input, resize.Lanczos3)
	out, err := os.Create(path.Join(outputDir, fmt.Sprintf("%s_q%dw%d.jpg", id, quality, width)))
	if err != nil {
		panic(err)
	}
	defer out.Close()
	jpeg.Encode(out, thumbnail, &jpeg.Options{Quality: quality})
}