thumbnails.go

package main

import (
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"sync"

	"github.com/disintegration/imaging"
)

var wg sync.WaitGroup

func main() {
	dir := parse_args()
	// use all CPU cores for maximum performance
	runtime.GOMAXPROCS(runtime.NumCPU())
	filepath.Walk(dir, visit)
	wg.Wait()
}

func visit(p string, info os.FileInfo, err error) error {
	if err != nil {
		panic(err)
	}
	if strings.HasSuffix(p, ".jpg") {
		wg.Add(1)
		go make_thumbnail(p)
	}
	return nil
}

func make_thumbnail(fname string) {
	defer wg.Done()

	img, err := imaging.Open(fname)
	if err != nil {
		panic(err)
	}

	dstImage128 := imaging.Thumbnail(img, 120, 120, imaging.Lanczos)

	err = imaging.Save(dstImage128, fname+"_thumb.jpg")
	if err != nil {
		panic(err)
	}
}

func parse_args() string {
	dir := "."
	if len(os.Args) == 2 {
		dir = os.Args[1]
	}
	return dir
}