Initial commit

.gitignore

@@ -0,0 +1,2 @@
+image-transcoder.exe
+main.log

codec/coder.go

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+package codec
+
+import (
+	"bytes"
+	"image"
+	"io"
+)
+
+type Coder interface {
+	Decode(io.Reader) (image.Image, error)
+	Encode(image.Image, int) (bytes.Buffer, error)
+}

codec/jpeg.go

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+package codec
+
+import (
+	"bytes"
+	"image"
+	"image/jpeg"
+	"io"
+)
+
+type JPGCoder struct{}
+
+func (coder JPGCoder) Decode(r io.Reader) (image.Image, error) {
+	i, err := jpeg.Decode(r)
+	if err != nil {
+		return nil, err
+	}
+	return i, nil
+}
+
+func (coder JPGCoder) Encode(i image.Image, quality int) (buf bytes.Buffer, err error) {
+	err = jpeg.Encode(&buf, i, &jpeg.Options{Quality: quality})
+	return buf, err
+}

codec/png.go

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+package codec
+
+import (
+	"bytes"
+	"github.com/foobaz/lossypng/lossypng"
+	"image"
+	"image/png"
+	"io"
+)
+
+type PNGCoder struct{}
+
+const qMax = 20
+
+func (coder PNGCoder) Decode(r io.Reader) (image.Image, error) {
+	i, err := png.Decode(r)
+	if err != nil {
+		return nil, err
+	}
+	return i, nil
+}
+
+func (coder PNGCoder) Encode(i image.Image, quality int) (buf bytes.Buffer, err error) {
+	c := lossypng.Compress(i, 2, qualityFactor(quality))
+	err = png.Encode(&buf, c)
+	return buf, err
+}
+
+// qualityFactor normalizes the PNG quality factor from a max of 20, where 0 is
+// no conversion.
+func qualityFactor(q int) int {
+	f := q / 100
+	return qMax - (f * qMax)
+}

codec/webp.go

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+package codec
+
+import (
+	"bytes"
+	"image"
+	"io"
+
+	"github.com/chai2010/webp"
+)
+
+type WebpCoder struct{}
+
+func (coder WebpCoder) Decode(r io.Reader) (image.Image, error) {
+	i, err := webp.Decode(r)
+	if err != nil {
+		return nil, err
+	}
+	return i, nil
+}
+
+func (coder WebpCoder) Encode(i image.Image, quality int) (buf bytes.Buffer, err error) {
+	if err = webp.Encode(&buf, i, &webp.Options{Lossless: true, Quality: float32(quality)}); err != nil {
+		return buf, err
+	}
+	return buf, nil
+}

go.mod

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+module image-transcoder
+
+go 1.23.0
+
+require (
+	github.com/chai2010/webp v1.1.1
+	github.com/foobaz/lossypng v0.0.0-20200814224715-48fa8819852a
+)

go.sum

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+github.com/chai2010/webp v1.1.1 h1:jTRmEccAJ4MGrhFOrPMpNGIJ/eybIgwKpcACsrTEapk=
+github.com/chai2010/webp v1.1.1/go.mod h1:0XVwvZWdjjdxpUEIf7b9g9VkHFnInUSYujwqTLEuldU=
+github.com/foobaz/lossypng v0.0.0-20200814224715-48fa8819852a h1:0TYY/syyvt/+y5PWAkybgG2o6zHY+UrI3fuixaSeRoI=
+github.com/foobaz/lossypng v0.0.0-20200814224715-48fa8819852a/go.mod h1:wRxTcIExb9GZAgOr1wrQuOZBkyoZNQi7znUmeyKTciA=

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"image-transcoder/codec"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+)
+
+var codecs = map[string]codec.Coder{
+	".jpg":  codec.JPGCoder{},
+	".jpeg":  codec.JPGCoder{},
+	".png":  codec.PNGCoder{},
+	".webp": codec.WebpCoder{},
+}
+
+var Error *log.Logger
+var Warning *log.Logger
+
+func init() {
+	log.SetFlags(log.Lmicroseconds | log.Lshortfile)
+	logger := io.MultiWriter(os.Stdout)
+	log.SetOutput(logger)
+
+	Error = log.New(io.MultiWriter(os.Stderr, os.Stdout),
+		fmt.Sprintf("%sERROR:%s ", "\033[0;101m", "\033[0m"),
+		log.Lmicroseconds|log.Lshortfile)
+	Warning = log.New(io.MultiWriter(os.Stdout),
+		fmt.Sprintf("%sWarning:%s ", "\033[0;93m", "\033[0m"),
+		log.Lmicroseconds|log.Lshortfile)
+}
+
+func main() {
+	quality := flag.Int("quality", 80, "Quality of the image")
+	to := flag.String("to", ".jpg", "Extension to transcode to")
+	nosafe := flag.Bool("nosafe", false, "Prevents backup of the original before encoding")
+	flag.Parse()
+
+	if _, ok := codecs[*to]; !ok {
+		Error.Println("Invalid extension")
+		return
+	}
+
+	log.Printf("Using quality: %d", *quality)
+	log.Printf("Transcoding to: %s", *to)
+	log.Printf("Nosafe mode: %v", *nosafe)
+
+	var wg sync.WaitGroup
+	for _, file := range flag.Args() {
+		wg.Add(1)
+		go func(file string) {
+			defer wg.Done()
+			file = filepath.ToSlash(file)
+			file = filepath.Clean(file)
+			ext := filepath.Ext(file)
+			coder, ok := codecs[ext]
+			if !ok {
+				Error.Printf("No encoder found for file: %s", file)
+				return
+			}
+			log.Printf("%#v", coder)
+
+			filename := filepath.Base(file)
+			if *nosafe {
+				bckp := filename + ".bak"
+				err := os.Link(file, bckp)
+				if err != nil {
+					Error.Printf("Failed to backup file: %v", err)
+					return
+				}
+			}
+
+			filehandle, err := os.Open(file)
+			if err != nil {
+				Error.Printf("Failed to open file: %v", err)
+				return
+			}
+
+			log.Printf("Decoding %s", file)
+			image, err := coder.Decode(filehandle)
+			if err != nil {
+				Error.Printf("Failed to decode file: %v", err)
+				return
+			}
+			filehandle.Close()
+
+			newfile := strings.Replace(filename, ext, *to, 1)
+			log.Printf("Encoding %s to %s", file, newfile)
+
+			buf, err := coder.Encode(image, *quality)
+			if err != nil {
+				Error.Printf("Failed to encode image: %v", err)
+				return
+			}
+
+			filehandle, err = os.Create(newfile)
+			if err != nil {
+				Error.Printf("Failed to create file %s: %v", newfile, err)
+				return
+			}
+
+			n, err := filehandle.Write(buf.Bytes())
+			if n != len(buf.Bytes()) || err != nil {
+				Error.Printf("Failed to write file %s: %v", newfile, err)
+				return
+			}
+			log.Printf("Wrote %d bytes to %s", n, newfile)
+		}(file)
+	}
+	wg.Wait()
+}

sync

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+image-transcoder.exe,"C:\Program Files\Git\usr\bin\itrans.exe"