package main import ( "fmt" "image/gif" "image/jpeg" "image/png" "io" "io/ioutil" "math" "os" "os/exec" "path/filepath" "github.com/disintegration/imaging" "golang.org/x/image/bmp" "golang.org/x/image/tiff" ) // Goptimize downscales and optimizes an existing image func Goptimize(file string) { info, err := os.Stat(file) if err != nil { fmt.Printf("Error: %s doesn't exist\n", file) return } if !info.Mode().IsRegular() { fmt.Printf("Error: %s is not a file\n", file) return } // open original, rotate if necessary src, err := imaging.Open(file, imaging.AutoOrientation(true)) if err != nil { fmt.Printf("Error: %v (%s)\n", err, file) return } format, err := imaging.FormatFromFilename(file) if err != nil { fmt.Printf("Error: cannot detect format: %v\n", err) return } if format.String() == "GIF" { // return if GIF is animated - unsupported if err := IsGIFAnimated(file); err != nil { fmt.Printf("Error: animated GIF not supported (%v)\n", file) return } } outFilename := filepath.Base(file) outDir := filepath.Dir(file) dstFile := filepath.Join(outDir, outFilename) if outputDir != "" { dstFile = filepath.Join(outputDir, outFilename) } // get original image size srcBounds := src.Bounds() srcW := srcBounds.Dx() srcH := srcBounds.Dy() // do not upscale image imgMaxW := maxWidth if imgMaxW == 0 || imgMaxW > srcW { imgMaxW = srcW } imgMaxH := maxHeight if imgMaxH == 0 || imgMaxH > srcH { imgMaxH = srcH } resized := imaging.Fit(src, imgMaxW, imgMaxH, imaging.Lanczos) dstBounds := resized.Bounds() resultW := dstBounds.Dx() resultH := dstBounds.Dy() tmpFile, err := ioutil.TempFile(os.TempDir(), "Goptimized-") if err != nil { fmt.Printf("Error: cannot create temporary file: %v\n", err) return } defer os.Remove(tmpFile.Name()) switch imgType := format.String(); imgType { case "JPEG": err = jpeg.Encode(tmpFile, resized, &jpeg.Options{Quality: quality}) case "PNG": err = png.Encode(tmpFile, resized) case "GIF": err = gif.Encode(tmpFile, resized, nil) case "TIFF": err = tiff.Encode(tmpFile, resized, nil) case "BMP": err = bmp.Encode(tmpFile, resized) default: fmt.Printf("Error: unsupported file type (%s)\n", file) return } if err != nil { fmt.Printf("Error saving output file: %v\n", err) return } // get the temporary filename before closing tmpFilename := tmpFile.Name() // immediately close the temp file to release pointers // so we can modify it with system processes tmpFile.Close() // run through optimizers if format.String() == "JPEG" { // run one or the other, running both has no advantage if jpegtran != "" { RunOptimizer(tmpFilename, true, jpegtran, "-optimize", "-outfile") } else if jpegoptim != "" { RunOptimizer(tmpFilename, false, jpegoptim, "-f", "-s", "-o") } } else if format.String() == "PNG" { if pngquant != "" { RunOptimizer(tmpFilename, true, pngquant, "-f", "--output") } if optipng != "" { RunOptimizer(tmpFilename, true, optipng, "-out") } } else if format.String() == "GIF" && gifsicle != "" { RunOptimizer(tmpFilename, true, gifsicle, "-o") } // re-open modified temporary file tmpFile, err = os.Open(tmpFilename) if err != nil { fmt.Printf("Error reopening temporary file: %v\n", err) return } defer tmpFile.Close() // get th eoriginal file stats srcStat, _ := os.Stat(file) srcSize := srcStat.Size() // get the optimized file stats dstStat, _ := tmpFile.Stat() dstSize := dstStat.Size() // get the original modification time for later mtime := srcStat.ModTime() atime := mtime // use mtime as we cannot get atime // calculate saved percent savedPercent := 100 - math.Round(float64(dstSize)/float64(srcSize)*100) if savedPercent > 0 { // (over)write the file - not all filesystems support // cross-filesystem moving so we overwrite the original out, err := os.Create(dstFile) if err != nil { fmt.Printf("Error opening original file: %v\n", err) return } defer out.Close() if _, err := io.Copy(out, tmpFile); err != nil { fmt.Printf("Error overwriting original file: %v\n", err) return } if preserveModTimes { // transfer original modification times if err := os.Chtimes(dstFile, atime, mtime); err != nil { fmt.Printf("Error setting file timestamp: %v\n", err) } } fmt.Printf("Goptimized %s (%dx%d %s > %s %v%%)\n", dstFile, resultW, resultH, ByteCountSI(srcSize), ByteCountSI(dstSize), savedPercent) } else { // if the output directory is not the same, // then write a copy of the original file if outputDir != "" { out, err := os.Create(dstFile) if err != nil { fmt.Printf("Error opening original file: %v\n", err) return } defer out.Close() orig, _ := os.Open(file) defer orig.Close() if _, err := io.Copy(out, orig); err != nil { fmt.Printf("Error ovewriting original file: %v\n", err) return } if preserveModTimes { // transfer original modification times if err := os.Chtimes(dstFile, atime, mtime); err != nil { fmt.Printf("Error setting file timestamp: %v\n", err) } } fmt.Printf("Copied %s (%dx%d %s %v%%)\n", dstFile, srcW, srcH, ByteCountSI(srcSize), 0) } else { // we didn't actually change anything fmt.Printf("Skipped %s (%dx%d %s %v%%)\n", dstFile, srcW, srcH, ByteCountSI(srcSize), 0) } } } // RunOptimizer will run the specified command on a copy of the temporary file, // and overwrite it if the output is smaller than the original func RunOptimizer(src string, outFileArg bool, args ...string) { // create a new temp file tmpFile, err := ioutil.TempFile(os.TempDir(), "Goptimized-") if err != nil { fmt.Printf("Cannot create temporary file: %v\n", err) return } defer os.Remove(tmpFile.Name()) source, err := os.Open(src) if err != nil { fmt.Printf("Cannot open temporary file: %v\n", err) return } defer source.Close() if _, err := io.Copy(tmpFile, source); err != nil { fmt.Printf("Cannot copy source file: %v\n", err) return } // add the filename to the args args = append(args, tmpFile.Name()) if outFileArg { // most commands require a second filename arg to overwrite the original args = append(args, tmpFile.Name()) } // execute the command cmd := exec.Command(args[0], args[1:]...) if err := cmd.Run(); err != nil { fmt.Printf("%s: %v\n", args[0], err) return } tmpFilename := tmpFile.Name() srcStat, _ := source.Stat() srcSize := srcStat.Size() dstStat, _ := os.Stat(tmpFilename) dstSize := dstStat.Size() // ensure file pointers are closed before renaming tmpFile.Close() source.Close() if dstSize < srcSize { if err := os.Rename(tmpFilename, src); err != nil { fmt.Printf("Error renaming file: %v\n", err) return } } } // ByteCountSI returns a human readable size from int64 bytes func ByteCountSI(b int64) string { const unit = 1000 if b < unit { return fmt.Sprintf("%dB", b) } div, exp := int64(unit), 0 for n := b / unit; n >= unit; n /= unit { div *= unit exp++ } return fmt.Sprintf("%.1f%cB", float64(b)/float64(div), "kMGTPE"[exp]) } // IsGIFAnimated will return an error if the GIF file has more than 1 frame func IsGIFAnimated(gifFile string) error { file, _ := os.Open(gifFile) defer file.Close() g, err := gif.DecodeAll(file) if err != nil { return err } // Single frame = OK if len(g.Image) == 1 { return nil } return fmt.Errorf("Animated gif") }