package utils import ( "errors" "image" "image/gif" "image/jpeg" "image/png" "io" "os" "github.com/nfnt/resize" "golang.org/x/image/bmp" ) func GenSmallImage(src, dst string) error { fIn, _ := os.Open(src) defer fIn.Close() fOut, _ := os.Create(dst) defer fOut.Close() if err := scale(fIn, fOut, 0, 0, 0); err != nil { return err } return nil } func scale(in io.Reader, out io.Writer, width, height, quality int) error { origin, fm, err := image.Decode(in) if err != nil { return err } if width == 0 || height == 0 { width = origin.Bounds().Max.X / 2 height = origin.Bounds().Max.Y / 2 } if quality == 0 { quality = 25 } canvas := resize.Thumbnail(uint(width), uint(height), origin, resize.Lanczos3) switch fm { case "jpeg": return jpeg.Encode(out, canvas, &jpeg.Options{quality}) case "png": return png.Encode(out, canvas) case "gif": return gif.Encode(out, canvas, &gif.Options{}) case "bmp": return bmp.Encode(out, canvas) default: return errors.New("ERROR FORMAT") } }