package images import ( "bytes" "errors" "image" "image/gif" "image/jpeg" "image/png" "io" "io/ioutil" "net/http" "os" "time" "golang.org/x/image/webp" "github.com/ethereum/go-ethereum/log" ) func Decode(fileName string) (image.Image, error) { file, err := os.Open(fileName) if err != nil { return nil, err } defer file.Close() fb, err := prepareFileForDecode(file) if err != nil { return nil, err } return DecodeImageData(fb, file) } func DecodeFromURL(path string) (image.Image, error) { client := http.Client{ Timeout: 5 * time.Second, } res, err := client.Get(path) if err != nil { return nil, err } defer func() { if err := res.Body.Close(); err != nil { log.Error("failed to close profile pic http request body", "err", err) } }() if res.StatusCode >= 400 { return nil, errors.New(http.StatusText(res.StatusCode)) } bodyBytes, err := ioutil.ReadAll(res.Body) if err != nil { return nil, err } return DecodeImageData(bodyBytes, bytes.NewReader(bodyBytes)) } func prepareFileForDecode(file *os.File) ([]byte, error) { // Read the first 14 bytes, used for performing image type checks before parsing the image data fb := make([]byte, 14) _, err := file.Read(fb) if err != nil { return nil, err } // Reset the read cursor _, err = file.Seek(0, 0) if err != nil { return nil, err } return fb, nil } func DecodeImageData(buf []byte, r io.Reader) (img image.Image, err error) { switch GetType(buf) { case JPEG: img, err = jpeg.Decode(r) case PNG: img, err = png.Decode(r) case GIF: img, err = gif.Decode(r) case WEBP: img, err = webp.Decode(r) case UNKNOWN: fallthrough default: return nil, errors.New("unsupported file type") } if err != nil { return nil, err } return img, nil } func GetType(buf []byte) ImageType { switch { case IsJpeg(buf): return JPEG case IsPng(buf): return PNG case IsGif(buf): return GIF case IsWebp(buf): return WEBP default: return UNKNOWN } } func GetMimeType(buf []byte) (string, error) { switch { case IsJpeg(buf): return "jpeg", nil case IsPng(buf): return "png", nil case IsGif(buf): return "gif", nil case IsWebp(buf): return "webp", nil default: return "", errors.New("image format not supported") } } func IsJpeg(buf []byte) bool { return len(buf) > 2 && buf[0] == 0xFF && buf[1] == 0xD8 && buf[2] == 0xFF } func IsPng(buf []byte) bool { return len(buf) > 3 && buf[0] == 0x89 && buf[1] == 0x50 && buf[2] == 0x4E && buf[3] == 0x47 } func IsGif(buf []byte) bool { return len(buf) > 2 && buf[0] == 0x47 && buf[1] == 0x49 && buf[2] == 0x46 } func IsWebp(buf []byte) bool { return len(buf) > 11 && buf[8] == 0x57 && buf[9] == 0x45 && buf[10] == 0x42 && buf[11] == 0x50 } func GetImageDimensions(imgBytes []byte) (int, int, error) { // Decode image bytes img, _, err := image.Decode(bytes.NewReader(imgBytes)) if err != nil { return 0, 0, err } // Get the image dimensions bounds := img.Bounds() width := bounds.Max.X - bounds.Min.X height := bounds.Max.Y - bounds.Min.Y return width, height, nil }