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