func Decode(r io.Reader) (img image.Image, err error) {
var dec Decoder
var t tiff.TIFF
if t, err = tiff.Parse(tiff.NewReadAtReadSeeker(r), nil, nil); err != nil {
return
}
if dec, err = getDecoder(t); err != nil {
return
}
return dec.Image()
}
func DecodeConfig(r io.Reader) (cfg image.Config, err error) {
var dec Decoder
var t tiff.TIFF
if t, err = tiff.Parse(tiff.NewReadAtReadSeeker(r), nil, nil); err != nil {
return
}
if dec, err = getDecoder(t); err != nil {
return
}
return dec.Config()
}
func Parse(r io.Reader) (eIFD, gIFD, ioIFD tiff.IFD, err error) {
rars := tiff.NewReadAtReadSeeker(r)
var two [2]byte
if _, err = rars.Read(two[:]); err != nil {
return
}
if _, err = rars.Seek(0, 0); err != nil {
return
}
switch string(two[:]) {
case "MM", "II": // likely a tiff
var t tiff.TIFF
if t, err = tiff.Parse(rars, nil, nil); err != nil {
return
}
for _, tIFD := range t.IFDs() {
if tIFD.HasField(ExifIFDTagID) {
eFld := tIFD.GetField(ExifIFDTagID)
offset := eFld.Type().Valuer()(eFld.Value().Bytes(), eFld.Value().Order()).Uint()
if eIFD, err = tiff.ParseIFD(t.R(), offset, ExifTagSpace, nil); err != nil {
return
}
if tIFD.HasField(GPSIFDTagID) {
gFld := tIFD.GetField(GPSIFDTagID)
offset = gFld.Type().Valuer()(gFld.Value().Bytes(), gFld.Value().Order()).Uint()
if gIFD, err = tiff.ParseIFD(t.R(), offset, GPSTagSpace, nil); err != nil {
log.Printf("exif: GPS IFD found, but had trouble retrieving it from offset %d: %v\n", offset, err)
}
}
if tIFD.HasField(InteroperabilityIFDTagID) {
ioFld := tIFD.GetField(InteroperabilityIFDTagID)
offset = ioFld.Type().Valuer()(ioFld.Value().Bytes(), ioFld.Value().Order()).Uint()
if ioIFD, err = tiff.ParseIFD(t.R(), offset, IOPTagSpace, nil); err != nil {
log.Printf("exif: IOP IFD found, but had trouble retrieving it from offset %d: %v\n", offset, err)
}
}
return
}
}
err = fmt.Errorf("exif: no exif ifd found in tiff")
return
case "\xff\xd8": // likely a jpeg
err = fmt.Errorf("exif: still working on jpeg support")
return
}
// Anything else is currently unsupported.
err = fmt.Errorf("exif: unsupported header: %q", two[:])
return
}