public void ReadTag(ushort tag, ExifHeader headerType, ExifPhoto photo)
{
var currentPos = _jpegFileReader.BaseStream.Position;
var fieldtype = (ExifFieldType)_binaryReader.ReadUInt16();
var length = _binaryReader.ReadUInt32();
var value = _binaryReader.ReadUInt32();
switch (fieldtype)
{
case ExifFieldType.AsciiStrings:
SeekToTiffHeaderRelativeOffset(value);
photo.SetMatchingProperty(tag, headerType, _binaryReader.ReadString((int)length));
break;
case ExifFieldType.UnsignedRational:
SeekToTiffHeaderRelativeOffset(value);
photo.SetMatchingProperty(tag, headerType, _binaryReader.ReadUnsignedRational());
break;
case ExifFieldType.UnsignedLong:
photo.SetMatchingProperty(tag, headerType, value);
break;
}
_jpegFileReader.BaseStream.Seek(currentPos + 2 + 4 + 4, SeekOrigin.Begin);
}
public void ReadTag(ushort tag, ExifHeader headerType, ExifPhoto photo)
{
var currentPos = _jpegFileReader.BaseStream.Position;
var fieldtype = (ExifFieldType)_binaryReader.ReadUInt16();
var length = _binaryReader.ReadUInt32();
var value = _binaryReader.ReadUInt32();
switch (fieldtype) {
case ExifFieldType.AsciiStrings:
SeekToTiffHeaderRelativeOffset(value);
photo.SetMatchingProperty(tag, headerType, _binaryReader.ReadString((int)length));
break;
case ExifFieldType.UnsignedRational:
SeekToTiffHeaderRelativeOffset(value);
photo.SetMatchingProperty(tag, headerType, _binaryReader.ReadUnsignedRational());
break;
case ExifFieldType.UnsignedLong:
photo.SetMatchingProperty(tag, headerType, value);
break;
}
_jpegFileReader.BaseStream.Seek(currentPos + 2 + 4 + 4, SeekOrigin.Begin);
}
public void ReadIFDHeader(ExifHeader headerType, uint headerPosition, ExifPhoto photo)
{
SeekToTiffHeaderRelativeOffset(headerPosition);
var numberOfTags = _binaryReader.ReadUInt16();
for (var i = 0; i < numberOfTags; i++) {
var tag = _binaryReader.ReadUInt16();
if (ExifPhoto.HasMatchingProperty(tag, headerType)) {
ReadTag(tag, headerType, photo);
if (!photo.HasUnsetProperties(headerType)) break;
} else
MoveToTheNextTag();
}
}
public ExifPhoto GetPhotoInfo()
{
var fileHeader = _jpegFileReader.ReadBytes(2);
if (!IsJpeg(fileHeader))
{
throw new InvalidDataException("File is not a recognisable jpeg file");
}
var nextHeader = _jpegFileReader.ReadBytes(2);
if (!IsExif(nextHeader))
{
if (!IsJfif(nextHeader))
{
throw new InvalidDataException("File does not start with JPEG Exif header");
}
var jfifLength = _binaryReader.ReadUInt16();
_jpegFileReader.BaseStream.Seek(jfifLength - 2, SeekOrigin.Current);
nextHeader = _jpegFileReader.ReadBytes(2);
if (!IsExif(nextHeader))
{
throw new InvalidDataException("Could not find Exif header");
}
TiffHeaderOffset = _jpegFileReader.BaseStream.Position + 8;
}
if (!IsBigEndian())
{
_binaryReader = new LittleEndianBinaryReader(_jpegFileReader);
}
var photo = new ExifPhoto();
ReadIFDHeader(ExifHeader.IFD0, 8, photo);
if (photo.SubIFDPosition == 0)
{
throw new InvalidDataException("Have not found ExifSubIdTag inside the file");
}
ReadIFDHeader(ExifHeader.SubIFD, photo.SubIFDPosition, photo);
if (photo.Manufacturer == null || photo.Model == null)
{
throw new InvalidDataException("Could not read photo manufacturer or model from the Exif header");
}
return(photo);
}
public void ReadIFDHeader(ExifHeader headerType, uint headerPosition, ExifPhoto photo)
{
SeekToTiffHeaderRelativeOffset(headerPosition);
var numberOfTags = _binaryReader.ReadUInt16();
for (var i = 0; i < numberOfTags; i++)
{
var tag = _binaryReader.ReadUInt16();
if (ExifPhoto.HasMatchingProperty(tag, headerType))
{
ReadTag(tag, headerType, photo);
if (!photo.HasUnsetProperties(headerType))
{
break;
}
}
else
{
MoveToTheNextTag();
}
}
}
private void AddFocalLength(ExifPhoto photo)
{
var manufacturerElement = _focalLengths.GetOrAdd(photo.Manufacturer, new ConcurrentDictionary<string, ConcurrentDictionary<decimal, int>>());
var modelElement = manufacturerElement.GetOrAdd(photo.Model, new ConcurrentDictionary<decimal, int>());
var focalLengthElement = modelElement.AddOrUpdate(photo.FocalLength, 1, (x, y) => y + 1);
}
public ExifPhoto GetPhotoInfo()
{
var fileHeader = _jpegFileReader.ReadBytes(2);
if (!IsJpeg(fileHeader)) throw new InvalidDataException("File is not a recognisable jpeg file");
var nextHeader = _jpegFileReader.ReadBytes(2);
if (!IsExif(nextHeader)) {
if (!IsJfif(nextHeader))
throw new InvalidDataException("File does not start with JPEG Exif header");
var jfifLength = _binaryReader.ReadUInt16();
_jpegFileReader.BaseStream.Seek(jfifLength - 2, SeekOrigin.Current);
nextHeader = _jpegFileReader.ReadBytes(2);
if (!IsExif(nextHeader)) throw new InvalidDataException("Could not find Exif header");
TiffHeaderOffset = _jpegFileReader.BaseStream.Position + 8;
}
if (!IsBigEndian()) _binaryReader = new LittleEndianBinaryReader(_jpegFileReader);
var photo = new ExifPhoto();
ReadIFDHeader(ExifHeader.IFD0, 8, photo);
if (photo.SubIFDPosition == 0)
throw new InvalidDataException("Have not found ExifSubIdTag inside the file");
ReadIFDHeader(ExifHeader.SubIFD, photo.SubIFDPosition, photo);
if (photo.Manufacturer == null || photo.Model == null)
throw new InvalidDataException("Could not read photo manufacturer or model from the Exif header");
return photo;
}
