/// <summary>
/// Returns a <see cref="ImageFileDirectory"/> initialized from the given byte data.
/// </summary>
/// <param name="data">The data.</param>
/// <param name="offset">The offset into <paramref name="data"/>.</param>
/// <param name="byteOrder">The byte order of <paramref name="data"/>.</param>
/// <returns>A <see cref="ImageFileDirectory"/> initialized from the given byte data.</returns>
public static ImageFileDirectory FromBytes(byte[] data, uint offset, BitConverterEx.ByteOrder byteOrder)
{
ImageFileDirectory ifd = new ImageFileDirectory();
BitConverterEx conv = new BitConverterEx(byteOrder, BitConverterEx.SystemByteOrder);
List <uint> stripOffsets = new List <uint>();
List <uint> stripLengths = new List <uint>();
// Count
ushort fieldcount = conv.ToUInt16(data, offset);
// Read fields
for (uint i = 0; i < fieldcount; i++)
{
uint fieldoffset = offset + 2 + 12 * i;
ImageFileDirectoryEntry field = ImageFileDirectoryEntry.FromBytes(data, fieldoffset, byteOrder);
ifd.Fields.Add(field);
// Read strip offsets
if (field.Tag == 273)
{
int baselen = field.Data.Length / (int)field.Count;
for (uint j = 0; j < field.Count; j++)
{
byte[] val = new byte[baselen];
Array.Copy(field.Data, j * baselen, val, 0, baselen);
uint stripOffset = (field.Type == 3 ? (uint)BitConverter.ToUInt16(val, 0) : BitConverter.ToUInt32(val, 0));
stripOffsets.Add(stripOffset);
}
}
// Read strip lengths
if (field.Tag == 279)
{
int baselen = field.Data.Length / (int)field.Count;
for (uint j = 0; j < field.Count; j++)
{
byte[] val = new byte[baselen];
Array.Copy(field.Data, j * baselen, val, 0, baselen);
uint stripLength = (field.Type == 3 ? (uint)BitConverter.ToUInt16(val, 0) : BitConverter.ToUInt32(val, 0));
stripLengths.Add(stripLength);
}
}
}
// Save strips
if (stripOffsets.Count != stripLengths.Count)
{
throw new NotValidTIFFileException();
}
for (int i = 0; i < stripOffsets.Count; i++)
{
ifd.Strips.Add(new TIFFStrip(data, stripOffsets[i], stripLengths[i]));
}
// Offset to next ifd
ifd.NextIFDOffset = conv.ToUInt32(data, offset + 2 + 12 * fieldcount);
return(ifd);
}
/// <summary>
/// Returns a <see cref="ImageFileDirectoryEntry"/> initialized from the given byte data.
/// </summary>
/// <param name="data">The data.</param>
/// <param name="offset">The offset into <paramref name="data"/>.</param>
/// <param name="byteOrder">The byte order of <paramref name="data"/>.</param>
/// <returns>A <see cref="ImageFileDirectoryEntry"/> initialized from the given byte data.</returns>
public static ImageFileDirectoryEntry FromBytes(byte[] data, uint offset, BitConverterEx.ByteOrder byteOrder)
{
// Tag ID
ushort tag = BitConverterEx.ToUInt16(data, offset, byteOrder, BitConverterEx.SystemByteOrder);
// Tag Type
ushort type = BitConverterEx.ToUInt16(data, offset + 2, byteOrder, BitConverterEx.SystemByteOrder);
// Count of Type
uint count = BitConverterEx.ToUInt32(data, offset + 4, byteOrder, BitConverterEx.SystemByteOrder);
// Field value or offset to field data
byte[] value = new byte[4];
Array.Copy(data, offset + 8, value, 0, 4);
// Calculate the bytes we need to read
uint baselength = GetBaseLength(type);
uint totallength = count * baselength;
// If field value does not fit in 4 bytes
// the value field is an offset to the actual
// field value
if (totallength > 4)
{
uint dataoffset = BitConverterEx.ToUInt32(value, 0, byteOrder, BitConverterEx.SystemByteOrder);
value = new byte[totallength];
Array.Copy(data, dataoffset, value, 0, totallength);
}
// Reverse array order if byte orders are different
if (byteOrder != BitConverterEx.SystemByteOrder)
{
for (uint i = 0; i < count; i++)
{
byte[] val = new byte[baselength];
Array.Copy(value, i * baselength, val, 0, baselength);
Array.Reverse(val);
Array.Copy(val, 0, value, i * baselength, baselength);
}
}
return(new ImageFileDirectoryEntry(tag, type, count, value));
}
/// <summary>
/// Creates an ExifProperty from the given interoperability parameters.
/// </summary>
/// <param name="tag">The tag id of the exif property.</param>
/// <param name="type">The type id of the exif property.</param>
/// <param name="count">Byte or component count.</param>
/// <param name="value">Field data as an array of bytes.</param>
/// <param name="byteOrder">Byte order of value.</param>
/// <param name="ifd">IFD section containing this propery.</param>
/// <param name="encoding">The encoding to be used for text metadata when the source encoding is unknown.</param>
/// <returns>an ExifProperty initialized from the interoperability parameters.</returns>
public static ExifProperty Get(ushort tag, ushort type, uint count, byte[] value, BitConverterEx.ByteOrder byteOrder, IFD ifd, Encoding encoding)
{
BitConverterEx conv = new BitConverterEx(byteOrder, BitConverterEx.SystemByteOrder);
// Find the exif tag corresponding to given tag id
ExifTag etag = ExifTagFactory.GetExifTag(ifd, tag);
if (ifd == IFD.Zeroth)
{
if (tag == 0x103) // Compression
{
return(new ExifEnumProperty <Compression>(ExifTag.Compression, (Compression)conv.ToUInt16(value, 0)));
}
else if (tag == 0x106) // PhotometricInterpretation
{
return(new ExifEnumProperty <PhotometricInterpretation>(ExifTag.PhotometricInterpretation, (PhotometricInterpretation)conv.ToUInt16(value, 0)));
}
else if (tag == 0x112) // Orientation
{
return(new ExifEnumProperty <Orientation>(ExifTag.Orientation, (Orientation)conv.ToUInt16(value, 0)));
}
else if (tag == 0x11c) // PlanarConfiguration
{
return(new ExifEnumProperty <PlanarConfiguration>(ExifTag.PlanarConfiguration, (PlanarConfiguration)conv.ToUInt16(value, 0)));
}
else if (tag == 0x213) // YCbCrPositioning
{
return(new ExifEnumProperty <YCbCrPositioning>(ExifTag.YCbCrPositioning, (YCbCrPositioning)conv.ToUInt16(value, 0)));
}
else if (tag == 0x128) // ResolutionUnit
{
return(new ExifEnumProperty <ResolutionUnit>(ExifTag.ResolutionUnit, (ResolutionUnit)conv.ToUInt16(value, 0)));
}
else if (tag == 0x132) // DateTime
{
return(new ExifDateTime(ExifTag.DateTime, ExifBitConverter.ToDateTime(value)));
}
else if (tag == 0x9c9b || tag == 0x9c9c || // Windows tags
tag == 0x9c9d || tag == 0x9c9e || tag == 0x9c9f)
{
return(new WindowsByteString(etag, Encoding.Unicode.GetString(value).TrimEnd('\0')));
}
}
else if (ifd == IFD.EXIF)
{
if (tag == 0x9000) // ExifVersion
{
return(new ExifVersion(ExifTag.ExifVersion, ExifBitConverter.ToAscii(value, Encoding.ASCII)));
}
else if (tag == 0xa000) // FlashpixVersion
{
return(new ExifVersion(ExifTag.FlashpixVersion, ExifBitConverter.ToAscii(value, Encoding.ASCII)));
}
else if (tag == 0xa001) // ColorSpace
{
return(new ExifEnumProperty <ColorSpace>(ExifTag.ColorSpace, (ColorSpace)conv.ToUInt16(value, 0)));
}
else if (tag == 0x9286) // UserComment
{
// Default to ASCII
Encoding enc = Encoding.ASCII;
bool hasenc;
if (value.Length < 8)
{
hasenc = false;
}
else
{
hasenc = true;
string encstr = enc.GetString(value, 0, 8);
if (string.Compare(encstr, "ASCII\0\0\0", StringComparison.OrdinalIgnoreCase) == 0)
{
enc = Encoding.ASCII;
}
else if (string.Compare(encstr, "JIS\0\0\0\0\0", StringComparison.OrdinalIgnoreCase) == 0)
{
enc = Encoding.GetEncoding("Japanese (JIS 0208-1990 and 0212-1990)");
}
else if (string.Compare(encstr, "Unicode\0", StringComparison.OrdinalIgnoreCase) == 0)
{
enc = Encoding.Unicode;
}
else
{
hasenc = false;
}
}
string val = (hasenc ? enc.GetString(value, 8, value.Length - 8) : enc.GetString(value)).Trim('\0');
return(new ExifEncodedString(ExifTag.UserComment, val, enc));
}
else if (tag == 0x9003) // DateTimeOriginal
{
return(new ExifDateTime(ExifTag.DateTimeOriginal, ExifBitConverter.ToDateTime(value)));
}
else if (tag == 0x9004) // DateTimeDigitized
{
return(new ExifDateTime(ExifTag.DateTimeDigitized, ExifBitConverter.ToDateTime(value)));
}
else if (tag == 0x8822) // ExposureProgram
{
return(new ExifEnumProperty <ExposureProgram>(ExifTag.ExposureProgram, (ExposureProgram)conv.ToUInt16(value, 0)));
}
else if (tag == 0x9207) // MeteringMode
{
return(new ExifEnumProperty <MeteringMode>(ExifTag.MeteringMode, (MeteringMode)conv.ToUInt16(value, 0)));
}
else if (tag == 0x9208) // LightSource
{
return(new ExifEnumProperty <LightSource>(ExifTag.LightSource, (LightSource)conv.ToUInt16(value, 0)));
}
else if (tag == 0x9209) // Flash
{
return(new ExifEnumProperty <Flash>(ExifTag.Flash, (Flash)conv.ToUInt16(value, 0), true));
}
else if (tag == 0x9214) // SubjectArea
{
if (count == 3)
{
return(new ExifCircularSubjectArea(ExifTag.SubjectArea, ExifBitConverter.ToUShortArray(value, (int)count, byteOrder)));
}
else if (count == 4)
{
return(new ExifRectangularSubjectArea(ExifTag.SubjectArea, ExifBitConverter.ToUShortArray(value, (int)count, byteOrder)));
}
else // count == 2
{
return(new ExifPointSubjectArea(ExifTag.SubjectArea, ExifBitConverter.ToUShortArray(value, (int)count, byteOrder)));
}
}
else if (tag == 0xa210) // FocalPlaneResolutionUnit
{
return(new ExifEnumProperty <ResolutionUnit>(ExifTag.FocalPlaneResolutionUnit, (ResolutionUnit)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa214) // SubjectLocation
{
return(new ExifPointSubjectArea(ExifTag.SubjectLocation, ExifBitConverter.ToUShortArray(value, (int)count, byteOrder)));
}
else if (tag == 0xa217) // SensingMethod
{
return(new ExifEnumProperty <SensingMethod>(ExifTag.SensingMethod, (SensingMethod)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa300) // FileSource
{
return(new ExifEnumProperty <FileSource>(ExifTag.FileSource, (FileSource)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa301) // SceneType
{
return(new ExifEnumProperty <SceneType>(ExifTag.SceneType, (SceneType)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa401) // CustomRendered
{
return(new ExifEnumProperty <CustomRendered>(ExifTag.CustomRendered, (CustomRendered)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa402) // ExposureMode
{
return(new ExifEnumProperty <ExposureMode>(ExifTag.ExposureMode, (ExposureMode)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa403) // WhiteBalance
{
return(new ExifEnumProperty <WhiteBalance>(ExifTag.WhiteBalance, (WhiteBalance)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa406) // SceneCaptureType
{
return(new ExifEnumProperty <SceneCaptureType>(ExifTag.SceneCaptureType, (SceneCaptureType)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa407) // GainControl
{
return(new ExifEnumProperty <GainControl>(ExifTag.GainControl, (GainControl)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa408) // Contrast
{
return(new ExifEnumProperty <Contrast>(ExifTag.Contrast, (Contrast)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa409) // Saturation
{
return(new ExifEnumProperty <Saturation>(ExifTag.Saturation, (Saturation)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa40a) // Sharpness
{
return(new ExifEnumProperty <Sharpness>(ExifTag.Sharpness, (Sharpness)conv.ToUInt16(value, 0), true));
}
else if (tag == 0xa40c) // SubjectDistanceRange
{
return(new ExifEnumProperty <SubjectDistanceRange>(ExifTag.SubjectDistanceRange, (SubjectDistanceRange)conv.ToUInt16(value, 0), true));
}
}
else if (ifd == IFD.GPS)
{
if (tag == 0) // GPSVersionID
{
return(new ExifVersion(ExifTag.GPSVersionID, ExifBitConverter.ToString(value)));
}
else if (tag == 1) // GPSLatitudeRef
{
return(new ExifEnumProperty <GPSLatitudeRef>(ExifTag.GPSLatitudeRef, (GPSLatitudeRef)value[0]));
}
else if (tag == 2) // GPSLatitude
{
return(new GPSLatitudeLongitude(ExifTag.GPSLatitude, ExifBitConverter.ToURationalArray(value, (int)count, byteOrder)));
}
else if (tag == 3) // GPSLongitudeRef
{
return(new ExifEnumProperty <GPSLongitudeRef>(ExifTag.GPSLongitudeRef, (GPSLongitudeRef)value[0]));
}
else if (tag == 4) // GPSLongitude
{
return(new GPSLatitudeLongitude(ExifTag.GPSLongitude, ExifBitConverter.ToURationalArray(value, (int)count, byteOrder)));
}
else if (tag == 5) // GPSAltitudeRef
{
return(new ExifEnumProperty <GPSAltitudeRef>(ExifTag.GPSAltitudeRef, (GPSAltitudeRef)value[0]));
}
else if (tag == 7) // GPSTimeStamp
{
return(new GPSTimeStamp(ExifTag.GPSTimeStamp, ExifBitConverter.ToURationalArray(value, (int)count, byteOrder)));
}
else if (tag == 9) // GPSStatus
{
return(new ExifEnumProperty <GPSStatus>(ExifTag.GPSStatus, (GPSStatus)value[0]));
}
else if (tag == 10) // GPSMeasureMode
{
return(new ExifEnumProperty <GPSMeasureMode>(ExifTag.GPSMeasureMode, (GPSMeasureMode)value[0]));
}
else if (tag == 12) // GPSSpeedRef
{
return(new ExifEnumProperty <GPSSpeedRef>(ExifTag.GPSSpeedRef, (GPSSpeedRef)value[0]));
}
else if (tag == 14) // GPSTrackRef
{
return(new ExifEnumProperty <GPSDirectionRef>(ExifTag.GPSTrackRef, (GPSDirectionRef)value[0]));
}
else if (tag == 16) // GPSImgDirectionRef
{
return(new ExifEnumProperty <GPSDirectionRef>(ExifTag.GPSImgDirectionRef, (GPSDirectionRef)value[0]));
}
else if (tag == 19) // GPSDestLatitudeRef
{
return(new ExifEnumProperty <GPSLatitudeRef>(ExifTag.GPSDestLatitudeRef, (GPSLatitudeRef)value[0]));
}
else if (tag == 20) // GPSDestLatitude
{
return(new GPSLatitudeLongitude(ExifTag.GPSDestLatitude, ExifBitConverter.ToURationalArray(value, (int)count, byteOrder)));
}
else if (tag == 21) // GPSDestLongitudeRef
{
return(new ExifEnumProperty <GPSLongitudeRef>(ExifTag.GPSDestLongitudeRef, (GPSLongitudeRef)value[0]));
}
else if (tag == 22) // GPSDestLongitude
{
return(new GPSLatitudeLongitude(ExifTag.GPSDestLongitude, ExifBitConverter.ToURationalArray(value, (int)count, byteOrder)));
}
else if (tag == 23) // GPSDestBearingRef
{
return(new ExifEnumProperty <GPSDirectionRef>(ExifTag.GPSDestBearingRef, (GPSDirectionRef)value[0]));
}
else if (tag == 25) // GPSDestDistanceRef
{
return(new ExifEnumProperty <GPSDistanceRef>(ExifTag.GPSDestDistanceRef, (GPSDistanceRef)value[0]));
}
else if (tag == 29) // GPSDate
{
return(new ExifDateTime(ExifTag.GPSDateStamp, ExifBitConverter.ToDateTime(value, false)));
}
else if (tag == 30) // GPSDifferential
{
return(new ExifEnumProperty <GPSDifferential>(ExifTag.GPSDifferential, (GPSDifferential)conv.ToUInt16(value, 0)));
}
}
else if (ifd == IFD.Interop)
{
if (tag == 1) // InteroperabilityIndex
{
return(new ExifAscii(ExifTag.InteroperabilityIndex, ExifBitConverter.ToAscii(value, Encoding.ASCII), Encoding.ASCII));
}
else if (tag == 2) // InteroperabilityVersion
{
return(new ExifVersion(ExifTag.InteroperabilityVersion, ExifBitConverter.ToAscii(value, Encoding.ASCII)));
}
}
else if (ifd == IFD.First)
{
if (tag == 0x103) // Compression
{
return(new ExifEnumProperty <Compression>(ExifTag.ThumbnailCompression, (Compression)conv.ToUInt16(value, 0)));
}
else if (tag == 0x106) // PhotometricInterpretation
{
return(new ExifEnumProperty <PhotometricInterpretation>(ExifTag.ThumbnailPhotometricInterpretation, (PhotometricInterpretation)conv.ToUInt16(value, 0)));
}
else if (tag == 0x112) // Orientation
{
return(new ExifEnumProperty <Orientation>(ExifTag.ThumbnailOrientation, (Orientation)conv.ToUInt16(value, 0)));
}
else if (tag == 0x11c) // PlanarConfiguration
{
return(new ExifEnumProperty <PlanarConfiguration>(ExifTag.ThumbnailPlanarConfiguration, (PlanarConfiguration)conv.ToUInt16(value, 0)));
}
else if (tag == 0x213) // YCbCrPositioning
{
return(new ExifEnumProperty <YCbCrPositioning>(ExifTag.ThumbnailYCbCrPositioning, (YCbCrPositioning)conv.ToUInt16(value, 0)));
}
else if (tag == 0x128) // ResolutionUnit
{
return(new ExifEnumProperty <ResolutionUnit>(ExifTag.ThumbnailResolutionUnit, (ResolutionUnit)conv.ToUInt16(value, 0)));
}
else if (tag == 0x132) // DateTime
{
return(new ExifDateTime(ExifTag.ThumbnailDateTime, ExifBitConverter.ToDateTime(value)));
}
}
if (type == 1) // 1 = BYTE An 8-bit unsigned integer.
{
if (count == 1)
{
return(new ExifByte(etag, value[0]));
}
else
{
return(new ExifByteArray(etag, value));
}
}
else if (type == 2) // 2 = ASCII An 8-bit byte containing one 7-bit ASCII code.
{
return(new ExifAscii(etag, ExifBitConverter.ToAscii(value, encoding), encoding));
}
else if (type == 3) // 3 = SHORT A 16-bit (2-byte) unsigned integer.
{
if (count == 1)
{
return(new ExifUShort(etag, conv.ToUInt16(value, 0)));
}
else
{
return(new ExifUShortArray(etag, ExifBitConverter.ToUShortArray(value, (int)count, byteOrder)));
}
}
else if (type == 4) // 4 = LONG A 32-bit (4-byte) unsigned integer.
{
if (count == 1)
{
return(new ExifUInt(etag, conv.ToUInt32(value, 0)));
}
else
{
return(new ExifUIntArray(etag, ExifBitConverter.ToUIntArray(value, (int)count, byteOrder)));
}
}
else if (type == 5) // 5 = RATIONAL Two LONGs. The first LONG is the numerator and the second LONG expresses the denominator.
{
if (count == 1)
{
return(new ExifURational(etag, ExifBitConverter.ToURational(value, byteOrder)));
}
else
{
return(new ExifURationalArray(etag, ExifBitConverter.ToURationalArray(value, (int)count, byteOrder)));
}
}
else if (type == 7) // 7 = UNDEFINED An 8-bit byte that can take any value depending on the field definition.
{
return(new ExifUndefined(etag, value));
}
else if (type == 9) // 9 = SLONG A 32-bit (4-byte) signed integer (2's complement notation).
{
if (count == 1)
{
return(new ExifSInt(etag, conv.ToInt32(value, 0)));
}
else
{
return(new ExifSIntArray(etag, ExifBitConverter.ToSIntArray(value, (int)count, byteOrder)));
}
}
else if (type == 10) // 10 = SRATIONAL Two SLONGs. The first SLONG is the numerator and the second SLONG is the denominator.
{
if (count == 1)
{
return(new ExifSRational(etag, ExifBitConverter.ToSRational(value, byteOrder)));
}
else
{
return(new ExifSRationalArray(etag, ExifBitConverter.ToSRationalArray(value, (int)count, byteOrder)));
}
}
else
{
throw new ArgumentException("Unknown property type.");
}
}
/// <summary>
/// Reads the APP1 section containing Exif metadata.
/// </summary>
private void ReadExifAPP1()
{
// Find the APP1 section containing Exif metadata
exifApp1 = Sections.Find(a => (a.Marker == JPEGMarker.APP1) &&
a.Header.Length >= 6 &&
(Encoding.ASCII.GetString(a.Header, 0, 6) == "Exif\0\0"));
// If there is no APP1 section, add a new one after the last APP0 section (if any).
if (exifApp1 == null)
{
int insertionIndex = Sections.FindLastIndex(a => a.Marker == JPEGMarker.APP0);
if (insertionIndex == -1)
{
insertionIndex = 0;
}
insertionIndex++;
exifApp1 = new JPEGSection(JPEGMarker.APP1);
Sections.Insert(insertionIndex, exifApp1);
if (BitConverterEx.SystemByteOrder == BitConverterEx.ByteOrder.LittleEndian)
{
ByteOrder = BitConverterEx.ByteOrder.LittleEndian;
}
else
{
ByteOrder = BitConverterEx.ByteOrder.BigEndian;
}
return;
}
byte[] header = exifApp1.Header;
SortedList <int, IFD> ifdqueue = new SortedList <int, IFD>();
makerNoteOffset = 0;
// TIFF header
int tiffoffset = 6;
if (header[tiffoffset] == 0x49 && header[tiffoffset + 1] == 0x49)
{
ByteOrder = BitConverterEx.ByteOrder.LittleEndian;
}
else if (header[tiffoffset] == 0x4D && header[tiffoffset + 1] == 0x4D)
{
ByteOrder = BitConverterEx.ByteOrder.BigEndian;
}
else
{
throw new NotValidExifFileException();
}
// TIFF header may have a different byte order
BitConverterEx.ByteOrder tiffByteOrder = ByteOrder;
if (BitConverterEx.LittleEndian.ToUInt16(header, tiffoffset + 2) == 42)
{
tiffByteOrder = BitConverterEx.ByteOrder.LittleEndian;
}
else if (BitConverterEx.BigEndian.ToUInt16(header, tiffoffset + 2) == 42)
{
tiffByteOrder = BitConverterEx.ByteOrder.BigEndian;
}
else
{
throw new NotValidExifFileException();
}
// Offset to 0th IFD
int ifd0offset = (int)BitConverterEx.ToUInt32(header, tiffoffset + 4, tiffByteOrder, BitConverterEx.SystemByteOrder);
ifdqueue.Add(ifd0offset, IFD.Zeroth);
BitConverterEx conv = new BitConverterEx(ByteOrder, BitConverterEx.SystemByteOrder);
int thumboffset = -1;
int thumblength = 0;
int thumbtype = -1;
// Read IFDs
while (ifdqueue.Count != 0)
{
int ifdoffset = tiffoffset + ifdqueue.Keys[0];
IFD currentifd = ifdqueue.Values[0];
ifdqueue.RemoveAt(0);
// Field count
ushort fieldcount = conv.ToUInt16(header, ifdoffset);
for (short i = 0; i < fieldcount; i++)
{
// Read field info
int fieldoffset = ifdoffset + 2 + 12 * i;
ushort tag = conv.ToUInt16(header, fieldoffset);
ushort type = conv.ToUInt16(header, fieldoffset + 2);
uint count = conv.ToUInt32(header, fieldoffset + 4);
byte[] value = new byte[4];
Array.Copy(header, fieldoffset + 8, value, 0, 4);
// Fields containing offsets to other IFDs
if (currentifd == IFD.Zeroth && tag == 0x8769)
{
int exififdpointer = (int)conv.ToUInt32(value, 0);
ifdqueue.Add(exififdpointer, IFD.EXIF);
}
else if (currentifd == IFD.Zeroth && tag == 0x8825)
{
int gpsifdpointer = (int)conv.ToUInt32(value, 0);
ifdqueue.Add(gpsifdpointer, IFD.GPS);
}
else if (currentifd == IFD.EXIF && tag == 0xa005)
{
int interopifdpointer = (int)conv.ToUInt32(value, 0);
ifdqueue.Add(interopifdpointer, IFD.Interop);
}
// Save the offset to maker note data
if (currentifd == IFD.EXIF && tag == 37500)
{
makerNoteOffset = conv.ToUInt32(value, 0);
}
// Calculate the bytes we need to read
uint baselength = 0;
if (type == 1 || type == 2 || type == 7)
{
baselength = 1;
}
else if (type == 3)
{
baselength = 2;
}
else if (type == 4 || type == 9)
{
baselength = 4;
}
else if (type == 5 || type == 10)
{
baselength = 8;
}
uint totallength = count * baselength;
// If field value does not fit in 4 bytes
// the value field is an offset to the actual
// field value
int fieldposition = 0;
if (totallength > 4)
{
fieldposition = tiffoffset + (int)conv.ToUInt32(value, 0);
value = new byte[totallength];
Array.Copy(header, fieldposition, value, 0, totallength);
}
// Compressed thumbnail data
if (currentifd == IFD.First && tag == 0x201)
{
thumbtype = 0;
thumboffset = (int)conv.ToUInt32(value, 0);
}
else if (currentifd == IFD.First && tag == 0x202)
{
thumblength = (int)conv.ToUInt32(value, 0);
}
// Uncompressed thumbnail data
if (currentifd == IFD.First && tag == 0x111)
{
thumbtype = 1;
// Offset to first strip
if (type == 3)
{
thumboffset = (int)conv.ToUInt16(value, 0);
}
else
{
thumboffset = (int)conv.ToUInt32(value, 0);
}
}
else if (currentifd == IFD.First && tag == 0x117)
{
thumblength = 0;
for (int j = 0; j < count; j++)
{
if (type == 3)
{
thumblength += (int)conv.ToUInt16(value, 0);
}
else
{
thumblength += (int)conv.ToUInt32(value, 0);
}
}
}
// Create the exif property from the interop data
ExifProperty prop = ExifPropertyFactory.Get(tag, type, count, value, ByteOrder, currentifd, Encoding);
Properties.Add(prop);
}
// 1st IFD pointer
int firstifdpointer = (int)conv.ToUInt32(header, ifdoffset + 2 + 12 * fieldcount);
if (firstifdpointer != 0)
{
ifdqueue.Add(firstifdpointer, IFD.First);
}
// Read thumbnail
if (thumboffset != -1 && thumblength != 0 && Thumbnail == null)
{
if (thumbtype == 0)
{
using (MemoryStream ts = new MemoryStream(header, tiffoffset + thumboffset, thumblength))
{
Thumbnail = ImageFile.FromStream(ts);
}
}
}
}
}
/// <summary>
/// Converts the given array of bytes to a 32-bit unsigned integer.
/// </summary>
public uint ToUInt32(byte[] value, long startIndex)
{
return(BitConverterEx.ToUInt32(value, startIndex, mFrom, mTo));
}