/// <summary>
/// Initializes a new instance of the <see cref="JPEGFile"/> class from the
/// specified data stream.
/// </summary>
/// <param name="stream">A <see cref="Sytem.IO.Stream"/> that contains image data.</param>
/// <param name="encoding">The encoding to be used for text metadata when the source encoding is unknown.</param>
protected internal TIFFFile(Stream stream, System.Text.Encoding encoding)
{
Format = ImageFileFormat.TIFF;
IFDs = new List <ImageFileDirectory>();
Encoding = encoding;
// Read the entire stream
byte[] data = Utility.GetStreamBytes(stream);
// Read the TIFF header
TIFFHeader = TIFFHeader.FromBytes(data, 0);
uint nextIFDOffset = TIFFHeader.IFDOffset;
if (nextIFDOffset == 0)
{
throw new NotValidTIFFileException("The first IFD offset is zero.");
}
// Read IFDs in order
while (nextIFDOffset != 0)
{
ImageFileDirectory ifd = ImageFileDirectory.FromBytes(data, nextIFDOffset, TIFFHeader.ByteOrder);
nextIFDOffset = ifd.NextIFDOffset;
IFDs.Add(ifd);
}
// Process IFDs
// TODO: Add support for multiple frames
foreach (ImageFileDirectoryEntry field in IFDs[0].Fields)
{
Properties.Add(ExifPropertyFactory.Get(field.Tag, field.Type, field.Count, field.Data, BitConverterEx.SystemByteOrder, IFD.Zeroth, Encoding));
}
}
/// <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);
}
}
}
}
}
