private void WriteIFD(MemoryStream stream, Dictionary <ExifTag, ExifProperty> ifd, IFD ifdtype, long tiffoffset, bool preserveMakerNote)
{
BitConverterEx conv = new BitConverterEx(BitConverterEx.SystemByteOrder, ByteOrder);
// Create a queue of fields to write
Queue <ExifProperty> fieldqueue = new Queue <ExifProperty>();
foreach (ExifProperty prop in ifd.Values)
{
if (prop.Tag != ExifTag.MakerNote)
{
fieldqueue.Enqueue(prop);
}
}
// Push the maker note data to the end
if (ifd.ContainsKey(ExifTag.MakerNote))
{
fieldqueue.Enqueue(ifd[ExifTag.MakerNote]);
}
// Offset to start of field data from start of TIFF header
uint dataoffset = (uint)(2 + ifd.Count * 12 + 4 + stream.Position - tiffoffset);
uint currentdataoffset = dataoffset;
long absolutedataoffset = stream.Position + (2 + ifd.Count * 12 + 4);
bool makernotewritten = false;
// Field count
stream.Write(conv.GetBytes((ushort)ifd.Count), 0, 2);
// Fields
while (fieldqueue.Count != 0)
{
ExifProperty field = fieldqueue.Dequeue();
ExifInterOperability interop = field.Interoperability;
uint fillerbytecount = 0;
// Try to preserve the makernote data offset
if (!makernotewritten &&
!makerNoteProcessed &&
makerNoteOffset != 0 &&
ifdtype == IFD.EXIF &&
field.Tag != ExifTag.MakerNote &&
interop.Data.Length > 4 &&
currentdataoffset + interop.Data.Length > makerNoteOffset &&
ifd.ContainsKey(ExifTag.MakerNote))
{
// Delay writing this field until we write makernote data
fieldqueue.Enqueue(field);
continue;
}
else if (field.Tag == ExifTag.MakerNote)
{
makernotewritten = true;
// We may need to write filler bytes to preserve maker note offset
if (preserveMakerNote && !makerNoteProcessed && (makerNoteOffset > currentdataoffset))
{
fillerbytecount = makerNoteOffset - currentdataoffset;
}
else
{
fillerbytecount = 0;
}
}
// Tag
stream.Write(conv.GetBytes(interop.TagID), 0, 2);
// Type
stream.Write(conv.GetBytes(interop.TypeID), 0, 2);
// Count
stream.Write(conv.GetBytes(interop.Count), 0, 4);
// Field data
byte[] data = interop.Data;
if (ByteOrder != BitConverterEx.SystemByteOrder &&
(interop.TypeID == 3 || interop.TypeID == 4 || interop.TypeID == 9 ||
interop.TypeID == 5 || interop.TypeID == 10))
{
int vlen = 4;
if (interop.TypeID == 3)
{
vlen = 2;
}
int n = data.Length / vlen;
for (int i = 0; i < n; i++)
{
Array.Reverse(data, i * vlen, vlen);
}
}
// Fields containing offsets to other IFDs
// Just store their offets, we will write the values later on when we know the lengths of IFDs
if (ifdtype == IFD.Zeroth && interop.TagID == 0x8769)
{
exifIFDFieldOffset = stream.Position;
}
else if (ifdtype == IFD.Zeroth && interop.TagID == 0x8825)
{
gpsIFDFieldOffset = stream.Position;
}
else if (ifdtype == IFD.EXIF && interop.TagID == 0xa005)
{
interopIFDFieldOffset = stream.Position;
}
else if (ifdtype == IFD.First && interop.TagID == 0x201)
{
thumbOffsetLocation = stream.Position;
}
else if (ifdtype == IFD.First && interop.TagID == 0x202)
{
thumbSizeLocation = stream.Position;
}
// Write 4 byte field value or field data
if (data.Length <= 4)
{
stream.Write(data, 0, data.Length);
for (int i = data.Length; i < 4; i++)
{
stream.WriteByte(0);
}
}
else
{
// Pointer to data area relative to TIFF header
stream.Write(conv.GetBytes(currentdataoffset + fillerbytecount), 0, 4);
// Actual data
long currentoffset = stream.Position;
stream.Seek(absolutedataoffset, SeekOrigin.Begin);
// Write filler bytes
for (int i = 0; i < fillerbytecount; i++)
{
stream.WriteByte(0xFF);
}
stream.Write(data, 0, data.Length);
stream.Seek(currentoffset, SeekOrigin.Begin);
// Increment pointers
currentdataoffset += fillerbytecount + (uint)data.Length;
absolutedataoffset += fillerbytecount + data.Length;
}
}
// Offset to 1st IFD
// We will write zeros for now. This will be filled after we write all IFDs
if (ifdtype == IFD.Zeroth)
{
firstIFDFieldOffset = stream.Position;
}
stream.Write(new byte[] { 0, 0, 0, 0 }, 0, 4);
// Seek to end of IFD
stream.Seek(absolutedataoffset, SeekOrigin.Begin);
// Write thumbnail data
if (ifdtype == IFD.First)
{
if (Thumbnail != null)
{
MemoryStream ts = new MemoryStream();
Thumbnail.Save(ts);
ts.Close();
byte[] thumb = ts.ToArray();
thumbOffsetValue = (uint)(stream.Position - tiffoffset);
thumbSizeValue = (uint)thumb.Length;
stream.Write(thumb, 0, thumb.Length);
ts.Dispose();
}
else
{
thumbOffsetValue = 0;
thumbSizeValue = 0;
}
}
}
public ExifPropertyDescriptor(ExifProperty property)
: base(property.Name, new Attribute[] { new BrowsableAttribute(true) })
{
linkedProperty = property;
originalValue = property.Value;
}
/// <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);
}
}
}
}
}