private void WriteIFD(MemoryStream stream, Dictionary <ExifTag, ExifProperty> ifd, IFD ifdtype, long tiffoffset, bool preserveMakerNote) { BitConverterEx conv = new BitConverterEx(BitConverterEx.ByteOrder.System, 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) { 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) { if (interop.TypeID == 1 || interop.TypeID == 3 || interop.TypeID == 4 || interop.TypeID == 9) { Array.Reverse(data); } else if (interop.TypeID == 5 || interop.TypeID == 10) { Array.Reverse(data, 0, 4); Array.Reverse(data, 4, 4); } } // 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; } } }
/// <summary> /// Creates an ExifProperty from the given interoperability parameters. /// </summary> /// <param name="interOperability">Property data.</param> /// <param name="byteOrder">Byte order of the source data.</param> /// <param name="ifd">IFD section containing this propery.</param> /// <returns>an ExifProperty initialized from the interoperability parameters.</returns> public static ExifProperty Get(ExifInterOperability interOperability, BitConverterEx.ByteOrder byteOrder, IFD ifd) { return(Get(interOperability.TagID, interOperability.TypeID, interOperability.Count, interOperability.Data, byteOrder, ifd)); }