public override void Completed(RandomAccessReader reader, int tiffHeaderOffset)
{
if (_storeThumbnailBytes)
{
// after the extraction process, if we have the correct tags, we may be able to store thumbnail information
ExifThumbnailDirectory thumbnailDirectory = _metadata.GetDirectory <ExifThumbnailDirectory>();
if (thumbnailDirectory != null && thumbnailDirectory.ContainsTag(ExifThumbnailDirectory.TagThumbnailCompression))
{
int?offset = thumbnailDirectory.GetInteger(ExifThumbnailDirectory.TagThumbnailOffset);
int?length = thumbnailDirectory.GetInteger(ExifThumbnailDirectory.TagThumbnailLength);
if (offset != null && length != null)
{
try
{
sbyte[] thumbnailData = reader.GetBytes(tiffHeaderOffset + offset.Value, length.Value);
thumbnailDirectory.SetThumbnailData(thumbnailData);
}
catch (IOException ex)
{
thumbnailDirectory.AddError("Invalid thumbnail data specification: " + ex.Message);
}
}
}
}
}
private static void ExtractTiff(RandomAccessReader reader, Com.Drew.Metadata.Metadata metadata, Com.Drew.Metadata.Directory firstDirectory, int tiffHeaderOffset)
{
// this should be either "MM" or "II"
string byteOrderIdentifier = reader.GetString(tiffHeaderOffset, 2);
if ("MM".Equals(byteOrderIdentifier))
{
reader.SetMotorolaByteOrder(true);
}
else
{
if ("II".Equals(byteOrderIdentifier))
{
reader.SetMotorolaByteOrder(false);
}
else
{
firstDirectory.AddError("Unclear distinction between Motorola/Intel byte ordering: " + byteOrderIdentifier);
return;
}
}
// Check the next two values for correctness.
int tiffMarker = reader.GetUInt16(2 + tiffHeaderOffset);
int standardTiffMarker = unchecked ((int)(0x002A));
int olympusRawTiffMarker = unchecked ((int)(0x4F52));
// for ORF files
int panasonicRawTiffMarker = unchecked ((int)(0x0055));
// for RW2 files
if (tiffMarker != standardTiffMarker && tiffMarker != olympusRawTiffMarker && tiffMarker != panasonicRawTiffMarker)
{
firstDirectory.AddError("Unexpected TIFF marker after byte order identifier: 0x" + Sharpen.Extensions.ToHexString(tiffMarker));
return;
}
int firstIfdOffset = reader.GetInt32(4 + tiffHeaderOffset) + tiffHeaderOffset;
// David Ekholm sent a digital camera image that has this problem
// TODO getLength should be avoided as it causes RandomAccessStreamReader to read to the end of the stream
if (firstIfdOffset >= reader.GetLength() - 1)
{
firstDirectory.AddError("First Exif directory offset is beyond end of Exif data segment");
// First directory normally starts 14 bytes in -- try it here and catch another error in the worst case
firstIfdOffset = 14;
}
ICollection <int> processedIfdOffsets = new HashSet <int>();
ProcessIFD(firstDirectory, processedIfdOffsets, firstIfdOffset, tiffHeaderOffset, metadata, reader);
// after the extraction process, if we have the correct tags, we may be able to store thumbnail information
ExifThumbnailDirectory thumbnailDirectory = metadata.GetDirectory <ExifThumbnailDirectory>();
if (thumbnailDirectory != null && thumbnailDirectory.ContainsTag(ExifThumbnailDirectory.TagThumbnailCompression))
{
int?offset = thumbnailDirectory.GetInteger(ExifThumbnailDirectory.TagThumbnailOffset);
int?length = thumbnailDirectory.GetInteger(ExifThumbnailDirectory.TagThumbnailLength);
if (offset != null && length != null)
{
try
{
sbyte[] thumbnailData = reader.GetBytes(tiffHeaderOffset + offset.Value, length.Value);
thumbnailDirectory.SetThumbnailData(thumbnailData);
}
catch (IOException ex)
{
firstDirectory.AddError("Invalid thumbnail data specification: " + ex.Message);
}
}
}
}
