public byte[] CreateExifBlob()
{
IFDInfo ifdInfo = BuildIFDEntries();
Dictionary <MetadataSection, IFDEntryInfo> ifdEntries = ifdInfo.IFDEntries;
byte[] exifBytes = new byte[checked ((int)ifdInfo.EXIFDataLength)];
using (MemoryStream stream = new MemoryStream(exifBytes))
using (BinaryWriter writer = new BinaryWriter(stream))
{
IFDEntryInfo imageInfo = ifdEntries[MetadataSection.Image];
IFDEntryInfo exifInfo = ifdEntries[MetadataSection.Exif];
writer.Write(TiffConstants.LittleEndianByteOrderMarker);
writer.Write(TiffConstants.Signature);
writer.Write((uint)imageInfo.StartOffset);
WriteDirectory(writer, metadata[MetadataSection.Image], imageInfo.IFDEntries, imageInfo.StartOffset);
WriteDirectory(writer, metadata[MetadataSection.Exif], exifInfo.IFDEntries, exifInfo.StartOffset);
if (ifdEntries.TryGetValue(MetadataSection.Interop, out IFDEntryInfo interopInfo))
{
WriteDirectory(writer, metadata[MetadataSection.Interop], interopInfo.IFDEntries, interopInfo.StartOffset);
}
if (ifdEntries.TryGetValue(MetadataSection.Gps, out IFDEntryInfo gpsInfo))
{
WriteDirectory(writer, metadata[MetadataSection.Gps], gpsInfo.IFDEntries, gpsInfo.StartOffset);
}
}
return(exifBytes);
}
private IFDInfo CreateIFDInfo(
IFDEntryInfo imageIFDInfo,
IFDEntryInfo exifIFDInfo,
IFDEntryInfo interopIFDInfo,
IFDEntryInfo gpsIFDInfo)
{
Dictionary <MetadataSection, IFDEntryInfo> entries = new Dictionary <MetadataSection, IFDEntryInfo>
{
{ MetadataSection.Image, imageIFDInfo },
{ MetadataSection.Exif, exifIFDInfo }
};
long dataLength = exifIFDInfo.NextAvailableOffset;
if (interopIFDInfo != null)
{
entries.Add(MetadataSection.Interop, interopIFDInfo);
dataLength = interopIFDInfo.NextAvailableOffset;
}
if (gpsIFDInfo != null)
{
entries.Add(MetadataSection.Gps, gpsIFDInfo);
dataLength = gpsIFDInfo.NextAvailableOffset;
}
return(new IFDInfo(entries, dataLength));
}
private IFDInfo CalculateSectionOffsets()
{
IFDEntryInfo imageIFDInfo = CreateIFDList(metadata[MetadataSection.Image], FirstIFDOffset);
IFDEntryInfo exifIFDInfo = CreateIFDList(metadata[MetadataSection.Exif], imageIFDInfo.NextAvailableOffset);
IFDEntryInfo interopIFDInfo = null;
IFDEntryInfo gpsIFDInfo = null;
UpdateSubIFDOffset(ref imageIFDInfo, MetadataKeys.Image.ExifTag.TagId, (uint)exifIFDInfo.StartOffset);
if (metadata.TryGetValue(MetadataSection.Interop, out Dictionary <ushort, MetadataEntry> interopSection))
{
interopIFDInfo = CreateIFDList(interopSection, exifIFDInfo.NextAvailableOffset);
UpdateSubIFDOffset(ref exifIFDInfo, MetadataKeys.Exif.InteroperabilityTag.TagId, (uint)interopIFDInfo.StartOffset);
}
if (metadata.TryGetValue(MetadataSection.Gps, out Dictionary <ushort, MetadataEntry> gpsSection))
{
long startOffset = interopIFDInfo?.NextAvailableOffset ?? exifIFDInfo.NextAvailableOffset;
gpsIFDInfo = CreateIFDList(gpsSection, startOffset);
UpdateSubIFDOffset(ref imageIFDInfo, MetadataKeys.Image.GPSTag.TagId, (uint)gpsIFDInfo.StartOffset);
}
return(CreateIFDInfo(imageIFDInfo, exifIFDInfo, interopIFDInfo, gpsIFDInfo));
}
private static void UpdateSubIFDOffset(ref IFDEntryInfo ifdInfo, ushort tagId, uint newOffset)
{
int index = ifdInfo.IFDEntries.FindIndex(i => i.Tag == tagId);
if (index != -1)
{
ifdInfo.IFDEntries[index] = new IFDEntry(tagId, TagDataType.Long, 1, newOffset);
}
}
private static IFDInfo CreateIFDInfo(
IFDEntryInfo imageIFDInfo,
IFDEntryInfo exifIFDInfo,
IFDEntryInfo interopIFDInfo,
IFDEntryInfo gpsIFDInfo)
{
Dictionary <ExifSection, IFDEntryInfo> entries = new()
{
{ ExifSection.Image, imageIFDInfo },
{ ExifSection.Photo, exifIFDInfo }
};
