public static string GetExtendedXmpGuid(XmpPacket xmpPacket)
{
if (xmpPacket is null)
{
ExceptionUtil.ThrowArgumentNullException(nameof(xmpPacket));
}
string extendedXmpGuid = null;
XElement rdfElement = xmpPacket.Document.Descendants(RdfContainerElementName).First();
XObject hasExtendedXmpObject = FindHasExtendedXmpObject(rdfElement);
if (hasExtendedXmpObject != null)
{
if (hasExtendedXmpObject is XAttribute attribute)
{
extendedXmpGuid = attribute.Value;
}
else if (hasExtendedXmpObject is XElement element)
{
extendedXmpGuid = element.Value;
}
}
return(extendedXmpGuid);
}
public JpegXmpPackets GetXmpPackets()
{
if (!fileParsed)
{
ParseFile();
fileParsed = true;
}
if (mainXmpPacket == null)
{
// The file does not contain any XMP data.
return(null);
}
if (mergedXmpPacket == null)
{
if (extendedXmpPacket != null)
{
mergedXmpPacket = XmpUtil.MergeExtendedXmp(mainXmpPacket, extendedXmpPacket);
}
else
{
mergedXmpPacket = mainXmpPacket.Clone();
}
}
return(new JpegXmpPackets(mainXmpPacket, extendedXmpPacket, mergedXmpPacket));
}
private void AssembleExtendedXmpChunks()
{
if (extendedXmpChunks.TryGetValue(extendedXmpGuid, out ExtendedXmp value))
{
if (value.TotalLength > int.MaxValue)
{
ExceptionUtil.ThrowInvalidOperationException("The extended XMP packet is larger than 2GB.");
}
using (MemoryStream memoryStream = new MemoryStream((int)value.TotalLength))
{
IReadOnlyList <ExtendedXmpContent> chunks = value.GetChunks();
uint dstOffset = 0;
foreach (ExtendedXmpContent item in chunks.OrderBy(i => i.Offset))
{
if (item.Length != value.TotalLength)
{
ExceptionUtil.ThrowInvalidOperationException("The extended XMP chunk length does not equal the total packet length.");
}
if (item.Offset == dstOffset)
{
byte[] data = item.GetDataReadOnly();
memoryStream.Write(data, 0, data.Length);
dstOffset += (uint)data.Length;
}
else
{
ExceptionUtil.ThrowInvalidOperationException($"Unexpected offset: { item.Offset }, expected { dstOffset }");
}
}
memoryStream.Position = 0;
extendedXmpPacket = new XmpPacket(memoryStream);
}
}
}
public static XmpPacket MergeExtendedXmp(XmpPacket mainXmp, XmpPacket extendedXmp)
{
if (mainXmp is null)
{
ExceptionUtil.ThrowArgumentNullException(nameof(mainXmp));
}
if (extendedXmp is null)
{
ExceptionUtil.ThrowArgumentNullException(nameof(extendedXmp));
}
XDocument mergedDocument = new XDocument(mainXmp.Document);
XElement mergedRdfElement = mergedDocument.Descendants(RdfContainerElementName).First();
// Remove the xmpNote:HasExtendedXMP element.
XObject hasExtendedXmpObject = FindHasExtendedXmpObject(mergedRdfElement);
if (hasExtendedXmpObject != null)
{
if (ShouldRemoveExtendedXmpParent(hasExtendedXmpObject))
{
hasExtendedXmpObject.Parent.Remove();
}
else
{
MaybeRemoveXmpNoteNamespace(hasExtendedXmpObject.Parent);
if (hasExtendedXmpObject is XAttribute attribute)
{
attribute.Remove();
}
else if (hasExtendedXmpObject is XElement element)
{
element.Remove();
}
}
}
// Add all of the rdf:Description elements in the extended XMP packet to the merged packet.
//
// Section 7.4 of the XMP Specification Part 1 allows a single rdf:RDF element to contain multiple
// rdf:Description elements, with the XMP properties arbitrarily split between them.
//
// The XMP Specification Part 1 can be found at:
// https://wwwimages2.adobe.com/content/dam/acom/en/devnet/xmp/pdfs/XMP%20SDK%20Release%20cc-2016-08/XMPSpecificationPart1.pdf
//
// The relevant portion of section 7.4 is quoted below:
//
// A single XMP packet shall be serialized using a single rdf:RDF XML element.
// The rdf:RDF element content shall consist of only zero or more rdf:Description elements.
//
// The element content of top-level rdf:Description elements shall consist of zero or more XML elements for XMP properties.
// XMP properties may be arbitrarily apportioned among the rdf:Description elements.
XElement extendedXmpRdfElement = extendedXmp.Document.Descendants(RdfContainerElementName).First();
foreach (XElement item in extendedXmpRdfElement.Elements(RdfDescriptionElementName))
{
mergedRdfElement.Add(item);
}
return(new XmpPacket(mergedDocument));
}
private void GatherXmpDataFromFile(EndianBinaryReader reader)
{
ushort marker = reader.ReadUInt16();
// Check the file signature.
if (marker == JpegMarkers.StartOfImage)
{
while (reader.Position < reader.Length)
{
marker = reader.ReadUInt16();
if (marker == 0xFFFF)
{
// Skip the first padding byte and read the marker again.
reader.Position++;
continue;
}
if (marker == JpegMarkers.StartOfScan || marker == JpegMarkers.EndOfImage)
{
// The application data segments always come before these markers.
break;
}
ushort segmentLength = reader.ReadUInt16();
if (segmentLength < 2)
{
ExceptionUtil.ThrowFormatException($"JPEG segment length must be in the range of [2, 65535], actual value: { segmentLength }");
}
// The segment length field includes its own length in the total.
segmentLength -= sizeof(ushort);
if (marker == JpegMarkers.App1)
{
if (mainXmpPacket == null && segmentLength >= MainXmpSignatureLength)
{
string sig = reader.ReadAsciiString(MainXmpSignatureLength);
if (sig.Equals(MainXmpSignature, StringComparison.Ordinal))
{
byte[] xmpPacketBytes = reader.ReadBytes(segmentLength - MainXmpSignatureLength);
mainXmpPacket = new XmpPacket(xmpPacketBytes);
extendedXmpGuid = XmpUtil.GetExtendedXmpGuid(mainXmpPacket);
continue;
}
else
{
reader.Position -= MainXmpSignatureLength;
}
}
if (segmentLength >= ExtendedXmpPrefixLength)
{
string sig = reader.ReadAsciiString(ExtendedXmpSignatureLength);
if (sig.Equals(ExtendedXmpSignature, StringComparison.Ordinal))
{
string guid = reader.ReadAsciiString(ExtendedXmpGUIDLength);
uint length = reader.ReadUInt32();
uint offset = reader.ReadUInt32();
byte[] data = reader.ReadBytes(segmentLength - ExtendedXmpPrefixLength);
if (extendedXmpChunks.TryGetValue(guid, out ExtendedXmp value))
{
value.AddChunk(data, offset, length);
}
else
{
extendedXmpChunks.Add(guid, new ExtendedXmp(data, offset, length));
}
continue;
}
else
{
segmentLength -= ExtendedXmpSignatureLength;
}
}
}
reader.Position += segmentLength;
}
}
}
private XmpPacket(XmpPacket cloneMe)
{
Document = new XDocument(cloneMe.Document);
LengthInBytes = cloneMe.LengthInBytes;
}
