public IFDEntry(EndianBinaryReader reader)
{
Tag = reader.ReadUInt16();
Type = (ExifValueType)reader.ReadInt16();
Count = reader.ReadUInt32();
Offset = reader.ReadUInt32();
}
/// <summary>
/// Parses the EXIF data into a collection of properties.
/// </summary>
/// <param name="exifBytes">The EXIF bytes.</param>
/// <returns>
/// A collection containing the EXIF properties.
/// </returns>
/// <exception cref="ArgumentNullException"><paramref name="exifBytes"/> is null.</exception>
internal static ExifValueCollection Parse(byte[] exifBytes)
{
if (exifBytes == null)
{
throw new ArgumentNullException(nameof(exifBytes));
}
List <MetadataEntry> metadataEntries = new List <MetadataEntry>();
MemoryStream stream = null;
try
{
stream = new MemoryStream(exifBytes);
Endianess?byteOrder = TryDetectTiffByteOrder(stream);
if (byteOrder.HasValue)
{
using (EndianBinaryReader reader = new EndianBinaryReader(stream, byteOrder.Value))
{
stream = null;
ushort signature = reader.ReadUInt16();
if (signature == TiffConstants.Signature)
{
uint ifdOffset = reader.ReadUInt32();
List <ParserIFDEntry> entries = ParseDirectories(reader, ifdOffset);
metadataEntries.AddRange(ConvertIFDEntriesToMetadataEntries(reader, entries));
}
}
}
}
catch (EndOfStreamException)
{
}
finally
{
stream?.Dispose();
}
return(new ExifValueCollection(metadataEntries));
}
private static List <ParserIFDEntry> ParseDirectories(EndianBinaryReader reader, uint firstIFDOffset)
{
List <ParserIFDEntry> items = new List <ParserIFDEntry>();
bool foundExif = false;
bool foundGps = false;
bool foundInterop = false;
Queue <MetadataOffset> ifdOffsets = new Queue <MetadataOffset>();
ifdOffsets.Enqueue(new MetadataOffset(MetadataSection.Image, firstIFDOffset));
while (ifdOffsets.Count > 0)
{
MetadataOffset metadataOffset = ifdOffsets.Dequeue();
MetadataSection section = metadataOffset.Section;
uint offset = metadataOffset.Offset;
if (offset >= reader.Length)
{
continue;
}
reader.Position = offset;
ushort count = reader.ReadUInt16();
if (count == 0)
{
continue;
}
items.Capacity += count;
for (int i = 0; i < count; i++)
{
ParserIFDEntry entry = new ParserIFDEntry(reader, section);
switch (entry.Tag)
{
case TiffConstants.Tags.ExifIFD:
if (!foundExif)
{
foundExif = true;
ifdOffsets.Enqueue(new MetadataOffset(MetadataSection.Exif, entry.Offset));
}
break;
case TiffConstants.Tags.GpsIFD:
if (!foundGps)
{
foundGps = true;
ifdOffsets.Enqueue(new MetadataOffset(MetadataSection.Gps, entry.Offset));
}
break;
case TiffConstants.Tags.InteropIFD:
if (!foundInterop)
{
foundInterop = true;
ifdOffsets.Enqueue(new MetadataOffset(MetadataSection.Interop, entry.Offset));
}
break;
case TiffConstants.Tags.StripOffsets:
case TiffConstants.Tags.RowsPerStrip:
case TiffConstants.Tags.StripByteCounts:
case TiffConstants.Tags.SubIFDs:
case TiffConstants.Tags.ThumbnailOffset:
case TiffConstants.Tags.ThumbnailLength:
// Skip the thumbnail and/or preview images.
// The StripOffsets and StripByteCounts tags are used to store a preview image in some formats.
// The SubIFDs tag is used to store thumbnails in TIFF and for storing other data in some camera formats.
//
// Note that some cameras will also store a thumbnail as part of their private data in the EXIF MakerNote tag.
// The EXIF MakerNote tag is treated as an opaque blob, so those thumbnails will be preserved.
break;
default:
items.Add(entry);
break;
}
System.Diagnostics.Debug.WriteLine(entry.ToString());
}
}
return(items);
}
