private static void ProcessTag(SequentialReader reader, Directory directory, int directoryType, int tagType, int tagByteCount)
{
var tagIdentifier = tagType | (directoryType << 8);
// Some images have been seen that specify a zero byte tag, which cannot be of much use.
// We elect here to completely ignore the tag. The IPTC specification doesn't mention
// anything about the interpretation of this situation.
// https://raw.githubusercontent.com/wiki/drewnoakes/metadata-extractor/docs/IPTC-IIMV4.2.pdf
if (tagByteCount == 0)
{
directory.Set(tagIdentifier, string.Empty);
return;
}
switch (tagIdentifier)
{
case IptcDirectory.TagCodedCharacterSet:
{
var bytes = reader.GetBytes(tagByteCount);
var charset = Iso2022Converter.ConvertEscapeSequenceToEncodingName(bytes);
if (charset == null)
{
// Unable to determine the charset, so fall through and treat tag as a regular string
charset = Encoding.UTF8.GetString(bytes, 0, bytes.Length);
}
directory.Set(tagIdentifier, charset);
return;
}
case IptcDirectory.TagEnvelopeRecordVersion:
case IptcDirectory.TagApplicationRecordVersion:
case IptcDirectory.TagFileVersion:
case IptcDirectory.TagArmVersion:
case IptcDirectory.TagProgramVersion:
{
// short
if (tagByteCount == 2)
{
var shortValue = reader.GetUInt16();
reader.Skip(tagByteCount - 2);
directory.Set(tagIdentifier, shortValue);
return;
}
break;
}
case IptcDirectory.TagUrgency:
{
// byte
directory.Set(tagIdentifier, reader.GetByte());
reader.Skip(tagByteCount - 1);
return;
}
}
// If we haven't returned yet, treat it as a string
// NOTE that there's a chance we've already loaded the value as a string above, but failed to parse the value
var encodingName = directory.GetString(IptcDirectory.TagCodedCharacterSet);
Encoding?encoding = null;
if (encodingName != null)
{
try
{
encoding = Encoding.GetEncoding(encodingName);
}
catch (ArgumentException)
{ }
}
StringValue str;
if (encoding != null)
{
str = reader.GetStringValue(tagByteCount, encoding);
}
else
{
var bytes = reader.GetBytes(tagByteCount);
encoding = Iso2022Converter.GuessEncoding(bytes);
str = new StringValue(bytes, encoding);
}
if (directory.ContainsTag(tagIdentifier))
{
// this fancy string[] business avoids using an ArrayList for performance reasons
var oldStrings = directory.GetStringValueArray(tagIdentifier);
StringValue[] newStrings;
if (oldStrings == null)
{
// TODO hitting this block means any prior value(s) are discarded
newStrings = new StringValue[1];
}
else
{
newStrings = new StringValue[oldStrings.Length + 1];
Array.Copy(oldStrings, 0, newStrings, 0, oldStrings.Length);
}
newStrings[newStrings.Length - 1] = str;
directory.Set(tagIdentifier, newStrings);
}
else
{
directory.Set(tagIdentifier, str);
}
}
private static void ProcessTag([NotNull] SequentialReader reader, [NotNull] Directory directory, int directoryType, int tagType, int tagByteCount)
{
var tagIdentifier = tagType | (directoryType << 8);
// Some images have been seen that specify a zero byte tag, which cannot be of much use.
// We elect here to completely ignore the tag. The IPTC specification doesn't mention
// anything about the interpretation of this situation.
// https://raw.githubusercontent.com/wiki/drewnoakes/metadata-extractor/docs/IPTC-IIMV4.2.pdf
if (tagByteCount == 0)
{
directory.Set(tagIdentifier, string.Empty);
return;
}
string str = null;
switch (tagIdentifier)
{
case IptcDirectory.TagCodedCharacterSet:
{
var bytes = reader.GetBytes(tagByteCount);
var charset = Iso2022Converter.ConvertEscapeSequenceToEncodingName(bytes);
if (charset == null)
{
// Unable to determine the charset, so fall through and treat tag as a regular string
str = Encoding.UTF8.GetString(bytes);
break;
}
directory.Set(tagIdentifier, charset);
return;
}
case IptcDirectory.TagEnvelopeRecordVersion:
case IptcDirectory.TagApplicationRecordVersion:
case IptcDirectory.TagFileVersion:
case IptcDirectory.TagArmVersion:
case IptcDirectory.TagProgramVersion:
{
// short
if (tagByteCount >= 2)
{
var shortValue = reader.GetUInt16();
reader.Skip(tagByteCount - 2);
directory.Set(tagIdentifier, shortValue);
return;
}
break;
}
case IptcDirectory.TagUrgency:
{
// byte
directory.Set(tagIdentifier, reader.GetByte());
reader.Skip(tagByteCount - 1);
return;
}
case IptcDirectory.TagReleaseDate:
case IptcDirectory.TagDateCreated:
case IptcDirectory.TagDigitalDateCreated:
{
// Date object
if (tagByteCount >= 8)
{
str = reader.GetString(tagByteCount);
Debug.Assert(str.Length >= 8);
int year, month, day;
if (int.TryParse(str.Substring(0, 4), out year) &&
int.TryParse(str.Substring(4, 2), out month) &&
int.TryParse(str.Substring(6, 2), out day) &&
DateUtil.IsValidDate(year, month, day))
{
directory.Set(tagIdentifier, new DateTime(year, month, day, 0, 0, 0, DateTimeKind.Unspecified));
return;
}
}
else
{
// fall through and we'll process the 'string' value below
reader.Skip(tagByteCount);
}
break;
}
}
// If we haven't returned yet, treat it as a string
// NOTE that there's a chance we've already loaded the value as a string above, but failed to parse the value
if (str == null)
{
var encodingName = directory.GetString(IptcDirectory.TagCodedCharacterSet);
Encoding encoding = null;
if (encodingName != null)
{
try
{
encoding = Encoding.GetEncoding(encodingName);
}
catch { }
}
var bytes = reader.GetBytes(tagByteCount);
if (encoding == null)
{
encoding = Iso2022Converter.GuessEncoding(bytes);
}
if (encoding == null)
{
encoding = Encoding.UTF8;
}
str = encoding.GetString(bytes);
}
if (directory.ContainsTag(tagIdentifier))
{
// this fancy string[] business avoids using an ArrayList for performance reasons
var oldStrings = directory.GetStringArray(tagIdentifier);
string[] newStrings;
if (oldStrings == null)
{
// TODO hitting this block means any prior value(s) are discarded
newStrings = new string[1];
}
else
{
newStrings = new string[oldStrings.Length + 1];
Array.Copy(oldStrings, 0, newStrings, 0, oldStrings.Length);
}
newStrings[newStrings.Length - 1] = str;
directory.Set(tagIdentifier, newStrings);
}
else
{
directory.Set(tagIdentifier, str);
}
}
