private ExifValue CreateValue()
{
if (!_reader.CanRead(12))
{
return(null);
}
ExifTag tag = (ExifTag)ReadShort();
ExifDataType dataType = EnumHelper.Parse(ReadShort(), ExifDataType.Unknown);
object value = null;
if (dataType == ExifDataType.Unknown)
{
return(new ExifValue(tag, dataType, value, false));
}
uint numberOfComponents = ReadLong();
if (dataType == ExifDataType.Undefined && numberOfComponents == 0)
{
numberOfComponents = 4;
}
uint oldIndex = _reader.Index;
uint length = numberOfComponents * ExifValue.GetSize(dataType);
if (length <= 4)
{
value = ConvertValue(dataType, length, numberOfComponents);
}
else
{
uint newIndex = _startIndex + ReadLong();
if (_reader.Seek(newIndex))
{
if (_reader.CanRead(length))
{
value = ConvertValue(dataType, length, numberOfComponents);
}
}
if (value == null)
{
_invalidTags.Add(tag);
_reader.Seek(oldIndex + 4);
return(null);
}
}
_reader.Seek(oldIndex + 4);
bool isArray = value != null && numberOfComponents != 1;
return(new ExifValue(tag, dataType, value, isArray));
}
private IExifValue CreateValue()
{
if (!_reader.CanRead(12))
{
return(null);
}
var tag = (ExifTag)ReadShort();
var dataType = EnumHelper.Parse(ReadShort(), ExifDataType.Unknown);
IExifValue value = null;
if (dataType == ExifDataType.Unknown)
{
return(null);
}
var numberOfComponents = ReadLong();
if (dataType == ExifDataType.Undefined && numberOfComponents == 0)
{
numberOfComponents = 4;
}
var oldIndex = _reader.Index;
var length = numberOfComponents * ExifDataTypes.GetSize(dataType);
if (length <= 4)
{
value = CreateValue(tag, dataType, numberOfComponents);
}
else
{
var newIndex = _startIndex + ReadLong();
if (_reader.Seek(newIndex))
{
if (_reader.CanRead(length))
{
value = CreateValue(tag, dataType, numberOfComponents);
}
}
if (value == null)
{
_invalidTags.Add(tag);
}
}
_reader.Seek(oldIndex + 4);
return(value);
}