If
#next() return
#EVENT_NEW_TAG or
#EVENT_VALUE_OF_REGISTERED_TAG, call this function to get the
corresponding tag.
For
#EVENT_NEW_TAG, the tag may not contain the value if the size
of the value is greater than 4 bytes. One should call
ExifTag#hasValue() to check if the tag contains value. If there
is no value,call
#registerForTagValue(ExifTag) to have the parser
emit
#EVENT_VALUE_OF_REGISTERED_TAG when it reaches the area
pointed by the offset.
When
#EVENT_VALUE_OF_REGISTERED_TAG is emitted, the value of the
tag will have already been read except for tags of undefined type. For
tags of undefined type, call one of the read methods to get the value.