the text to itemize.
the number of bytes (not characters) to process, or -1 if @text is nul-terminated and the length should be calculated.
input base direction, and output resolved direction.
Return: a newly allocated array of embedding levels, one item per character (not byte), that should be freed using g_free.
1.4
This will return the bidirectional embedding levels of the input paragraph as defined by the Unicode Bidirectional Algorithm available at:
http://www.unicode.org/reports/tr9/
If the input base direction is a weak direction, the direction of the characters in the text will determine the final resolved direction.