Undocumented in source.
A PangoGlyphItemIter is an iterator over the clusters in a PangoGlyphItem The <firstterm>forward direction</firstterm> of the iterator is the logical direction of text. That is, with increasing start_index and start_char values. If glyph_item is right-to-left (that is, if <literal>glyph_item->item->analysis.level</literal> is odd), then start_glyph decreases as the iterator moves forward. Moreover, in right-to-left cases, start_glyph is greater than end_glyph.