Re: pango_layout_iter_get_char_extents()

[Havoc Pennington <hp redhat com>]

Sven Neumann <sven gimp org> writes: 
> The fact that empty clusters are added at the end of the line is 
> documented and did not surprise me, but clusters are definitely
> not handled as described in your first reply (you said they'd be
> equivalent to a font glyph). The iterator and get_extents function
> behave as if clusters were lines (at least for the case of simple
> layouts without attribute changes).

Clusters are equivalent to a font glyph, but perhaps abused a bit in
the iterator API. 
 
> > IIRC cluster-splitting cases may happen from time to time, if
> > graphemes and clusters are not identical for some reason.
> > 
> > That is, some languages may allow you to do the equivalent of
> > selecting the accent but not the letter the accent is over the top of.
> 
> yes probably, but the extents returned from 
> pango_layout_iter_get_char_extents won't help you to visually select
> (highlight or whatever) the accent since they are simply bogus values
> if calculated by cluster_width / char_count. They do not even give you
> to the correct extents of simple, uncombined glyphs. Better gid rid of 
> this unused and unusable API functions before more people get confused.
> 

Owen's example of the fi ligature is a better explanation of why this
is needed. You want to draw the selection midway through the fi glyph.

Havoc