Re: How to extract rendered glyphs (graphemes?) with Pango?

[Alex Kerr <alex phonething com>]

OK, thanks very much for that. I've looked at those structures and I'm 
still not clear how to pull the combined, shaped and rendered glyphs out 
in bitmap form though. Those structures appear to hold geometry and 
other data, but not in rendered form. i.e. I actually need to 
programmatically cut up the rendered glyphs out of the rendered bitmap 
string. or alternatively pass the data for individual graphemes (glyphs? 
whatever the final product is of combining multiple unicode code points 
and then shaping them etc) to the renderer one at a time. I will say, 
this process does not have to be efficient at all as it won't be used in 
real time, just to render and then chop up (visually) the generated letters.

So:

a.) How do I get at the rendered letters (in visual order) ?
b.) How do I separate out the diacritics also in rendered form (if at 
all possible) and know where to place them (in pixels) relative to the 
main character?
c.) How do I uniquely identify each rendered letter so that I know if I 
encounter it a second time in the text I'm processing.

I'm guessing I do a normal render of the text using pangocairo (e.g. as 
per examples I've found), then somehow chop the bitmap up (or copy from 
it) according to position data held in the structures somewhere - but 
not sure of specifics! Any specifics much appreciated :)

Many thanks,
Alex

On 14/03/2011 20:56, Behdad Esfahbod wrote:
> On 03/14/11 15:38, Alex Kerr wrote:
> > Also, I don't suppose it's possible to extract rendered diacritics is it, and
> > positioning information for them relative to the base character they're
> > attached to? Would be amazing if so :)
> That's essentially what PangoGlyphString does.  Combined with the text itself,
> ie, PangoGlyphItem, it gives you full information about the clusters.  Check
> PangoGlyphItemIter for example, which iterates clusters withing a PangoGlyphItem.
>
> > From a PangoLayout you can get to the GlyphItems simply by getting the lines
> out of the layout and traversing line->runs which is a list of
> PangoLayoutRun's.  PangoLayoutRun being a typedef to PangoGlyphItem.
>
> Cheers,
> behdad