Re: How do I get X, Y pos and PangoLogAttr of each glyph in a rendered string?

[Alex Kerr <alex phonething com>]

Thanks very much for the help.

> You definitely can do it with glyphs...

OK, cool, so how - i.e. which APIs and how do I tie them together 
please? That's what's got me stuck!

> ...but is that really what you want? There's simpler API in pango to 
do that per cluster.

I'm not sure :) What's the definition of a cluster (and for that matter 
a glyph) ? I can't find this in the docs.

And what's the simpler API you're referring to?

Thanks for the Python code. I can't actually use Python (don't program 
in it, don't have it installed) but will read it as pseudocode and 
attempt similar in C!

Cheers
Alex

 On 20/04/2011 06:11, Behdad Esfahbod wrote:
> On 04/19/11 16:27, Alex Kerr wrote:
> > Hello,
> Hi Alex,
>
> > I'm using a really basic Cairo Pango prog as a test bed. It just displays a
> > short string on a Cairo surface using a Pango layout, which works fine.
> >
> > For each glyph in the string, I now want to get it's X,Y pos (and width and
> > height) on the rendered Cairo surface, and the PangoLogAttr data, e.g. so I
> > could draw a box around each glyph, or whatever.
> >
> > After a lot of reading the API stuff, and googling for examples, I'm not quite
> > sure how to tie the API functions together to achieve this. Anyone got any
> > suggestions, ideas, or code please?
> You definitely can do it with glyphs, but is that really what you want?
> There's simpler API in pango to do that per cluster.  Note that you cannot map
> a glyph to the original string (and hence PangoLogAttr).  You can only do that
> per cluster.
>
> Check PangoLayoutIter.
>
> I'm also attaching Python code that draws boxes around clusters.
>
> Hope that helps,
> behdad
>
> > Pseudocode for what I'm trying to do would be:
> >
> > 1. Render Pango text to Cairo surface (note: could be right-to-left, e.g.
> > Arabic, as well as left-to-right) - Done this.
> >
> > 2. For each glyph (or ligature) in the line of text:
> >      {
> >      3. Get X, Y, Width and Height of rendered glyph (or ligature)
> >      4. Get the PangoLogAttr structure for the same character
> >      5. Move onto the next glyph (/ligature/character) in the line
> >      }
> >
> > P.S. As a separate side note, I understand glyphs to be the separate
> > components of a final rendered character, i.e. the main body and diacritic (if
> > present) would be separate glyphs. Each glyph in turn could possibly be made
> > up of more than one UTF-8 character. The rendering engine can potentially
> > combine certain combinations of glyphs to form a single ligature. Glyphs or
> > ligatures can also be referred to as characters (so PangoLogAttr applies to
> > ligatures and glyphs?). Have I got this right!?
> >
> > Any help much appreciated :)
> >
> > Many thanks indeed!
> > Alex
> >
> >
> >
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