[FFmpeg-devel] [PATCH] vf_drawtext: make x and y options parametric

[Stefano Sabatini]

On date Friday 2011-09-23 02:41:26 +0200, Stefano Sabatini encoded:
> On date Thursday 2011-09-22 01:14:12 +0200, Stefano Sabatini encoded:
> > On date Wednesday 2011-09-21 22:14:26 +0200, Víctor Paesa encoded:
> > > Hi,
> [...]
> > > So the example (ruining parametric horizontal centering) is:
> > > drawtext=fontsize=30:fontfile=FreeSerif.ttf:fontcolor=green:text='g':x=w/2:y=(h-text_h+ascent-line_h)/2
> > > drawtext=fontsize=30:fontfile=FreeSerif.ttf:fontcolor=red:text='ood':x=w/2+22:y=(h-text_h+ascent-line_h)/2
> > 
> > Updated work in progress, not still ready for commit with a few fixes
> > and the addition of the ascent/descent/max_glyph_w constants.
> > 
> > Still missing:
> > 
> > * documentation for the new variables (in particular about the meaning
> >   of ascent/descent)
> > 
> > * better names or short aliases for max_glyph_h/w (suggestions are
> >   welcome...), also max_glyph_h == line_h so maybe I should keep an
> >   alias for that
> 
> Nit, now we have:
> "max_glyph_w",   ///< max glyph width
> "max_glyph_h",   ///< max glyph height
> "ascent",        ///< max glyph ascent
> "descent",       ///< max glyph descent
> 
> maybe a better scheme could be:
> max_glyph_w
> max_glyph_h
> max_glyph_a
> max_glyph_d
> 
> Opinions?

Created aliases.

> > * figure out how to deal with the wrapline feature, I don't think it
> >   is possible to conciliate it easily with moving x/y, but I see it is
> >   useful under certain scenarios so I'd like to keep it at least as a
> >   tweakable option.
> 
> I made my mind, and I believe it's better to drop it at all, rather
> than leave it half-implement, drawtext is not supposed to be a word
> processor, and having an half-baked wrapping feature is not going to
> help in that sense, and drawtext is just supposed to be a thin wrapper
> around the libfreetype capabilities, we may add a text processing
> filter as a separate filter (e.g. wrapping imagemagik or even an HTML
> renderer).
> 
> Updated.

Updated again, I'm going to push it in a day or so if I read no
comments.

Possible improvements:

* detect if the provided text contains % parameters, if not there is
  no need to recompute the size/position each time (should improve
  performance when scrolling big files).
-- 
FFmpeg = Forgiving Forgiving Magical Peaceful Exxagerate Gorilla
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