PS/PDF rendering problems (was Re: Dia ChangeLog report for 2009-03-27 04:00:00 UTC (Fri 27 Mar))

[Hans Breuer <hans breuer org>]

At 27.03.2009 12:51, Lars Ræder Clausen wrote:
> On Fri, 2009-03-27 at 12:32 +0100, Hans Breuer wrote:
> > At 27.03.2009 12:06, Lars RÊder Clausen wrote:
> > > On Fri, 2009-03-27 at 05:13 +0100, Dia ChangeLog Daemon wrote:
> > > > Snapshots available at http://www.raeder.dk/~larsrc/Dia/snapshots
> > > >
> > > > *** Recent ChangeLog entries:
> > > >
> > > > --- ChangeLog.previous  2009-03-26 05:00:12.000000000 +0100
> > > > +++ dia-svn-snapshot/ChangeLog  2009-03-27 05:00:09.529464448 +0100
> > > > @@ -1,3 +1,10 @@
> > > > +2009-03-25  Hans Breuer  <hans breuer org>
> > > > +
> > > > +       * plug-ins/diapsrenderer.c : dont't throw away alignment information
> > > > +       an don't scale text arbitrary, we can't predict the Latin-1 font size
> > > > +       exactly enough. Fiyes bug #575186.
> > > Just did some sample diagrams on 0.97-pre2 and the newest SVN, and they
> > > both have severe problems with text in the PS export, as can be seen
> > > with this conversion of render-test.dia. This is a regression since
> > > 0.96.1.
> > What's the problem in the PDF you are refering to? Maybe the overlapping 
> > glyphs as in: http://bugzilla.gnome.org/show_bug.cgi?id=573261
> >
> >  From my understanding this is not a regression between 0.96 and 0.97 but 
> > simply some earlier unnoticed bad side-effect of Pango's font hinting.
> > It should go away if you use a font without kerning information.
>
> Yes, looks like that. However, render-test looks nice when coming from
> 0.96.1 on the very same setup. So either something in the rendering code
> changed, or the way Dia picks the actual font has changed. I seem to
> remember forcing Pango to not use hinting, did that fall by the wayside?
I'm still confused. If you are referring to 
plug-ins/postscript/diapsrenderer.c there is not (and was not in 0.96) any 
font hinting involved. But than your PDF must have been created with some 
other tool than Dia.

If the PDF is coming from Dia the only current way (I know) is using the 
diacairo plug-in. But that never included any explicit font hinting code 
either. It got converted to use Pangocairo since 0.96, though:

2007-10-12  Hans Breuer  <hans breuer org>

        * plug-ins/cairo/diacairo.c plug-ins/cairo/diacairo-interactive.c :
        use PangoCairo when available (HAVE_PANGOCAIRO_H)


I tried mysef to switch off some hinting in Pango, but originally failed 
with that. IIRC finally there was a comment in Pango about some missing 
implementation.

But yesterday I seem to have found a fix for bug #573261.

So everything should be fine now :-)

        Hans

-------- Hans "at" Breuer "dot" Org -----------
Tell me what you need, and I'll tell you how to
get along without it.                -- Dilbert