[Fontconfig] Tutorial or guidance for using fontconfig

[Jesper L. Nielsen]

> Jesper L. Nielsen wrote:
>
>> I do have a various number of fonts for different languages and other
>> things, so the first performance hit is when fontconfig builds it's
>> cache on startup, if there is a way to disable this, I haven't  
>> found it.
>
> Sure, building caches is slow.  The first question is why is it  
> building the
> cache on each startup.
>

Because it is on an embedded system and no place to save the caching  
database after each reboot. However I can work past that using some  
NFS trickery.

>> I have been running sysprof and the majority of time spend while
>> rendering fonts seems to be in fontconfig.
>>
>> I don't know how to dump Sysprof output to text, so I've attached a
>> screendump.
>
> The screenshot shows nothing really.  The fontconfig functions you  
> are showing
> in the shot are taking only 3% of the total time.
>

True, I'll get some better numbers on the embedded system soon. But  
the screenshot only shows a simple test program I produced to profile  
the pango calls. So the times should be regarded as relativ, and  
kernel time used disregarded.
>> So what I mean is that there a references to FcPattern, PangoFcFont  
>> and
>> other things defined in the Fontconfig specific source files. So  
>> taking
>> out just the Fontconfig part for the pangoft2.c would require some  
>> work.
>
> pantoft2 subclasses pangofc.  So, you are pretty much talking about  
> writing a
> new pango backend.  And then, the pango shapers also depend on  
> pangofc.  So
> you have to modify those too.  Really, your fighting the wrong  
> battle.  Just
> focus on getting fontconfig working for you.
>
I was mustering myself to write a whole new backend, but if the shaper  
also uses FontConfig, I think I'll better give FontConfig another shot.

Jesper