Re: [Silgraphite-devel] Re: Pango and SILGraphite was Re: Possible Pango 1.4 ideas

[ytang0648 aol com]

In a message dated 1/30/2003 10:22:46 AM Eastern Standard Time, otaylor redhat com writes:

> 
> > One question. How does pango decide which shaper to use ? What is
> > the algorithm (based on PangoCoverage ?) to dertermine which shaper
> > to be used?
> 
> The current algorithm is that modules are registered by:
> 
>  Backend (Xft fonts, old style X fonts, win32 fonts, etc.)
>  Covered ranges
> 
> And for a given backend, Pango always picks the same shaper for the 
> same range.
> 
> This system would clearly need to be extended a bit if we 
> had
> different shapers for different subtypes of fonts (OpenType,
> Graphite) fonts within the same Xft backend.
> 
> Regards,
>                                         Owen

hum... so the OT xft font currently is not a subclass of xft font backend ?
Are you saying that in 1.1.6 you will use the same shaper to deal with a Thai OpenType font and a Thai TrueType font ? ( I know the OpenType Thai is not supported, but in case you do, is that will be the case?)

I guess backend take higher priority than the coverage, right ?
Since Graphite will be able to handle all unicode range without particular algorithm for a particular coverage, the better way to trigger (switch to) it's shapper is to check the availability of one uniq table ('Sil '). and if that table is available, use the Graphite Shaper for all the Unicode conde point that you can find in the 'cmap'. 


I am not that clear about the PangoCoverage in the shaper code. Does that refer to the coverage of the hard wire logic? or does that refer to the coverage of a particular TrueType font? I guess in the case of the shaper api, it refer to the hard wire logic, right?

Do you use the same PangoCoverage data type in other places refer to the Unicode code point coverage of a particular font ?
Where ?

Thanks for your help. 1.1.6 is the version I should look into, right?