Re: [ft-devel] my Symbian OS glyph caching system

[jaingaurav001]

Graham Asher wrote:
> 
> 
> Some caveats about my glyph caching system: here is most of the text of
> my reply to Srinavasa: 
> 
> <<<<<< 
> You are welcome to look at my cache implementation: it should be
> somewhere in this folder: 
> 
> http://developer.symbian.org/oss/FCL/sf/os/textandloc/file/030b3432fbe0/fontservices/fontstore
>  
> 
> However: 
> 
> 1. I can't provide support. I wrote this over 10 years ago. Since then
> many other people have worked on it and I no longer know exactly how it
> works. 
> 
> 2. As originally designed, the glyph cache was a binary tree that grew
> to a certain maximum size, after which no more entries could be added.
> For reasons of performance in a multi-processing system, glyphs could
> only be added, not deleted, addition of a glyph to a tree being an
> atomic action requiring no mutex. This design restriction may not exist
> any more; I don't know and don't have the time to find out. 
> 
> 3. Therefore you may be better advised, in a single-processing system,
> to create your own LRU glyph caching system. In principle it's simple
> (and I have used a variant of this design for my proprietary CartoType
> map rendering library): create a suitable database structure that
> stores key-value pairs where the key is the unique style of the glyph
> (font family, size, transform, emboldening, etc.) and the value is the
> glyph. Keep track of the least recently used glyph using a linked list;
> or simply rely on hashing, and remove glyphs where a conflict occurs. 
> >>>>>> 
> 
> Best regards, 
> 
> Graham Asher 
> 
> Hi Graham,
> 
> Could you please point from where in the mentioned link i can get a your
> caching code which you have developed for the symbian.
> 
> http://developer.symbian.org/oss/FCL/sf/os/textandloc/file/030b3432fbe0/fontservices/fontstore
> 
> Regards,
> Gaurav
> 
> 
> Werner LEMBERG wrote:
> 
>   
>     We are trying to achieve performance improvement either through
> parallelization/optimization in the freetype-2.3.11 library.  Any
> help in this regard is highly appreciated.
>     
>   
>   
> The solution is caching everything!  Due to the nature of fonts I
> don't see much gain in parallelization while processing a single font.
> 
> Graham Asher mentioned in a previous post that his FreeType caching
> stuff from the symbian OS is now open-source, so you might use this as
> a starting point.
> 
>   http://lists.gnu.org/archive/html/freetype-devel/2010-02/msg00033.html 
> 
> If you can optimize FreeType further (for example, using a profiler to
> isolate hot spots, then rewriting the code to make it faster) this is
> very welcomed.
> 
> 
>     Werner
> 
> 
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