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Re: [Freetype] (no subject)

From: David Turner
Subject: Re: [Freetype] (no subject)
Date: Wed, 22 Nov 2000 20:01:39 +0100

Hi George,

>     Hi all,
> Is there anybody who can give me an advice?
> I have encoutered the following problem :
>     freetype is too slow for direct rendering of each char in the text,
> without any chaching.

Yes, that's "by design" I might add, and there's nothing wrong about it

>     I think that 300-1500 char/sec. (depending on size and font compexity)
> on Pentium III 500 is extremly slow. I really need 2-3 grades higher
> performance becouse my text rendering isn't the only proccess on CPU, but if
> even it is, I can see screen blinking within render/blitting operation.
> 1 or 2 seconds  rendering time of one screen full of 1500-2000 chars is
> pretty much for me : ).
> I can spend 10~15Mb for  glyph->bitmap cache for gaining 20-30 times faster
> text layouting. Is this a dream? I think that itsn't :). Don't ask me why I
> don't  render all needed fonts and sizes in advance, if and I want to have a
> so fast engine :).

there is a beta caching sub-system provided with FreeType 2.0. It is
already used by "ftview" actually. For more information, you should look
at <freetype/ftcache.h> and the content of <freetype/cache/..>, as well
as see the source code in "ft2demos/src/ftcommon.i".

A draft design documentation for the caching sub-system can also be
found at, but I admit it isn't
completed, which is the main reason why it hasn't been publicly

the cache system was designed with flexibility in mind, which means
you should be able to use it directly in your application without
it. It is far from being fully optimized for now, but already provides a
_very_ noticeable speed up in rendering speed.

By the way, the default cache size is 200 Kb. This is intentionally low
for testing purposes, but that's enough to cache a lot of glyphs when
using the FTC_SBit_Cache (the FTC_Image_Cache is more greedy but is
suitable for outline glyph images).. You might want to raise this
by a few hundred Kbs (10~15Mb is certainly too much :-)

And I'd be happy to know how many pages per second you'll be able to
display by using it ;-)


- David

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