Re: FW: [ft] cache manager

[David Turner]

Hello,

As Werner said, I was in vacation, I'll try to answer your questions here:

Kristján V. Jónsson a écrit :
> Hi there.
> I am reposting this to the list since I got not a single response.  Maybe 
> something went wrong.  These are issues of some importance.
> 1) is important in our application since the node ID is actually a strong 
> reference to an application object that needs to be released when the CM 
> doesn't know about it any more.
> 2) is perhaps more important.  The CM is only truly useful if one can hook into 
> its loading and transformation stage to provide custom slanting and embolding 
> and perhaps other effects.  Somewhere in the archives someone mentioned 
> subclassing in this context.  Any more infor on that?
>
>   
You're essentially asking for the ability to define custom nodes within 
the cache, and this is something that did exist
in previous releases of FreeType, but was explicitely removed for 2.2.1 
for several reasons:

- first of all, nobody seemed to use this "feature"

- second, I wanted to be able to change some internals in order to improve
 certain aspects of the implementation, without breaking clients.

Before 2.2.1, it was possible to write a "custom cache" used to store 
custom nodes which could be *anything*,
including custom glyph images. However, the level of details to master 
to do that was very high (unfortunately,
writing a cache that is efficient, flexible and deals well with 
out-of-memory conditions isn't trivial), and I guess that's
why nobody really tried to.

My goal is now to provide a much simpler API that allows users to store 
custom glyph bitmaps and outlines in the
cache, and nothing more. However, this is not on my priority list, and I 
don't even promise I'll implement this in 2006,
nor that it will allow the user to know when a cache node is flushed.

So, I invite you to either write your own cache, or grab a copy of the 
one available in 2.1.10 and modify it to suit
your needs. This would become part of your application, and by simply 
renaming its types and functions, it would
happily live side-by-side with any FreeType release.

Hope this helps,

- David Turner
- The FreeType Project  (www.freetype.org)







> K 
>
> -----Original Message-----
> From: address@hidden [mailto:address@hidden On Behalf Of Kristján V. Jónsson
> Sent: 3. júlí 2006 14:17
> To: address@hidden
> Subject: [ft] cache manager
>
>  
> Hello there.
> I am new to this list although I have been using freetype for a while now.
> So, please excuse me if this has been covered before.
>
> I use the cache manager interface to freetype for convenience.  However, there 
> are two things there which I find sorely missing:
>
> 1) I need CM to tell me when a node goes out of cache.
> 2) I need to be able to hook into the glyph rendering process so that I can 
> provide gransformations for the glyph before caching.  This is to allow me to 
> embolden and slant the glyph, for example.
>
> Is there a way to do this?  Or is it simple to enhance freetype to support this?
>
> Cheers,
>
> Kristjan
>
>
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>   


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