Re: [ft] Multiple FreeType2 versions in an application

[Mickey Gabel]

We have a similar potential issue with statically linked ft2, and maybe 
people on the list have an idea.

We have a text rendering library for embedded platforms, built using a 
custom build of FT2, statically linked into the client application.
To be more specific, our library XX.lib includes our own object files as 
well as the object files from the custom build of FT2. That way the 
client app doesn't have to link against two libraries, and also we can 
be sure that the necessary custom build of FT2 is used.

However, we worry about clients that want to use FT2 themselves directly 
(for example, they want to get some info from a font file, which we 
don't provide). Such a client would also link against some other version 
of FT2 that is not our custom build. This will cause link errors due to 
multiple identical symbols.

I originally thought of doing the same as Ineiev (replacing "FT_*" with 
"internalFT_*").
Does anyone have any better ideas?
Will asking the client to link against a dynamically loaded version of 
FT2 magically solve this issue for such client?

Mickey


Ineiev wrote:
> Sorry, forwarding to the list
> ---------- Forwarded message ----------
> From: Ineiev <address@hidden>
> Date: Mar 31, 2009 10:28 AM
> Subject: Re: [ft] Multiple FreeType2 versions in an application
> To: Werner LEMBERG <address@hidden>
>
>
> On 3/30/09, Werner LEMBERG <address@hidden> wrote:
>  >> First of all, though I can build and run it on my systems, won't the
>  >> libraries conflict on another system?
>  >
>  > If you link statically, this can't happen.
>
>
> How nice!
>
>
>  >> Then, will it really provide repeatability with accuracy of an LSB
>  >> or so?
>  >
>  > What's `LSB'?  In addition, I don't understand the question.  Please
>  > elaborate.
>
>
> I meant least significant bit - possible round-off and other small
>  computation errors; probably a stupid question, but I am quite new to
>  the library.
>
>
>  >> At last, is there any way to use more than one FreeType2 version in
>  >> the application? say, if I eventually want to upgrade the internally
>  >> used library, I'll need to provide compatibility with files created
>  >> with older versions of the tool.
>  >
>  > In theory, this is possible, I believe, if you use DLL versions of the
>  > FreeType library, and you enforce linking to a certain version.
>  > Another solution (at least with GNU/Linux) is to preload the library
>  > using the LD_PRELOAD environment variable to load a specific versions.
>  > Note, however, that those my observations are educated guesses only.
>
>
> Thank you. I'll try.
>
>
>  > It's not clear to me why you want to upgrade the FreeType library at
>  > all if you want to assure a certain rasterization...
>
>
> Certainly, there is a contradiction. I must leave old texts as they were,
>  but it is not impossible that I'll want features of a newer version
>  (for new texts); of course, it is not very likely to happen because
>  the library is very stable now.
>
>  Best regards,
>
>    Ineiev
>
>
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