Re: [Devel] use of zlib

[David Turner]

Jacob (=Jouk) Jansen wrote:
> Hi All,
>
> in src/gzip/ftgzip.c it is stated :
> #  if 1  /* we choose to include directly the zlib sources in this component */
>          /* this is done to avoid ugly library dependencies                  */
>
>
> This statement is rather taste/system dependend. The solution chosen here
> is quite ugly for OpenVMS: when you try to use the freetype2 library in one
> program together with code where the original zlib is required one get a lot
> of warnings about externals which are multiple defined in the libraries.
> Ofcourse one can solve it by "prefix" all the zlib routines in ft's zlib.
> However : -the list in zconf.h is not complete and has to maintained every
>             time zlib is upgraded.
>           -the executables become larger since much code is included twice,
>             without any gain in performance.
>         

I know it's not optimal, but external library dependencies are a nightmare to
support on multiple platforms; I also really despise Autoconf and don't want
to touch a single line of this atrocity. That's why I did ask in this list
for a volunteer to deal with this issue before committing the changes :o)

Let me propose you a sort of "deal":

  A - I modify FreeType in order to:

     * move the zlib sources from "src/gzip" to another
       place, like "extras/zlib" for example.

     * provide a new configuration macro, like
       FT_CONFIG_OPTION_SYSTEM_ZLIB (defined in "ftoption.h")

     * modify "src/gzip/ftgzip.c" and/or the build system
       to include the files in "extras/zlib" *OR* to use
       the system zlib when the configuration macro is
       defined.

  B - someone (that means you, or someone else), provides patches
      to perform the latter:

        - modify builds/unix/configure.in to allow it to accept a
          new option, like "--with-system-zlib", with relevant
          actions on the build system.

        - provide a similar option for VMS builds (that use
          the "descrip.mms" files).

        - modify "freetype-config" so that it returns the correct
          library dependencies on Unix

      I will make the changes to the Jamfiles myself.

I propose to define a build variable named "FT2_SYSTEM_ZLIB"
(in Makefile/Jamfile/descrip.mms). When defined, it should contain
the include path to the zlib header files. When not defined, the
"extras/zlib" sources should be used instead.

If you do part B, I'll do part A. What do you think about that ?

Regards,

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