Due to  our use of  `libtool' to generate  and install the  FreeType 2
libraries on Unix  systems, as well as other historical  events, it is
generally very difficult  to know precisely which release  of the font
engine is installed on a given system.

This file tries to explain why and to document ways to properly detect
FreeType on Unix.


1. Version and Release numbers
------------------------------

For each new public release of FreeType 2, there are generally *three*
distinct `version' numbers to consider:

  * The official FreeType 2 release number, like 2.7.0 or 2.10.2.

  * The  libtool (and  Unix)  specific version  number, like  23.2.17.
    This is what

      pkg-config freetype2 --modversion

    or

      freetype-config --version

    returns.

  * The platform-specific shared object  number, used for example when
    the library is installed as `/usr/lib/libfreetype.so.6.17.2'.

The platform-specific number is, unsurprisingly, platform-specific and
varies with  the operating system  you are using (several  variants of
Linux, FreeBSD, Solaris, etc.).  You  should thus _never_ use it, even
for simple tests.

The libtool-specific number  does not equal the release  number but is
tied to it.

The  release  number  is  available  at  *compile*  time  through  the
following macros defined in `freetype.h':

  - FREETYPE_MAJOR: major release number
  - FREETYPE_MINOR: minor release number
  - FREETYPE_PATCH: patch release number

See below for a small autoconf fragment.

The  release  number  is  also  available  at  *runtime*  through  the
`FT_Library_Version' API.


2. History
----------

The  following  table  gives,  for   all  releases  since  2.5.0,  the
corresponding  libtool number,  as well  as the  shared object  number
found on _most_ systems, but not all of them:


    release     libtool     so
  -------------------------------
     2.11.1     24.1.18   6.18.1
     2.11.0     24.0.18   6.18.0
     2.10.4     23.4.17   6.17.4
     2.10.3     23.3.17   6.17.3
     2.10.2     23.2.17   6.17.2
     2.10.1     23.1.17   6.17.1
     2.10.0     23.0.17   6.17.0
     2.9.1      22.1.16   6.16.1
     2.9.0      22.0.16   6.16.0
     2.8.1      21.0.15   6.15.0
     2.8.0      20.0.14   6.14.0
     2.7.1      19.0.13   6.13.0
     2.7.0      18.6.12   6.12.6
     2.6.5      18.5.12   6.12.5
     2.6.4      18.4.12   6.12.4
     2.6.3      18.3.12   6.12.3
     2.6.2      18.2.12   6.12.2
     2.6.1      18.1.12   6.12.1
     2.6.0      18.0.12   6.12.0
     2.5.5      17.4.11   6.11.4
     2.5.4      17.3.11   6.11.3
     2.5.3      17.2.11   6.11.2
     2.5.2      17.1.11   6.11.1
     2.5.1      17.0.11   6.11.0
     2.5.0      16.2.10   6.10.2


3. Autoconf Code Fragment
-------------------------

Lars  Clausen contributed  the  following autoconf  fragment to  check
which version of FreeType is installed on a system (now updated to use
`pkg-config'  instead of  `freetype-config').   This one  tests for  a
version that is at least 2.10.2; you should change it to check against
other release numbers.


  AC_MSG_CHECKING([whether FreeType version is 2.10.2 or higher])
  old_CPPFLAGS="$CPPFLAGS"
  CPPFLAGS=`pkg-config freetype2 --cflags`
  AC_TRY_CPP([

#include <ft2build.h>
#include <freetype/freetype.h>

#if FREETYPE_MAJOR*10000 + FREETYPE_MINOR*100 + FREETYPE_PATCH < 21002
#  error FreeType version too low.
#endif

  ],
  [AC_MSG_RESULT(yes)
   FREETYPE_LIBS=`pkg-config freetype2 --libs`
   AC_SUBST(FREETYPE_LIBS)
   AC_DEFINE(HAVE_FREETYPE,1,[Define if you have the FreeType2 library])
   CPPFLAGS="$old_CPPFLAGS"],
  [AC_MSG_ERROR([Need FreeType library version 2.10.2 or higher])])

----------------------------------------------------------------------

Copyright (C) 2002-2021 by
David Turner, Robert Wilhelm, and Werner Lemberg.

This  file is  part of  the FreeType  project, and  may only  be used,
modified,  and distributed  under the  terms of  the FreeType  project
license,  LICENSE.TXT.  By  continuing to  use, modify,  or distribute
this file you  indicate that you have read the  license and understand
and accept it fully.


--- end of VERSIONS.TXT ---
