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.


I. Version & Release numbers:

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

  * the official FT2 release number, like 2.0.9, or 2.1.3

  * the libtool (and Unix) specific version number, like "9.2.3". This
    is what "freetype-config --version" will return

  * the platform-specific shared object number, used for example when
    the library is installed as "/usr/lib/libfreetype.so.6.3.2"


the platform-specific number is, unsurprisingly, platform-specific and varies
with the operating system you're 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 FT_FREETYPE_H:

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

see below for some Autoconf fragment to


the release number is also available at *runtime* through the
"FT_Library_Version" API. Unfortunately, this one wasn't available or
working correctly before the 2.1.3 official release !!


II. Table:

the following is a simple table that gives, for each official release,
the corresponding libtool number, as well as the shared object number
found on _most_ systems, but not all of them:

  release       libtool        so
-------------------------------------
   2.1.4         9.3.3         6.3.3
   2.1.3         9.2.3         6.3.2
   2.1.2         9.1.3         6.3.1
   2.1.1         9.0.3          ?
   2.1.0         8.0.2          ?
   2.0.9         9.0.3          ?
   2.0.8         8.0.2          ?

the libtool numbers are a bit inconsistent due to the library's history:

  - 2.1.0 was created as a development branch from 2.0.8
    (hence the same libtool numbers)

  - 2.0.9 was a bug-fix release of the "stable" branch, we
    apparently incorrectly increased its libtool number

  - 2.1.4 is still in the "development" branch, however it's stable enough
    to be the basis of an upcoming 2.2.0 release


III. AutoConf Code Fragment:

Lars Clausen contributed the following Autoconf fragment to detect at
which version of FreeType is installed on your system. This one tests
for a version that is at least 2.0.9, you should change the last line to
check against other release numbers.

    AC_MSG_CHECKING([for version of FreeType])
    FREETYPE_INCLUDE=`freetype-config --cflags | cut -c3-`
    FREETYPE_MAJOR=`grep '^#define FREETYPE_MAJOR' $FREETYPE_INCLUDE/freetype/freetype.h | cut -d' ' -f3`
    FREETYPE_MINOR=`grep '^#define FREETYPE_MINOR' $FREETYPE_INCLUDE/freetype/freetype.h | cut -d' ' -f3`
    FREETYPE_PATCH=`grep '^#define FREETYPE_PATCH' $FREETYPE_INCLUDE/freetype/freetype.h | cut -d' ' -f3`
    FREETYPE_VERSION=`echo | awk "BEGIN { printf \"%d\", ($FREETYPE_MAJOR * 1000 + $FREETYPE_MINOR) * 1000 + $FREETYPE_PATCH;}"`
    AC_MSG_RESULT([$FREETYPE_MAJOR.$FREETYPE_MINOR.$FREETYPE_PATCH])
    if test "$FREETYPE_VERSION" -ge 2000009; then