modules/freetype2/docs/CUSTOMIZE
author Robert O'Callahan <robert@ocallahan.org>
Fri, 12 Feb 2010 14:11:30 +1300
changeset 38091 f12473882d84252401d963ec0a2898f79274559e
parent 22693 9e5b08f9e9d96d15872c7b8c60312bb579be4115
child 137177 9426f36c2b774e2a48496b00c6b9e5ef83ea03ce
permissions -rw-r--r--
Backing out bug 541406 due to test failure

How to customize the compilation of the library
===============================================

  FreeType  is highly  customizable  to fit  various  needs, and  this
  document  describes  how  it  is  possible  to  select  options  and
  components at compilation time.


I. Configuration macros

  The  file found  in `include/freetype/config/ftoption.h'  contains a
  list  of  commented configuration  macros  that  can  be toggled  by
  developers  to  indicate  which  features  should  be  active  while
  building the library.

  These  options range  from debug  level to  availability  of certain
  features,   like  native   TrueType  hinting   through   a  bytecode
  interpreter.

  We  invite you  to read  this file  for more  information.   You can
  change the  file's content to suit  your needs, or  override it with
  one of the techniques described below.


II. Modules list

  If you  use GNU make  please edit the top-level  file `modules.cfg'.
  It contains a  list of available FreeType modules  and extensions to
  be compiled.  Change it to suit your own preferences.  Be aware that
  certain modules  depend on  others, as described  in the  file.  GNU
  make  uses `modules.cfg'  to  generate `ftmodule.h'  (in the  object
  directory).

  If  you don't  use  GNU make  you  have to  manually  edit the  file
  `include/freetype/config/ftmodule.h'  (which is  *not* used  with if
  compiled with GNU make) to  add or remove the drivers and components
  you want  to compile into  the library.  See `INSTALL.ANY'  for more
  information.


III. System interface

  FreeType's  default interface to  the system  (i.e., the  parts that
  deal  with  memory  management   and  i/o  streams)  is  located  in
  `src/base/ftsystem.c'.

  The current  implementation uses standard C library  calls to manage
  memory  and to read  font files.   It is  however possible  to write
  custom implementations to suit specific systems.

  To  tell the  GNU Make-based  build system  to use  a  custom system
  interface, you have to  define the environment variable FTSYS_SRC to
  point to the relevant implementation:

    on Unix:

      ./configure <your options>
      export FTSYS_SRC=foo/my_ftsystem.c
      make
      make install

    on Windows:

      make setup <compiler>
      set FTSYS_SRC=foo/my_ftsystem.c
      make


IV. Overriding default configuration and module headers

  It  is possible  to override  the default  configuration  and module
  headers without  changing the original files.  There  are three ways
  to do that:


  1. With GNU make

    [This is actually a combination of method 2 and 3.]

    Just put your custom  `ftoption.h' file into the objects directory
    (normally  `<topdir>/objs'),  which  GNU  make  prefers  over  the
    standard location.   No action is needed  for `ftmodule.h' because
    it is generated automatically in the objects directory.


  2. Using the C include path

    Use the  C include path  to ensure that  your own versions  of the
    files are used at compile time when the lines

      #include FT_CONFIG_OPTIONS_H
      #include FT_CONFIG_MODULES_H

    are      compiled.       Their      default      values      being
    <freetype/config/ftoption.h> and <freetype/config/ftmodule.h>, you
    can do something like:

      custom/
        freetype/
          config/
            ftoption.h    => custom options header
            ftmodule.h    => custom modules list

      include/            => normal FreeType 2 include
        freetype/
          ...

    then change the C include path to always give the path to `custom'
    before the FreeType 2 `include'.


  3. Redefining FT_CONFIG_OPTIONS_H and FT_CONFIG_MODULES_H

    Another way to do the same thing is to redefine the macros used to
    name  the configuration  headers.  To  do  so, you  need a  custom
    `ft2build.h' whose content can be as simple as:

      #ifndef __FT2_BUILD_MY_PLATFORM_H__
      #define __FT2_BUILD_MY_PLATFORM_H__

      #define FT_CONFIG_OPTIONS_H  <custom/my-ftoption.h>
      #define FT_CONFIG_MODULES_H  <custom/my-ftmodule.h>

      #include <freetype/config/ftheader.h>

      #endif /* __FT2_BUILD_MY_PLATFORM_H__ */

    Place those files in a separate directory, e.g.,

      custom/
        ft2build.h           => custom version described above
        my-ftoption.h        => custom options header
        my-ftmodule.h        => custom modules list header

    and change  the C include path  to ensure that  `custom' is always
    placed before the FT2 `include' during compilation.

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

Copyright 2003, 2005, 2006 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 CUSTOMIZE ---