ref: 6cda9c489d2cc4841932551363c87fbc647d5357
dir: /docs/CUSTOMIZE/
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
The file found in "include/freetype/config/ftmodule.h" contains a list
of names corresponding to the modules and font drivers to be
statically compiled in the FreeType library during the build.
You can change it to suit your own preferences. Be aware that certain
modules depend on others, as described by the file "modules.txt" in
this directory.
You can modify the file's content to suit your needs, or override it
at compile time with one of the methods described below.
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 two ways to do
that:
1. 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".
2. Re-defining 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.
--- end of CUSTOMIZE ---