mirror of https://github.com/freetype/freetype
153 lines
5.2 KiB
Plaintext
153 lines
5.2 KiB
Plaintext
How to customize the compilation of the library
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===============================================
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FreeType is highly customizable to fit various needs, and this
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document describes how it is possible to select options and
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components at compilation time.
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I. Configuration macros
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The file `include/freetype/config/ftoption.h' contains a list of
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commented configuration macros that can be toggled by developers to
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indicate which features should be active while building the library.
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These options range from debug level to availability of certain
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features, like native TrueType hinting through a bytecode
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interpreter.
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We invite you to read this file for more information. You can
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change the file's content to suit your needs, or override it with
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one of the techniques described below.
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II. Modules list
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If you use GNU make please edit the top-level file `modules.cfg'.
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It contains a list of available FreeType modules and extensions to
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be compiled. Change it to suit your own preferences. Be aware that
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certain modules depend on others, as described in the file. GNU
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make uses `modules.cfg' to generate `ftmodule.h' (in the object
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directory).
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If you build FreeType in a directory separate from the source files,
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put your customized `modules.cfg' in that directory; that way you
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can keep the source files `clean'.
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If you don't use GNU make you have to manually edit the file
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`include/freetype/config/ftmodule.h' (which is *not* used with if
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compiled with GNU make) to add or remove the drivers and components
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you want to compile into the library. See `INSTALL.ANY' for more
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information.
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III. System interface
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FreeType's default interface to the system (i.e., the parts that
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deal with memory management and i/o streams) is located in
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`src/base/ftsystem.c'.
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The current implementation uses standard C library calls to manage
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memory and to read font files. It is however possible to write
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custom implementations to suit specific systems.
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To tell the GNU Make-based build system to use a custom system
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interface, you have to define the environment variable FTSYS_SRC to
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point to the relevant implementation:
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on Unix:
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./configure <your options>
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export FTSYS_SRC=foo/my_ftsystem.c
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make
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make install
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on Windows:
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make setup <compiler>
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set FTSYS_SRC=foo/my_ftsystem.c
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make
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IV. Overriding default configuration and module headers
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It is possible to override the default configuration and module
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headers without changing the original files. There are three ways
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to do that:
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1. With GNU make
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[This is actually a combination of method 2 and 3.]
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Just put your custom `ftoption.h' file into the objects directory
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(normally `<topdir>/objs' if you build in the source tree, or the
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directory where you invoke configure if you build in a separate
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directory), which GNU make prefers over the standard location. No
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action is needed for `ftmodule.h' because it is generated
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automatically in the objects directory.
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2. Using the C include path
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Use the C include path to ensure that your own versions of the
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files are used at compile time when the lines
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#include FT_CONFIG_OPTIONS_H
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#include FT_CONFIG_MODULES_H
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are compiled. Their default values being
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<freetype/config/ftoption.h> and <freetype/config/ftmodule.h>, you
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can do something like:
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custom/
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config/
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ftoption.h => custom options header
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ftmodule.h => custom modules list
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include/ => normal FreeType 2 include
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...
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then change the C include path to always give the path to `custom'
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before the FreeType 2 `include'.
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3. Redefining FT_CONFIG_OPTIONS_H and FT_CONFIG_MODULES_H
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Another way to do the same thing is to redefine the macros used to
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name the configuration headers. To do so, you need a custom
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`ft2build.h' whose content can be as simple as:
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#ifndef FT2_BUILD_MY_PLATFORM_H_
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#define FT2_BUILD_MY_PLATFORM_H_
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#define FT_CONFIG_OPTIONS_H <custom/my-ftoption.h>
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#define FT_CONFIG_MODULES_H <custom/my-ftmodule.h>
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#include <freetype/config/ftheader.h>
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#endif /* FT2_BUILD_MY_PLATFORM_H_ */
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Place those files in a separate directory, e.g.,
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custom/
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ft2build.h => custom version described above
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my-ftoption.h => custom options header
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my-ftmodule.h => custom modules list header
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and change the C include path to ensure that `custom' is always
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placed before the FT2 `include' during compilation.
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----------------------------------------------------------------------
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Copyright (C) 2003-2021 by
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David Turner, Robert Wilhelm, and Werner Lemberg.
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This file is part of the FreeType project, and may only be used,
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modified, and distributed under the terms of the FreeType project
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license, LICENSE.TXT. By continuing to use, modify, or distribute
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this file you indicate that you have read the license and understand
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and accept it fully.
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--- end of CUSTOMIZE ---
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