This section describes how to integrate the compiling and linking of programs using libgutenprint with build scripts. Commonly used systems include make, but often Makefile files are generated by using tools such as autoconf and automake.
Depending on the nature of the computer system Gutenprint was
installed on, as well as the options passed to
configure when configuring the package when
it was built, the CFLAGS and
LIBS parameters needed to compile and link
programs with libgutenprint may vary. To make it simple to
determine what these are on any given system, a
pkg-config datafile was created when
Gutenprint was built. pkg-config will
output the correct parameters for the setup on your system.
See the
pkg-config(1) manual page for a compete synopsis.
The correct CFLAGS to use can be obtained
with the --cflags option:
$ pkg-config --cflags gutenprint -I/usr/local/include |
The correct LIBS to use can the obtained
with the --libs option:
$ pkg-config --libs gutenprint -L/usr/local/lib -lgutenprint -lm -ldl |
Lastly, the installed version of Gutenprint can be obtained with the
--version option:
$ pkg-config --modversion gutenprint 4.3.23 |
The command can be used from the shell by enclosing it in backquotes ‘`’:
$ gcc `pkg-config --cflags gutenprint` -c stpimage.c $ gcc `pkg-config --libs gutenprint` -o stpimage stpimage.o |
However, this is not the way it it typically used. Normally it is used in a Makefile or by an m4 macro in a configure script.
If you use make with your own Makefile files, then you are on your own. This manual offers no assistance with doing this. Only the following suggestion is offered, for use with GNU make:
GUTENPRINT_VERSION = $(shell pkg-config --version gutenprint) GUTENPRINT_CFLAGS = $(shell pkg-config --cflags gutenprint) GUTENPRINT_LIBS = $(shell pkg-config --libs gutenprint) |
How you choose to use these variables is entirely up to you. See the GNU make manual for more information.
The autoconf program produces a Bourne shell script called configure from a template file called configure.ac. configure.ac contains both Bourne shell script, and m4 macros. autoconf expands the m4 macros into ‘real’ shell script. The resulting configure script performs various checks for installed programs, compiler characteristics and other system information such as available headers and libraries. See the GNU autoconf manual for more information.
pkg-config provides an m4 macro,
PKG_CHECK_MODULES, suitable for use in a
configure.ac script. It defines the
environment variables required for building libgutenprint-based
programs. For example, to set GUTENPRINT_CFLAGS and
GUTENPRINT_LIBS:
The automake program can be used to
generate Makefile.in files suitable for
use with a configure script generated by
autoconf. As automake
requires autoconf,
this section will assume the use of a
configure.ac script which uses the
PKG_CHECK_MODULES macro described above
(there is little point in not using it!).
It is highly recommended that you use GNU
autoconf and
automake. They will allow you to make your
software build on most platforms with most compilers.
automake makes writing complex
Makefile's very easy, by expressing how
to build your packages in terms of what files are required to
build a project and the installation locations of the files.
It imposes a few limitations over using plain
Makefile's, such as in the use of
conditionals, but these problems are vastly outweighed by the
benefits it brings. It also creates many extra targets in the
generated Makefile.in files such as
dist, distcheck,
clean, distclean,
maintainer-clean and tags,
and there are many more more available. See the GNU
automake manual for more information.
Because PKG_CHECK_MODULES calls
AC_SUBST to substitute
GUTENPRINT_CFLAGS and
GUTENPRINT_LIBS, automake
will automatically set these variables in the
Makefile.in files it generates, requiring
no additional effort on your part!
As in previous examples, we will make a program stpimage from stpimage.c. This is how one might build write a Makefile.am to do this:
@SET_MAKE@ AM_CFLAGS = $(GUTENPRINT_CFLAGS) bin_PROGRAMS = stpimage stpimage_SOURCES = stpimage.c stpimage_LDADD = $(GUTENPRINT_LIBS) MAINTAINERCLEANFILES = Makefile.in |
That's all there is to it! Please note that this example also
requires the macro AC_PROG_MAKE_SET to be
used in configure.ac.