This section describes how to integrate the compiling and linking of programs using libgimpprint 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 Gimp-Print 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 libgimpprint may vary. To make it simple to determine what these are on any given system, a pkg-config datafile was created when Gimp-Print 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 gimpprint -I/usr/local/include |
The correct LIBS to use can the obtained with the --libs option:
$ pkg-config --libs gimpprint -L/usr/local/lib -lgimpprint -lm -ldl |
Lastly, the installed version of Gimp-Print can be obtained with the --version option:
$ pkg-config --modversion gimpprint 4.3.23 |
The command can be used from the shell by enclosing it in backquotes ‘`’:
$ gcc `pkg-config --cflags gimpprint` -c stpimage.c $ gcc `pkg-config --libs gimpprint` -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:
GIMPPRINT_VERSION = $(shell pkg-config --version gimpprint) GIMPPRINT_CFLAGS = $(shell pkg-config --cflags gimpprint) GIMPPRINT_LIBS = $(shell pkg-config --libs gimpprint) |
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 libgimpprint-based
programs. For example, to set GIMPPRINT_CFLAGS and
GIMPPRINT_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
GIMPPRINT_CFLAGS and
GIMPPRINT_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:
AUTOMAKE_OPTIONS = 1.7 gnu MAINT_CHARSET = latin1 @SET_MAKE@ AM_CFLAGS = $(GIMPPRINT_CFLAGS) bin_PROGRAMS = stpimage stpimage_SOURCES = stpimage.c stpimage_LDADD = $(GIMPPRINT_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.