Compiling the GTK+ libraries

Building GTK+ on UNIX-like systems

This chapter covers building and installing GTK+ on UNIX and UNIX-like systems such as Linux. Compiling GTK+ on Microsoft Windows is different in detail and somewhat more difficult to get going since the necessary tools aren't included with the operating system.

Before we get into the details of how to compile GTK+, we should mention that in many cases, binary packages of GTK+ prebuilt for your operating system will be available, either from your operating system vendor or from independent sources. If such a set of packages is available, installing it will get you programming wih GTK+ much faster than building it yourself. In fact, you may well already have GTK+ installed on your system already.

On UNIX-like systems GTK+ uses the standard GNU build system, using autoconf for package configuration and resolving portability issues, automake for building makefiles that comply with the GNU Coding Standards, and libtool for building shared libraries on multiple platforms.

If you are building GTK+ from the distributed source packages, then won't need these tools installed; the necessary pieces of the tools are already included in the source packages. But it's useful to know a bit about how packages that use these tools work. A source package is distributed as a tar.gz or tar.bz2 file which you unpack into a directory full of the source files as follows:

      tar xvfz gtk+-2.0.0.tar.gz
      tar xvfj gtk+-2.0.0.tar.bz2

In the toplevel of the directory that is created, there will be a shell script called configure which you then run to take the template makefiles called Makefile.in in the package and create makefiles customized for your operating system. The configure script can be passed various command line arguments to determine how the package is built and installed. The most commonly useful argument is the --prefix argument which determines where the package is installed. To install a package in /opt/gtk you would run configure as:

      ./configure --prefix=/opt/gtk

A full list of options can be found by running configure with the --help argument. In general, the defaults are right and should be trusted. After you've run configure, you then run the make command to build the package and install it.

      make
      make install

If you don't have permission to write to the directory you are installing in, you may have to change to root temporarily before running make install. Also, if you are installing in a system directory, on some systems (such as Linux), you will need to run ldconfig after make install so that the newly installed libraries will be found.

Several environment variables are useful to pass to set before running configure. CPPFLAGS contains options to pass to the C compiler, and is used to tell the compiler where to look for include files. The LDFLAGS variable is used in a similar fashion for the linker. Finally the PKG_CONFIG_PATH environment variable contains a search path that pkg-config (see below) uses when looking for for file describing how to compile programs using different libraries. If you were installing GTK+ and it's dependencies into /opt/gtk, you might want to set these variables as:

      CPPFLAGS="-I/opt/gtk/include"
      LDFLAGS="-L/opt/gtk/lib"
      PKG_CONFIG_PATH="/opt/gtk/lib/pkgconfig"
      export CPPFLAGS LDFLAGS PKG_CONFIG_PATH

You may also need to set the LD_LIBRARY_PATH environment variable so the systems dynamic linker can find the newly installed libraries, and the PATH environment program so that utility binaries installed by the various libraries will be found.

      LD_LIBRARY_PATH="/opt/gtk/lib"
      PATH="/opt/gtk/bin:$PATH"
      export LD_LIBRARY_PATH PATH

Dependencies

Before you can compile the GTK+ widget toolkit, you need to have various other tools and libraries installed on your system. The two tools needed during the build process (as differentiated from the tools used in when creating GTK+ mentioned above such as autoconf) are pkg-config and GNU make.

pkg-config is a tool for tracking the compilation flags needed for libraries that are used by the GTK+ libraries. (For each library, a small .pc text file is installed in a standard location that contains the compilation flags needed for that library along with version number information.) The version of pkg-config needed to build GTK+ is mirrored in the dependencies directory on the GTK+ FTP site.
The GTK+ makefiles will mostly work with different versions of make, however, there tends to be a few incompatibilities, so the GTK+ team recommends installing GNU make if you don't already have it on your system and using it. (It may be called gmake rather than make.)

Three of the libraries that GTK+ depends on are maintained by by the GTK+ team: GLib, Pango, and ATK. Other libraries are maintained separately.

The GLib library provides core non-graphical functionality such as high level data types, Unicode manipulation, and an object and type system to C programs. It is available from the GTK+ FTP site.
Pango is a library for internationalized text handling. It is available from the GTK+ FTP site..
ATK is the Accessibility Toolkit. It provides a set of generic interfaces allowing accessibility technologies such as screen readers to interact with a graphical user interface. It is available from the GTK+ FTP site.
The GNU libiconv library is needed to build GLib if your system doesn't have the iconv() function for doing conversion between character encodings. Most modern systems should have iconv().
The libintl library from the GNU gettext package is needed if your system doesn't have the gettext() functionality for handling message translation databases.
The JPEG, PNG, and TIFF image loading libraries are needed to compile GTK+. You probably already have these libraries installed, but if not, the versions you need are available in the dependencies directory on the the GTK+ FTP site.. (Before installing these libraries from source, you should check if your operating system vendor has prebuilt packages of these libraries that you don't have installed.)
The libraries from the X window system are needed to build Pango and GTK+. You should already have these installed on your system, but it's possible that you'll need to install the development environment for these libraries that your operating system vendor provides.
The fontconfig library provides Pango with a standard way of locating fonts and matching them against font names.
Cairo is a graphics library that supports vector graphics and image compositing. Both Pango and GTK+ use cairo for much of their drawing.

Building and testing GTK+

First make sure that you have the necessary external dependencies installed: pkg-config, GNU make, the JPEG, PNG, and TIFF libraries, FreeType, and, if necessary, libiconv and libintl. To get detailed information about building these packages, see the documentation provided with the individual packages. On a Linux system, it's quite likely you'll have all of these installed already except for pkg-config.

Then build and install the GTK+ libraries in the order: GLib, Pango, ATK, then GTK+. For each library, follow the steps of configure, make, make install mentioned above. If you're lucky, this will all go smoothly, and you'll be ready to start compiling your own GTK+ applications. You can test your GTK+ installation by running the gtk-demo program that GTK+ installs.

If one of the configure scripts fails or running make fails, look closely at the error messages printed; these will often provide useful information as to what went wrong. When configure fails, extra information, such as errors that a test compilation ran into, is found in the file config.log. Looking at the last couple of hundred lines in this file will frequently make clear what went wrong. If all else fails, you can ask for help on the gtk-list mailing list. See Mailing lists and bug reports(3) for more information.

Extra Configuration Options

In addition to the normal options, the configure script for the GTK+ library supports a number of additional arguments. (Command line arguments for the other GTK+ libraries are described in the documentation distributed with the those libraries.)

--disable-modules and --enable-modules. Normally GTK+ will try to build the GdkPixbuf image file format loaders as little shared libraries that are loaded on demand. The --disable-modules argument indicates that they should all be built statically into the GTK+ library instead. This is useful for people who need to produce statically-linked binaries. If neither --disable-modules nor --enable-modules is specified, then the configure script will try to auto-detect whether shared modules work on your system.

--with-included-loaders. This option allows you to specify which image loaders you want to include; for example, you might include only the PNG loader to create a smaller GdkPixbuf binary.

--enable-debug. Turns on various amounts of debugging support. Setting this to 'no' disables g_assert(), g_return_if_fail(), g_return_val_if_fail() and all cast checks between different object types. Setting it to 'minimum' disables only cast checks. Setting it to 'yes' enables runtime debugging. The default is 'minimum'. Note that 'no' is fast, but dangerous as it tends to destabilize even mostly bug-free software by changing the effect of many bugs from simple warnings into fatal crashes. Thus --enable-debug=no should not be used for stable releases of GTK+.

--disable-visibility and --enable-visibility. The option --disable-visibility turns off the use of ELF visibility attributes for linking optimizations. This makes sense while changing GTK+ itself, since the way in which GTK+ uses visibility attributes forces a full rebuild of all source files for any header modification.

--enable-explicit-deps and --disable-explicit-deps. If --enable-explicit-deps is specified then GTK+ will write the full set of libraries that GTK+ depends upon into its .pc files to be used when programs depending on GTK+ are linked. Otherwise, GTK+ only will include the GTK+ libraries themselves, and will depend on system library dependency facilities to bring in the other libraries. By default GTK+ will disable explicit dependencies unless it detects that they are needed on the system. (If you specify --enable-static to force building of static libraries, then explicit dependencies will be written since library dependencies don't work for static libraries.) Specifying --enable-explicit-deps or --enable-static can cause compatibility problems when libraries that GTK+ depends upon change their versions, and should be avoided if possible.

--disable-shm and --enable-shm. These options can be used to control whether GTK+ will use shared memory to communicate with the X server when possible. The default is 'yes'.

--disable-xim and --enable-xim. These options can be used to control whether GTK+ will be compiled with support for XIM. (The X Input Method extension, used for Japanese input.) The default is yes.

--disable-xim-inst and --enable-xim-inst. These options determine whether GTK+ will use the XIM instantiate callback. The default is 'yes', unless the host system is Solaris, where XRegisterIMInstantiateCallback() seems to cause a segfault.

--disable-xkb and --enable-xkb. By default the configure script will try to auto-detect whether the XKB extension is supported by the X libraries GTK+ is linked with. These options can be used to explicitly control whether GTK+ will support the XKB extension.

--disable-xinerama and --enable-xinerama. By default the configure script will try to link against the Xinerama libraries if they are found. These options can be used to explicitly control whether Xinerama should be used.

--disable-gtk-doc and --enable-gtk-doc. The gtk-doc package is used to generate the reference documentation included with GTK+. By default support for gtk-doc is disabled because it requires various extra dependencies to be installed. If you have gtk-doc installed and are modifying GTK+, you may want to enable gtk-doc support by passing in --enable-gtk-doc. If not enabled, pre-generated HTML files distributed with GTK+ will be installed.

--with-xinput. Controls whether GTK+ is built with support for the XInput extension. The XInput extension provides an interface to extended input devices such as graphics tablets. When this support is compiled in, specially written GTK+ programs can get access to subpixel positions, multiple simultaneous input devices, and extra "axes" provided by the device such as pressure and tilt information. This is only known to work well on XFree86 systems, though other systems do have this extension.

--with-gdktarget. Toggles between the supported backends for GDK. The default is x11, unless the platform is Windows, in which case the default is win32. Other supported backends are the quartz backend for OS X, and the DirectFB backend for the Linux framebuffer.