Compiling the GTK+ libraries

Compiling the GTK+ Libraries —
How to compile GTK+ itself

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. <!--more-->

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 file which you unpack into a
directory full of the source files as follows:

      tar xvfz gtk+-2.0.0.tar.gz

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.)

configure [[–disable-modules] | [–enable-modules]] [[–with-included-loaders==LOADER1,LOADER2,…]] [[–enable-debug=[no|minimum|yes]]] [[–disable-visibility] | [–enable-visibility]] [[–disable-shm] | [–enable-shm]] [[–disable-xim] | [–enable-xim]] [[–disable-xim-inst] | [–enable-xim-inst]] [[–disable-xkb] | [–enable-xkb]] [[–disable-gtk-doc] | [–enable-gtk-doc]] [[–with-xinput=[no|yes]]] [[–with-gdktarget=[x11|linux-fb|win32]]] [[–disable-shadowfb] | [–enable-shadowfb]]

–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-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.

–disable-shadowfb and
–enable-shadowfb.

Toggles shadow framebuffer support for the linux-fb target,
if selected.

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