Compiling GTK Applications on UNIX

To compile a GTK application, you need to tell the compiler where to find the GTK header files and libraries. This is done with the pkg-config utility.

The following interactive shell session demonstrates how pkg-config is used (the actual output on your system may be different):

$ pkg-config --cflags gtk+-3.0
 -pthread -I/usr/include/gtk-3.0 -I/usr/lib64/gtk-3.0/include -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12
$ pkg-config --libs gtk+-3.0
 -pthread -lgtk-3 -lgdk-3 -latk-1.0 -lgio-2.0 -lpangoft2-1.0 -lgdk_pixbuf-2.0 -lpangocairo-1.0 -lcairo -lpango-1.0 -lfreetype -lfontconfig -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lrt -lglib-2.0

The simplest way to compile a program is to use the “backticks” feature of the shell. If you enclose a command in backticks (not single quotes), then its output will be substituted into the command line before execution. So to compile a GTK Hello, World, you would type the following:

$ cc `pkg-config --cflags gtk+-3.0` hello.c -o hello `pkg-config --libs gtk+-3.0`

Deprecated GTK functions are annotated to make the compiler emit warnings when they are used (e.g. with gcc, you need to use the -Wdeprecated-declarations option). If these warnings are problematic, they can be turned off by defining the preprocessor symbol GDK_DISABLE_DEPRECATION_WARNINGS by using the commandline option -DGDK_DISABLE_DEPRECATION_WARNINGS

GTK deprecation annotations are versioned; by defining the macros GDK_VERSION_MIN_REQUIRED and GDK_VERSION_MAX_ALLOWED, you can specify the range of GTK versions whose API you want to use. APIs that were deprecated before or introduced after this range will trigger compiler warnings.

Here is how you would compile hello.c if you want to allow it to use symbols that were not deprecated in 3.2:

$ cc `pkg-config --cflags gtk+-3.0` -DGDK_VERSION_MIN_REQIRED=GDK_VERSION_3_2 hello.c -o hello `pkg-config --libs gtk+-3.0`

And here is how you would compile hello.c if you don’t want it to use any symbols that were introduced after 3.4:

$ cc `pkg-config --cflags gtk+-3.0` -DGDK_VERSION_MAX_ALLOWED=GDK_VERSION_3_4 hello.c -o hello `pkg-config --libs gtk+-3.0`

The older deprecation mechanism of hiding deprecated interfaces entirely from the compiler by using the preprocessor symbol GTK_DISABLE_DEPRECATED is still used for deprecated macros, enumeration values, etc. To detect uses of these in your code, use the commandline option -DGTK_DISABLE_DEPRECATED. There are similar symbols GDK_DISABLE_DEPRECATED, GDK_PIXBUF_DISABLE_DEPRECATED and G_DISABLE_DEPRECATED for GDK, GdkPixbuf and GLib, respectively.

Similarly, if you want to make sure that your program doesn’t use any functions which may be problematic in a multidevice setting, you can define the preprocessor symbol GDK_MULTIDEVICE_SAFE by using the command line option -DGTK_MULTIDEVICE_SAFE=1.

Useful autotools macros

GTK provides various macros for easily checking version and backends supported. The macros are

AM_PATH_GTK_3_0([minimum-version], [if-found], [if-not-found], [modules])

This macro should be used to check that GTK is installed and available for compilation. The four arguments are optional, and they are: minimum-version, the minimum version of GTK required for compilation; if-found, the action to perform if a valid version of GTK has been found; if-not-found, the action to perform if a valid version of GTK has not been found; modules, a list of modules to be checked along with GTK.

GTK_CHECK_BACKEND([backend-name], [minimum-version], [if-found], [if-not-found])

This macro should be used to check if a specific backend is supported by GTK. The minimum-version, if-found and if-not-found arguments are optional.