Gtk – 4.0: Compiling the GTK Libraries
Description: Reference for Gtk-4.0: Compiling the GTK Libraries

## Building GTK

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 with GTK much faster than building it yourself. In fact, you may well already have GTK installed on your system already.

In order to build GTK, you will need meson installed on your system. On Linux, and other UNIX-like operating systems, you will also need ninja. This guide does not cover how to install these two requirements, but you can refer to the Meson website for more information. The Ninja build tool is also usable on various operating systems, so we will refer to it in the examples.

If you are building GTK from a source distribution or from a Git clone, you will need to use meson to configure the project. The most commonly useful argument is the `--prefix` one, which determines where the files will go once installed. To install GTK under a prefix like `/opt/gtk` you would run Meson as:

    meson setup --prefix /opt/gtk builddir

Meson will create the `builddir` directory and place all the build artefacts there.

You can get a list of all available options for the build by running `meson configure`.

After Meson successfully configured the build directory, you then can run the build, using Ninja:

    cd builddir
    ninja
    ninja 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 `ninja install`.

Several environment variables are useful to pass to set before running meson. `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 files 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

## Build types

Meson has different build types, exposed by the `buildtype` configuration option. GTK enables and disables functionality depending on the build type used when calling meson to configure the build.

### Debug builds

GTK will enable debugging code paths in both the `debug` and `debugoptimized` build types. Builds with `buildtype` set to `debug` will additionally enable consistency checks on the internal state of the toolkit.

It is recommended to use the `debug` or `debugoptimized` build types when developing GTK itself. Additionally, `debug` builds of GTK are recommended for profiling and debugging GTK applications, as they include additional validation of the internal state.

The `debugoptimized` build type is the default for GTK if no build type is specified when calling meson.

### Release builds

The `release` build type will disable debugging code paths and additional run time safeties, like checked casts for object instances.

The `plain` build type provided by Meson should only be used when packaging GTK, and it’s expected that packagers will provide their own compiler flags when building GTK. See the previous section for the list of environment variables to be used to define compiler and linker flags. Note that with the plain build type, you are also responsible for controlling the debugging features of GTK with `-DG_ENABLE_DEBUG` and `-DG_DISABLE_CAST_CHECKS`.

## Dependencies

Before you can compile the GTK widget toolkit, you need to have various other tools and libraries installed on your system. Dependencies of GTK have their own build systems, so you will need to refer to their own installation instructions.

A particular important tool used by GTK to find its dependencies is `pkg-config`.

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.)

Some of the libraries that GTK depends on are maintained by the GTK team: GLib, GdkPixbuf, Pango, and GObject Introspection. 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 here.
- The GdkPixbuf library provides facilities for loading images in a variety of file formats. It is available here.
- Pango is a library for internationalized text handling. It is available here.
- GObject Introspection is a framework for making introspection data available to language bindings. It is available here.
- 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 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 drawing. Note that we also need the auxiliary cairo-gobject library.
- libepoxy is a library that abstracts the differences between different OpenGL libraries. GTK uses it for cross-platform GL support and for its own drawing.
- Graphene is a library that provides vector and matrix types for 2D and 3D transformations. GTK uses it internally for drawing.
- The Wayland libraries are needed to build GTK with the Wayland backend.
- The shared-mime-info package is not a hard dependency of GTK, but it contains definitions for mime types that are used by GIO and, indirectly, by GTK. gdk-pixbuf will use GIO for mime type detection if possible. For this to work, shared-mime-info needs to be installed and `XDG_DATA_DIRS` set accordingly at configure time. Otherwise, gdk-pixbuf falls back to its built-in mime type detection.

## Building and testing GTK

First make sure that you have the necessary external dependencies installed: `pkg-config`, Meson, Ninja, 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 any average Linux system, it’s quite likely you’ll have all of these installed already, or they will be easily accessible through your operating system package repositories.

Then build and install the GTK libraries in the order: GLib, Cairo, Pango, then GTK. For each library, follow the instructions they provide, and make sure to share common settings between them and the GTK build; if you are using a separate prefix for GTK, for instance, you will need to use the same prefix for all its dependencies you build. 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 `gtk4-demo` program that GTK installs.

If one of the projects you’re configuring or building fails, look closely at the error messages printed; these will often provide useful information as to what went wrong. Every build system has its own log that can help you understand the issue you’re encountering. If all else fails, you can ask for help on the GTK forums.

## Extra Configuration Options

In addition to the normal options provided by Meson, GTK defines various arguments that modify what should be built. All of these options are passed to `meson` as `-Doption=value`. Most of the time, the value can be `true` or `false`, or `enabled`, `disabled` or `auto`.

To see a summary of all supported options and their allowed values, run

    meson configure builddir

### `x11-backend`, `win32-backend`, `broadway-backend`, `wayland-backend` and `macos-backend`

Enable specific backends for GDK. If none of these options are given, the Wayland backend will be enabled by default, if the platform is Linux; the X11 backend will also be enabled by default, unless the platform is Windows, in which case the default is win32, or the platform is macOS, in which case the default is macOS. If any backend is explicitly enabled or disabled, no other platform will be enabled automatically.

### `vulkan`

By default, GTK will try to build with support for the Vulkan graphics API in addition to cairo and OpenGL. This option can be used to explicitly control whether Vulkan should be used.

### `media-gstreamer` and `media-ffmpeg`

By default, GTK will try to build the gstreamer backend for media playback support. These options can be used to explicitly control which media backends should be built.

### `print-cups` and `print-cpdb`

By default, GTK will try to build the cups and file print backends if their dependencies are found. These options can be used to explicitly control which print backends should be built.

### `cloudproviders`

This option controls whether GTK should use libcloudproviders for supporting various Cloud storage APIs in the file chooser.

### `sysprof`

This option controls whether GTK should include support for tracing with sysprof.

### `tracker`

This option controls whether GTK should use Tracker for search support in the file chooser.

### `colord`

This option controls whether GTK should use colord for color calibration support in the cups print backend.

### `gtk_doc`, `man-pages` and `update_screenshots`

The gi-docgen package is used to generate the reference documentation included with GTK. By default support for gi-docgen is disabled because it requires various extra dependencies to be installed. Introspection needs to be enabled, since the documentation is generated from introspection data.

### `introspection`

Allows to disable building introspection support. This is option is mainly useful for shortening turnaround times on developer systems. Installed builds of GTK should always have introspection support.

### `build-testsuite`

If you want to run the testsuite to ensure that your GTK build works, you should enable it with this option.

### `build-tests`, `build-examples`, `demos`

By default, GTK will build quite a few tests, examples and demos. While these are useful on a developer system, they are not needed when GTK is built e.g. for a flatpak runtime. These options allow to disable building tests and demos.