Get Involved/development/More

This page is the continuation with more advanced topics of the page Get_Involved/development.

Develop in a Linux container

When you start programming for KDE, it is recommended that you use kdesrc-build in your main operating system or in a virtual machine running on a Linux operating system that is better supported by kdesrc-build.

As an alternative, you can run kdesrc-build in a Linux container (docker, podman, toolbx, distrobox).

Option 1. The KDE PIM Docker image

You can install Docker and the KDE PIM Docker image. It provides a development environment that is isolated from your day-to-day system. It is based on KDE Neon Unstable.

Option 2. distrobox

It is possible to start developing KDE software using container images that are able to see inside your home folder. This can be done using distrobox and podman.

First, install distrobox and podman from your distribution repositories:

• Debian/Ubuntu: sudo apt install distrobox podman
• openSUSE: sudo zypper install distrobox podman
• Fedora: sudo dnf install distrobox podman
• Arch: sudo pacman --sync distrobox podman

Building without kdesrc-build

You can build a single repository using the KDE Neon Unstable docker image. We will be using the plasma:unstable image, which comes with the latest KDE software and libraries, and we will be using the minimal version, which requires you to install development libraries before compiling your projects.

After installing distrobox and podman, run the following to create a new distrobox container:

podman pull invent-registry.kde.org/neon/docker-images/plasma:unstable
distrobox create --image invent-registry.kde.org/neon/docker-images/plasma:unstable

This will create a distrobox container named plasma-unstable.

Note

The plasma:unstable image size is 5.6 GB.

Lastly, enter the generated container:

distrobox enter plasma-unstable

You can then just clone the desired repository in your home folder and build it while being inside the container. If any development libraries are missing, you can just install them the same way you would install on Debian/Ubuntu/KDE Neon:

sudo apt install packagename-dev

You can also use build-dep to let apt install the required libraries for the program you will be compiling. For example, to install the development libraries for Kate, you can run:

sudo apt-get build-dep kate

Building with kdesrc-build

First, install distrobox and podman from your distribution repositories. Then run:

distrobox enter

This should create a container based on your current Linux OS and enter it. It is preferable to use one of the Linux distributions that is better suited for kdesrc-build, as mentioned in this wiki page, so if your distribution does not provide very up-to-date packages, you can download and use a different container image for your distrobox from Dockerhub. For example, with openSUSE Tumbleweed:

podman pull opensuse/tumbleweed
distrobox create --image opensuse/tumbleweed --name tumbleweed
distrobox enter tumbleweed

Then it's a matter of downloading and running kdesrc-build as detailed in Get_Involved/development/Set_up_a_development_environment:

mkdir -p ~/kde/src
cd ~/kde/src
git clone https://invent.kde.org/sdk/kdesrc-build.git
cd kdesrc-build
./kdesrc-build --initial-setup
source ~/.bashrc

From this point on, one important thing to bear in mind is that a distrobox container is transparent in its user space and containerized in its root space: when you are inside a distrobox container, you can see the content of system's home folder, but not your system's root folders, only the container's root folders. This means that you can install packages inside the container using root privileges and access those packages to compile your programs stored in your home, without ever installing those packages in your actual system!

You can take advantage of this by installing, for instance, Qt development packages used for kdesrc-build from inside the container. This way, it is not necessary to compile Qt with kdesrc-build. This is particularly convenient if you want to compile KDE software with Qt6 quickly.

Likewise, you should install the required dependencies from inside the distrobox rather than from your system's repositories. Then you can start compiling as usual.

After compiling your program with kdesrc-build from inside the distrobox, you can run it with kdesrc-build run, and despite it originating from inside a container and using the libraries from the container, it will run just fine as a GUI application on your system!

The only few gotchas to using this method are:

• You cannot use a full Plasma Desktop session made from git.
• You will need qqc2-desktop-style and Breeze to show the correct theme for your applications.
• You will need the QtWayland library and its respective development package to run your applications natively on a Wayland session.

Other operating systems

Kubuntu 23.10

The default configuration of kdesrc-build requires Qt version 6.6. Kubuntu 23.10 has Qt version 6.4.2. It is recommended that you build Qt in Kubuntu or use a Linux OS that is better supported by kdesrc-build.

FreeBSD

Install the latest release of FreeBSD with KDE Plasma Desktop on your hardware computer or in a virtual machine.

Your user should be member of the "wheel" user group (e.g. this can be configured in the FreeBSD installer, when creating your user you can select additional user groups for your user). Your user should be able to use sudo:

pkg install sudo
visudo
# Uncomment the line: %wheel ALL=(ALL:ALL) ALL

Then set up kdesrc-build using the same procedure as when installing kdesrc-build on a Linux operating system. FreeBSD is currently supported by kdesrc-build. See https://www.youtube.com/watch?v=8MqBnb3Y9JU

Microsoft Windows

You can build and develop KDE projects using the Microsoft Windows operating system.

Apple macOS

You can build and develop KDE projects using the Apple macOS operating system.

What to do if CMake configure fails because a build dependency is missing

See https://community.kde.org/Get_Involved/development/Install_the_dependencies .

Project Documentation

• Handbook
• Readme #1
• Readme #2

Developer's documentation can be found in the doc/source-reference in the project repo.

kf6-qt6 vs. kf5-qt5

Many KDE git repositories can build correctly and run correctly using "kdesrc-build kf6-qt6".

The KDE git repositories that can build correctly and run correctly using "kdesrc-build kf6-qt6" have two long lived git branches:

• A long lived git branch that does not contain the deprecated symbols from kf5-qt5, named e.g. "master".
• And another long lived git branch for qt5-kf5, where the deprecated symbols still exist.

What is "kf6-qt6"? You just set up kdesrc-build following the procedure. The resulting kdesrc-build installation will be of type kf6-qt6. In kdesrc-buildrc in the "global" section you will have "branch-group kf6-qt6". The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch, will use the git branch where the deprecated symbols do not exist e.g. named "master".

What is "kf5-qt5"? Follow the chapter "kdesrc-build Qt5". The resulting kdesrc-build installation will be of type kf5-qt5. In kdesrc-buildrc in the "global" section you will have "branch-group kf5-qt5". The git repositories that have only one long lived git branch e.g. named "master" will use that. The git repositories that have a second long lived git branch where the deprecated symbols still exist e.g. named "kf5" will use that.

Build Qt using kdesrc-build

If you cannot build the KDE frameworks using kdesrc-build and the Qt provided by your Linux distribution is outdated, you might want to build it using kdesrc-build.

In your configuration file use the qt-install-dir option (in the global section) with non-empty value, for example:

global
  qt-install-dir ~/kde6/usr_qt
  branch-group kf6-qt6
end global

Then build it:

kdesrc-build qt6-set

If you want the same for Qt5, change branch-group option and use qt5-set instead of qt6-set.

To compile Qt6 with Qt X11 Extras (which is a necessary library to compile KWindowSystem), you should enable XCB feature during compilation

kdesrc-build qt6-set --cmake-options="-DQT_FEATURE_xcb=ON"

After that, you can build other modules.

Two independent kdesrc-build configurations: kf6-qt6 and kf5-qt5

You can switch between configurations with --rc-file command line option. Generate another config, make the changes for the source-dir, build-dir, install-dir, and other changes you want. Make sure you use different value for persistent-data-file option, to not mix things up.

As an alternative, you can utilize custom variable to make switch from a single config:

global
    _ver 5  # <-- Change this to switch
    source-dir ~/kde${_ver}/src
    build-dir ~/kde${_ver}/build
    install-dir ~/kde${_ver}/usr
    persistent-data-file ~/kde${_ver}/persistent-options.json
end global

include ~/.local/share/kdesrc-build/data/build-include/kf${_ver}-qt${_ver}.ksb

Other CPU architectures than x86_64/amd64 and x86

You can build and develop KDE projects using a Linux OS installed on an ARM architecture CPU.

kdesrc-build issues

See https://community.kde.org/Get_Involved/development/Install_the_dependencies

wayland-protocols is too old, e.g. "kdesrc-build kidletime" fails

mkdir -p ~/kde/misc && cd ~/kde/misc
wget https://gitlab.freedesktop.org/wayland/wayland-protocols/-/releases/1.31/downloads/wayland-protocols-1.31.tar.xz
tar -xJvf wayland-protocols-*.tar.xz && mv wayland-protocols-*/ wayland-protocols
cd wayland-protocols
meson setup builddir --prefix $HOME/kde/usr
meson compile -C builddir
meson install -C builddir

"kdesrc-build kpat" fails because of black-hole-solitaire

This happens on Debian/Ubuntu/Kubuntu. Because there is no Linux distribution binary package for https://github.com/shlomif/black-hole-solitaire.

Solution: append at the end of kdesrc-buildrc file:

options kpat
    cmake-options -DWITH_BH_SOLVER=OFF
end options

libdisplay-info is not available

If your Linux OS does not have a package for libdisplay-info. Append at the end of the file kdesrc-buildrc:

module libdisplay-info
  repository https://gitlab.freedesktop.org/emersion/libdisplay-info.git
end module

Building applications against Qt5 after discontinued support

With this commit, for some applications the support of building against Qt5 was intentionally disabled.

If for some reason you still want to build a Qt5 version of application, you can do it with some hacks. For example, lets say we want Ark. We need to manually see its dependencies listed in metadata:

$ ~/.local/state/sysadmin-repo-metadata/dependencies/dependency-data-kf5-qt5 | grep kde/kdeutils/ark

Then for each dependency, find out the branch that is used for qt5.

Then create a custom ksb file with custom module-set:

~/ark-qt5.ksb

module-set ark-qt5
    repository kde-projects
    use-modules \
        extra-cmake-modules \
        karchive \
        kconfig \
        kcoreaddons \
        kcrash \
        kdbusaddons \
        kdoctools \
        ki18n \
        kiconthemes \
        kio \
        kparts \
        kpty \
        kservice \
        kwidgetsaddons \
        kwindowsystem \
        ark
end module-set


options extra-cmake-modules
    branch kf5
end options

options karchive
    branch kf5
end options

options kconfig
    branch kf5
end options

options kcoreaddons
    branch kf5
end options

options kcrash
    branch kf5
end options

options kdbusaddons
    branch kf5
end options

options kdoctools
    branch kf5
end options

options ki18n
    branch kf5
end options

options kiconthemes
    branch kf5
end options

options kio
    branch kf5
end options

options kparts
    branch kf5
end options

options kpty
    branch kf5
end options

options kservice
    branch kf5
end options

options kwidgetsaddons
    branch kf5
end options

options kwindowsystem
    branch kf5
end options

options ark
    branch release/23.08
end options

# --

# dependency of extra-cmake-modules
options polkit-qt-1
    branch qt5
end options

# dependency of kcoreaddons
options plasma-wayland-protocols
    branch master
end options

# dependency of karchive
options qca
    branch qt5
end options

After that, include it in your main config:

global
    _ver 5
    _build_with_qt6 OFF
    branch-group kf${_ver}-qt${_ver}
    cmake-options -DCMAKE_BUILD_TYPE=Debug -DQT_MAJOR_VERSION=${_ver} -DBUILD_WITH_QT6=${_build_with_qt6}
end global

include ~/Development/kdesrc-build/data/build-include/kf${_ver}-qt${_ver}.ksb
include ~/ark-qt5.ksb

Then edit the metadata file:

~/.local/state/sysadmin-repo-metadata/dependencies/logical-module-structure.json

...
        "kde/*" : {
            "kf6-qt6": "master",
            "kf5-qt5": "master",  // <-- it was empty string, place "master" here
            "stable-kf6-qt6": "release/24.02",
            "stable-kf5-qt5": ""
        },
...

Now you are able to build Ark with qt5:

$ kdesrc-build ark-qt5 --list-build

Fetching remote changes to sysadmin-repo-metadata
Merging sysadmin-repo-metadata changes from branch master
        * You had local changes to sysadmin-repo-metadata, which have been re-applied.
...
 ── ark : release/23.08