Get Involved/development

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< Get Involved
Revision as of 16:42, 28 September 2018 by Frinring (talk | contribs) (Add section about installation before creating a patch (to make sure runtime works before working on patch, also do some test need installation))

By joining the ranks of KDE developers, you will get to implement new features and defeat bugs both daunting and simple, all while collaborating to make coherent and stable releases. Developers collaborate in teams based on what area they are working in. These can be small teams working on a single application, up to large teams working on a group of related pieces of software. Many developers are in more than one team.

KDE runs or participates in several mentoring programs to help new developers, including an informal list of people who are willing to help newcomers get started. See the Mentoring page for more details.


Choosing what to do

A good place to start is with a small bug or feature in an existing piece of software that affects you personally ("scratch your own itch"). Get in touch with the existing developers (see Communicating with the team, below) and they can help you out, by pointing you to the right place in the code and giving advice about how to tackle the problem

Try not to start by proposing or working on major features or significant design changes. These can be controversial, and the smoothest way to get going is by working on relatively non-controversial bug-fixes.

Other ideas for starting points are:

New to (C++/Qt) software development?

Most KDE software is written in C++ using the Qt framework. There are many guides to C++ online, and which one works for you will depend on how you learn best and what previous programming experience you have.

For learning Qt, you can find a list of books for learning Qt on the Qt wiki. Qt also provides lots of examples you can look at.

Most KDE software is also built on other KDE software, particularly the KDE Frameworks. The TechBase wiki has documentation about using these libraries, and a book is available. See also Guidelines and HOWTOs/Development.

Get the code

First you will need to use your distro's package manager to install some basic tools:

  • Arch/Antergos/Manjaro: 
    sudo pacman -S git cmake
  • Debian/Ubuntu/KDE Neon: 
    sudo apt install git cmake
  • Fedora: 
    sudo dnf install git cmake
  • openSUSE: 
    sudo zypper install git cmake

Note

If you are not familiar with the Git source control system, the Git Book is a good introduction, but you will learn what you need here if you're new to git.


Next, create a folder to hold all the source code repositories you're going to be downloading! 

mkdir ~/repos
cd ~/repos

Now download the source code for the project you would like to work on. All the KDE git repositories can be found at https://cgit.kde.org/. Find the official project/repository name of the software you want to work on. Most are identical to the software's name; e.g. the repository name for Okular is okular; the repository name for Breeze Icons is breeze-icons. Once you've identified the correct repository, download it locally: 

git clone git://anongit.kde.org/<repository name>.git

Set up your development environment

First of all, don't worry about this process destabilizing your machine. Your existing software is installed to /usr, and when you produce own patched software, it will be installed to /opt/kde leaving the original software untouched.

In order to compile a piece of KDE software, you will first need to use your distro's package manager to download the dependencies for the project you would like to patch, so that it will compile.

The way to do this varies according to your distro (If you don't see it listed below, it is not a recommended development platform):

Arch/Antergos/Manjaro

sudo pacman -S git <repo/package name>

Fedora

First add the <insert thing here> Copr, which will upgrade your system to use newer KDE software:

Warning

Due to the nature of package dependencies, this will upgrade the entire KDE software stack. Do not proceed unless you are okay with this.
[Insert method of updating KDE packages in Fedora here]

Then install the dependencies for the software you want to work on: 

sudo dnf builddep <repo/package name>

KDE Neon

sudo apt build-dep <repo/package name>

Kubuntu

First add the Kubuntu Backports PPA, which will upgrade your system to use newer KDE software:

Warning

Due to the nature of package dependencies, this will upgrade the entire KDE software stack. Do not proceed unless you are okay with this.
sudo add-apt-repository ppa:kubuntu-ppa/backports
sudo apt update
sudo apt full-upgrade

Then install the dependencies for the software you want to work on: 

sudo apt build-dep <repo/package name>

openSUSE Leap

openSUSE Leap does not ship the latest release of KDE software. As that is recommended or even necessary for development, you need to add extra repositories to get later releases. Read the openSUSE wiki page for instructions.

Warning

Due to the nature of package dependencies, this will upgrade the entire KDE software stack. Do not proceed unless you are okay with this.

Then install the dependencies for the software you want to work on: 

sudo zypper si -d <repo/package name>

openSUSE Tumbleweed

First enable the source repository: 

sudo zypper mr -e repo-source

Then install the dependencies for the software you want to work on: 

sudo zypper si -d <package name>


Compile the software

Before you work on your patch, try to compile the software to make sure that your development environment is set up properly: 

mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=/opt/kde/ ..
make

(Notice how we are telling CMake to install to /opt/kde/ instead of /usr/ (which is the normal location). This is because we don't want to overwrite the software provided by your distro, which could destabilize the system.

Did the project compile? Great! Move onto the next section. If you run into problems, see this page for what to do about it.

Install the software

After compilation, try to also install and run the software to make sure that your development environment is also set up properly for the runtime:

You will call this to install your compiled software: 

sudo make install

This will install the software to /opt/kde/.

Note: If you install into a user controlled directory e.g. ~/build you might have to set DESTDIR environment variable: 

env DESTDIR=~/build make install

To actually run the software, you will need to set some environment variables to account for the non-standard location. First, create a file with the environment variables (this only needs to be done once): 

cat > ~/.kderc << "EOF"
export KF5=/opt/kde
export QTDIR=/usr
export CMAKE_PREFIX_PATH=$KF5:$CMAKE_PREFIX_PATH
export XDG_DATA_DIRS=$KF5/share:$XDG_DATA_DIRS:/usr/share
export XDG_CONFIG_DIRS=$KF5/etc/xdg:$XDG_CONFIG_DIRS:/etc/xdg
export PATH=$KF5/bin:$QTDIR/bin:$PATH
export QT_PLUGIN_PATH=$KF5/lib/plugins:$KF5/lib64/plugins:$KF5/lib/x86_64-linux-gnu/plugins:$QTDIR/plugins:$QT_PLUGIN_PATH
export QML2_IMPORT_PATH=$KF5/lib/qml:$KF5/lib64/qml:$KF5/lib/x86_64-linux-gnu/qml:$QTDIR/qml
export QML_IMPORT_PATH=$QML2_IMPORT_PATH
export KDE_SESSION_VERSION=5
export KDE_FULL_SESSION=true
export SASL_PATH=/usr/lib/sasl2:$KF5/lib/sasl2
EOF

Now source it to pick up the new environment variables: 

source ~/.kderc

Now you're ready to run your installed software! 

/opt/kde/bin/<the program>


Make your patch

Now you can open your editor and get hacking! As before, make sure it compiles: 

make

Test your patch

At this point, you have a patch, and the project still compiles. Now it's time to run the project's unit tests: 

make test

Note that with many software developed in the KDE community the tests might rely on installed resources, so before you might want to also update the installation: 

sudo make install

In that case you also need to make sure you are running the tests in an environment as also created for the program. So if not yet called, do now: 

source ~/.kderc

If any test fails, that needs to be investigated before you can proceed. If the tests pass, then it's time to run the software again, as shown above: 

/opt/kde/bin/<the program>

Does it behave as you expect? Great! If not, go back and work on your patch some more, then re-compile and re-deploy, and test again, until the program does what you'd like it to do.

Submitting your first patch

Once you're happy with your patch and have verified that it does what you want, you need to send it to other KDE developers for review. KDE uses Phabricator for this. Learn how to submit a patch with Phabricator


Communicating with the team

There are several ways to get in touch with KDE developers, and developers for a specific project. The two most important are:

Both of these are general KDE development communication channels, and you may get directed to a more appropriate place for the project you are interested in. There is a list of mailing lists if you want to find a mailing list for a specific team directly. Many teams have their own Telegram rooms, too.

You can also try looking for the team's section on the Main Page of this wiki. Many teams have information there for new contributors.


Next steps

After you have had several patches accepted, a KDE developer is likely to suggest you get a Developer account, which will allow you to commit directly to KDE projects. With very few limits on where you can commit, you will be expected to act responsibly. At this point, congratulations! You are officially a KDE developer!

You may also want to set up a more permanent or advanced development environment, which will be very handy to start working on KDE Frameworks or Plasma itself. See Guidelines and HOWTOs/Build from source

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