(Add important notes about kdesrc-build)
(Submit a patch: patch -> Merge Request)
 
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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.
 
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.
  
{{Info|While any operating system can be used to patch or develop KDE software, it's easiest if you use a Linux distribution that provides relatively recent versions of Qt and KDE Frameworks, such as KDE Neon, openSUSE Tumbleweed, Arch/Antergos/Manjaro, Fedora, or non-LTS versions of Ubuntu.<br /><br />Support for distros that ship older software (such as Debian, Ubuntu/Kubuntu 18.04, and openSUSE Leap 15) is still experimental and you may have a better experience developing with [https://neon.kde.org/download KDE Neon Developer Edition] in a virtual machine.}}
+
{{Info|While any operating system can be used to patch or develop KDE software, it's easiest if you use a Linux distribution that provides relatively recent versions of Qt and KDE Frameworks, such as Arch/Manjaro, Fedora, KDE Neon, openSUSE Tumbleweed, or non-LTS versions of Kubuntu.<br /><br />Support for Windows, macOS, and Linux distros that ship older software (such as Debian, Ubuntu/Kubuntu 18.04, and openSUSE Leap 15) is still experimental, and you may have a better experience [[Get Involved/development/Developing in a virtual machine|doing your development in a virtual machine]] when using one of the distributions mentioned above.}}
 
 
 
 
  
 
== New to C++/Qt software development? ==
 
== New to C++/Qt software development? ==
 
Most KDE software is written in C++ using the [https://www.qt.io Qt toolkit] and [[Frameworks | KDE Frameworks]]. Though prior experience with these technologies or other programming languages is helpful, you don't need to be a C++ programmer to get started! For example, no programming knowledge whatsoever is required to do things like improve text labels.
 
Most KDE software is written in C++ using the [https://www.qt.io Qt toolkit] and [[Frameworks | KDE Frameworks]]. Though prior experience with these technologies or other programming languages is helpful, you don't need to be a C++ programmer to get started! For example, no programming knowledge whatsoever is required to do things like improve text labels.
  
{{Note|The Qt wiki contains [https://wiki.qt.io/Books a list of online books] for learning Qt programming. Qt also provides [http://doc.qt.io/qt-5/qtexamplesandtutorials.html lots of examples] you can look at. Information about KDE Frameworks can be found on the [https://techbase.kde.org TechBase wiki], and a [[Books | book]] is available.}}
+
If you'd like to dive deeper, the Qt wiki contains [https://wiki.qt.io/Books a list of online books] for learning Qt programming. Qt also provides [https://doc.qt.io/qt-5/qtexamplesandtutorials.html lots of examples] you can look at. Information about KDE Frameworks can be found on the [https://techbase.kde.org TechBase wiki], and a [[Books | book]] is available.
 
 
 
 
  
 
== One-time setup: your development environment ==
 
== One-time setup: your development environment ==
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{{Note|'''Everything in this section only needs to be done once.''' Once you've done it, your development environment is set up and you can use it to submit patches and develop KDE Software!}}
 
{{Note|'''Everything in this section only needs to be done once.''' Once you've done it, your development environment is set up and you can use it to submit patches and develop KDE Software!}}
 
  
 
=== Install basic tools ===
 
=== Install basic tools ===
 
First you will need to use your operating system's package manager to install some basic tools:
 
First you will need to use your operating system's package manager to install some basic tools:
* Arch/Antergos/Manjaro: <code>sudo pacman -S git cmake dialog</code>
+
* Arch/Manjaro: <code>sudo pacman -S git bzr cmake dialog</code>
* Fedora: <code>sudo dnf install git cmake dialog perl</code>
+
* Fedora: <code>sudo dnf install git bzr cmake dialog perl</code>
* KDE Neon/Kubuntu/Ubuntu/Debian: <code>sudo apt install git cmake dialog</code>
+
* KDE Neon/Kubuntu/Ubuntu/Debian: <code>sudo apt install git bzr cmake dialog</code>
* openSUSE Leap & Tumbleweed: <code>sudo zypper install git cmake dialog</code>
+
* openSUSE Leap & Tumbleweed: <code>sudo zypper install git breezy cmake dialog</code>
 
<br />
 
<br />
Some operating systems also require that you turn on the source repositories before you can install build dependencies (more about that later). Do that now, if necessary:
 
* Kubuntu/Ubuntu/Debian: https://askubuntu.com/questions/158871/how-do-i-enable-the-source-code-repositories
 
* openSUSE Leap & Tumbleweed: <code>sudo zypper mr -e $(zypper repos | awk '/source/{print $5}'))</code>
 
 
  
 
=== Configure Git ===
 
=== Configure Git ===
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</nowiki>
 
</nowiki>
 
The email address you specify above must be the same as the email address used for your https://bugs.kde.org account. If they don't match, then the <tt>BUG: </tt> and <tt>FEATURE: </tt> keywords won't work (see [https://techbase.kde.org/Development/Git/Configuration#Basic_Settings this page] for more information).}}
 
The email address you specify above must be the same as the email address used for your https://bugs.kde.org account. If they don't match, then the <tt>BUG: </tt> and <tt>FEATURE: </tt> keywords won't work (see [https://techbase.kde.org/Development/Git/Configuration#Basic_Settings this page] for more information).}}
 
+
<br />
Now we will set up a '''Git prefix''' to make it easier to interact with KDE's remote Git repositories. Use a text editor to open the <tt>~/.gitconfig</tt> file and add the following:
 
 
 
<syntaxhighlight lang="ini">
 
[url "https://anongit.kde.org/"]
 
    insteadOf = kde:
 
 
    pushInsteadOf = kde:
 
</syntaxhighlight>
 
 
 
Then save the file and close it. This essentially tells Git to accept "kde:" in place of "https://anongit.kde.org/", which allows us to check out repositories more easily, as we will soon see.
 
  
 
=== Set up kdesrc-build ===
 
=== Set up kdesrc-build ===
 
Next, we need a method of '''managing dependencies'''. Every software has dependencies: other pieces of software that provide the functionality they rely on. In order to compile any piece of software, its dependencies must be available.
 
Next, we need a method of '''managing dependencies'''. Every software has dependencies: other pieces of software that provide the functionality they rely on. In order to compile any piece of software, its dependencies must be available.
  
Most Linux-based operating systems do not provide development packages that are up-to-date enough for working on KDE software, so we will compile all the KDE dependencies ourselves. To do this, we use a command-line tool called <code>kdesrc-build</code> to download, manage, and build KDE source code repositories. Let's set it up now:
+
Most Linux-based operating systems do not provide development packages that are up-to-date enough for working on KDE software, so we will compile all the KDE dependencies ourselves. To do this, we use a command-line tool called <code>kdesrc-build</code> to download, manage, and build KDE source code repositories. Let's set it up now! First, we create a new directory for all the KDE source code we will be using. We then clone the source code repository that holds <code>kdesrc-build</code> in that directory, so we have a local copy of it on our computer.
  
 
{{Input|1=<nowiki>
 
{{Input|1=<nowiki>
 
mkdir -p ~/kde/src
 
mkdir -p ~/kde/src
 
cd ~/kde/src/
 
cd ~/kde/src/
git clone kde:kdesrc-build
+
git clone https://invent.kde.org/sdk/kdesrc-build.git  && cd kdesrc-build
 
</nowiki>}}
 
</nowiki>}}
  
Notice how we're using the "kde:" prefix in our <code>git clone</code> command!
+
Next, it's time to set up <code>kdesrc-build</code> and pick up the changes it made to your <tt>~/.bashrc</tt> for the current terminal session:
 
 
We want to add <code>kdesrc-build</code> to your system's <tt>$PATH</tt> variable so you can access it from anywhere, not just when you're inside <tt>~/kde/src/kdesrc-build</tt>. Use a text editor to open the <tt>~/.bashrc</tt> file and add <code>export PATH=~/kde/src/kdesrc-build:$PATH</code>.  Then save the file, close it, and run <code>source ~/.bashrc</code> to pick up the changes.
 
  
Next, set up <code>kdesrc-build</code> using its built-in wizard. The default options should be ok, but feel free to customize anything:
 
 
{{Input|1=<nowiki>
 
{{Input|1=<nowiki>
kdesrc-build --initial-setup
+
./kdesrc-build --initial-setup
 +
source ~/.bashrc
 
</nowiki>}}
 
</nowiki>}}
{{Note|Do not quote or escape any file paths entered in the wizard!}}
 
  
This command does two things. First, it tries to install the basic packages for compiling Qt and KDE software on your distro. Second, it creates a the <code>~/.kdesrc-buildrc</code> configuration file. By default, kdesrc-build will build all the dependencies that a program or framework needs, down to Qt. If you don't want this to be the default behavior, edit the configuration file and set <code>include-dependencies</code> to '''false'''.
+
{{Warning|Do not quote or escape any file paths entered in the wizard! And do not run the command <code>kdesrc-build</code> by itself without any arguments because this will build everything, which is probably overkill right now.}}
  
If your Linux distribution provides a recent version of Qt (>= 5.11), you don't need to build Qt yourself, saving you time and disk space. Simply comment out the <code>qtdir</code> and two <code>include</code> lines related to qt5 in that same configuration file.
+
The initial setup tries to install the basic packages for compiling Qt and KDE software on your distro. It also creates a <code>~/.kdesrc-buildrc</code> configuration file.
 +
If you want a more guided setup process for <code>kdesrc-build</code>, run the command <code>kdesrc-build-setup</code> instead. However, unlike <code>--initial-setup</code>, it won't install packages from your distro for compiling programs so you will have to do that yourself.
  
If you want a more guided setup process for kdersc-build, run the command <code<>kdesrc-build-setup</code> instead. However, unlike <code>--initial-setup</code>, it won't install packages from your distro for compiling programs so you will have to do that yourself. Please consult the [https://docs.kde.org/trunk5/en/extragear-utils//kdesrc-build/ kdesrc-build manual] for more information and options in using the tool.
+
Consult the [https://docs.kde.org/trunk5/en/extragear-utils//kdesrc-build/ kdesrc-build manual] for more information and options.
 +
 
 +
=== Set up Qt ===
 +
By default, <code>kdesrc-build</code> will build from source all the dependencies that a program or framework needs, including the Qt toolkit itself, because the <code>include-dependencies</code> option is set as default in the <code>~/.kdesrc-buildrc</code> file.
 +
 
 +
If your Linux distribution provides a recent version of Qt (5.14 or newer), you can save some time and disk space and use that version instead of building your own. To configure <code>kdesrc-build</code> to skip building Qt, open the configuration file <code>~/.kdesrc-buildrc</code> and comment out the line with <code>qtdir</code> and any lines that begin with <code>include</code> and are related to qt5, but do not comment out the line that includes <code>kf5-qt5-build-include</code>.
 +
 
 +
For example, comment/disable (put a <code>#</code> at the start of the line) or delete these lines if you want to use your distro's Qt packages (actual paths may vary):
 +
 
 +
{{Input|1=<nowiki>
 +
qtdir ~/kde/qt5 # Where to find Qt5
 +
include /path/to/kdesrc-build/qt5-build-include
 +
include /path/to/kdesrc-build/custom-qt5-libs-build-include
 +
</nowiki>}}
  
 
=== Download non-KDE dependencies ===
 
=== Download non-KDE dependencies ===
Even though <code>kdesrc-build</code> will take care of the KDE dependencies for you, it does not yet have the ability to install non-KDE dependencies (see https://bugs.kde.org/show_bug.cgi?id=402428), which are typically acquired using your package manager. To install the required non-KDE dependencies, [[Guidelines and HOWTOs/Build from source/Install the dependencies|read this page]] and follow the instructions laid out there.
+
Even though <code>kdesrc-build</code> will take care of the KDE dependencies for you, it does not yet have the ability to install non-KDE dependencies (see https://invent.kde.org/sdk/kdesrc-build/-/issues/9), which are typically acquired using your package manager. To install the required non-KDE dependencies, [[Guidelines and HOWTOs/Build from source/Install the dependencies|read this page]] and follow the instructions laid out there.
  
 
Once that's done, your development environment is set up and ready to build software! Let's take it for a spin.
 
Once that's done, your development environment is set up and ready to build software! Let's take it for a spin.
 
  
 
== Build some software ==
 
== Build some software ==
{{Note|It can take an hour or more to compile a KDE Application, Framework, or Plasma itself for the first time. The reason for this is that <code>kdesrc-build</code> is compiling ''all'' of the KDE dependencies (See https://invent.kde.org/kde/kdesrc-build/issues/17). The next time you want to compile that or any other piece of KDE software, it will be much faster since most of the dependencies will have already been compiled.}}
+
It can take an hour or more to compile a KDE Application, Framework, or Plasma itself for the first time. The reason for this is that <code>kdesrc-build</code> is compiling ''all'' of the KDE dependencies (See https://invent.kde.org/sdk/kdesrc-build/-/issues/17). The next time you want to compile that or any other piece of KDE software, it will be much faster since most of the dependencies will have already been compiled. If you don't want to build all dependencies (e.g., because you are using a rolling release distro that provides recent versions of software), edit the same configuration file and simply set <code>include-dependencies</code> to '''false''' or add the <code>--no-include-dependencies</code> option when running <code>kdesrc-build</code>.
  
 
=== Applications ===
 
=== Applications ===
'''[[KDE Applications]]''' like Dolphin, Okular, Konsole and Gwenview are standalone apps that can be run on multiple platforms, such as Plasma, GNOME, even macOS and Windows! New versions of KDE Applications are [[Schedules/Applications/18.12 Release Schedule|released three times a year]]. Note that the Discover app store (git repo name: <tt>plasma-discover</tt>) and System Settings app (git repo name: <tt>systemsettings</tt>) are distributed alongside Plasma, but they build like apps app using the below instructions. A list of all KDE applications can be found here: https://userbase.kde.org/Applications.
+
'''[[KDE Applications]]''' like Dolphin, Okular, Konsole and Gwenview are standalone apps that can be run on multiple platforms, such as Plasma, GNOME, even macOS and Windows! New versions of KDE Applications are [[Schedules/Applications/18.12 Release Schedule|released three times a year]]. Note that the Discover app store (git repo name: <tt>plasma-discover</tt>) and System Settings app (git repo name: <tt>systemsettings</tt>) are distributed alongside Plasma, but they build like apps using the below instructions. A list of all KDE applications can be found here: https://userbase.kde.org/Applications.
  
 
For example, here is how to build Dolphin, the KDE file manager:
 
For example, here is how to build Dolphin, the KDE file manager:
  
 
{{Input|1=<nowiki>
 
{{Input|1=<nowiki>
kdesrc-build dolphin --include-dependencies
+
kdesrc-build dolphin
 
</nowiki>}}
 
</nowiki>}}
  
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source ~/kde/build/dolphin/prefix.sh
 
source ~/kde/build/dolphin/prefix.sh
 
~/kde/usr/bin/dolphin
 
~/kde/usr/bin/dolphin
 +
</nowiki>}}
 +
 +
Or using <tt>kdesrc-run</tt> wrapper:
 +
{{Input|1=<nowiki>
 +
kdesrc-run dolphin
 
</nowiki>}}
 
</nowiki>}}
  
 
Did it run? If so, then '''congratulations, you just compiled your own version of Dolphin from source code!'''
 
Did it run? If so, then '''congratulations, you just compiled your own version of Dolphin from source code!'''
 
  
 
=== Frameworks ===
 
=== Frameworks ===
'''[[Frameworks|KDE Frameworks]]''' are libraries of tools and features that can be used by any application or Plasma itself. New versions of KDE Frameworks are [[Schedules/Frameworks|released once a month]]. A list of all frameworks can be found here: https://api.kde.org/frameworks/index.html.
+
'''[[Frameworks|KDE Frameworks]]''' are libraries of tools and features that can be used by any application or Plasma itself. New versions of KDE Frameworks are [[Schedules/Frameworks|released once a month]]. A list of all frameworks can be found here: https://api.kde.org/frameworks.
  
 
For example, here is how to build the KIO framework:
 
For example, here is how to build the KIO framework:
  
 
{{Input|1=<nowiki>
 
{{Input|1=<nowiki>
kdesrc-build kio --include-dependencies
+
kdesrc-build kio
 
</nowiki>}}
 
</nowiki>}}
  
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=== Plasma ===
 
=== Plasma ===
'''[[Plasma|KDE Plasma]]''' is the environment in which you can run apps. Plasma is responsible for providing a desktop with wallpaper, app launchers, and widgets; displaying notifications; managing wired and wireless networks; and similar operating-system level tasks. New versions of Plasma are [[Schedules/Plasma 5|released three times a year]].
+
'''[[Plasma|KDE Plasma]]''' is the environment in which you can run apps. Plasma is responsible for providing a desktop with wallpaper, app launchers, and widgets; displaying notifications; managing wired and wireless networks; and similar operating-system level tasks. New versions of Plasma are [[Schedules/Plasma 5|released three times a year]]. Plasma has multiple ''shells'': [https://kde.org/plasma-desktop Plasma Desktop] for desktop, laptop, and 2-in-1 computers, [https://www.plasma-mobile.org/ Plasma Mobile] for mobile phones, Plasma Bigscreen for televisions, and so on. They all share certain common components, such as a window manager, networking stack, basic graphical components, and so on. Here is how to build them:
 +
{{Input|1=<nowiki>
 +
kdesrc-build plasma-workspace plasma-framework plasma-nm plasma-pa plasma-thunderbolt plasma-vault plasma-workspace-wallpapers kdeplasma-addons kwin kscreen sddm-kcm breeze discover print-manager plasma-sdk kaccounts-integration kaccounts-providers kdeconnect-kde plasma-browser-integration xdg-desktop-portal-kde --include-dependencies
 +
</nowiki>}}
 +
 
 +
==== Plasma Desktop ====
 +
To build the plasma Desktop environment and its related apps, also build the following:
 +
{{Input|1=<nowiki>
 +
kdesrc-build plasma-desktop systemsettings ksysguard kinfocenter kmenuedit --include-dependencies
 +
</nowiki>}}
  
Here is how to build the Plasma desktop environment and its window manager, KWin:
+
To run your custom-built Plasma Desktop, first make it accessible from the SDDM login screen by running the following command:
 +
{{Input|1=<nowiki>
 +
~/kde/build/plasma-workspace/login-sessions/install-sessions.sh
 +
</nowiki>}}
  
 +
Alternatively you can run the new version of plasma on top of your existing system for quick testing:
 
{{Input|1=<nowiki>
 
{{Input|1=<nowiki>
kdesrc-build plasma-desktop plasma-workspace plasma-framework kwin  --include-dependencies
+
source ~/kde/build/plasma-desktop/prefix.sh
 +
~/kde/usr/bin/plasmashell --replace
 
</nowiki>}}
 
</nowiki>}}
  
To run your custom-built Plasma, [[Guidelines and HOWTOs/Build from source/Test plasma|follow these instructions]].
+
In order to make DBus and KAuth actions work properly, create a file named <tt>/etc/dbus-1/session-local.conf</tt> and add the following text to it:
 +
 
 +
<busconfig>
 +
    <servicedir>/home/[yourusername]/kde/usr/share/dbus-1/services</servicedir>
 +
    <servicedir>/home/[yourusername]/kde/usr/share/dbus-1/system-services</servicedir>
 +
    <includedir>/home/[yourusername]/kde/usr/share/dbus-1/system.d/</includedir>
 +
</busconfig>
 +
 
 +
Make sure to replace "[yourusername]" with your actual username!
 +
 
 +
After that, you can log out and select your new plasma session in SDDM's session chooser menu (which is located in the bottom-left corner of the screen if you're using the Breeze SDDM theme).
 +
 
 +
==== Plasma Mobile ====
 +
To build the Plasma Mobile environment and its related apps, also build the following:
 +
{{Input|1=<nowiki>
 +
kdesrc-build plasma-nano plasma-phone-components plasma-settings plasma-camera marble koko vvave okular plasma-angelfish plasma-samegame mtp-server kaidan peruse calindori index-fm maui-pix qrca keysmith --include-dependencies
 +
</nowiki>}}
 +
 
 +
You can run your custom-built Plasma Mobile in a phone-sized window within your existing session like so:
 +
 
 +
{{Input|1=<nowiki>
 +
export XDG_RUNTIME_DIR=/tmp/
 +
export QT_QPA_PLATFORM=wayland
 +
export QT_QPA_PLATFORMTHEME=KDE
 +
export QT_WAYLAND_DISABLE_WINDOWDECORATION=1
 +
export XDG_CURRENT_DESKTOP=KDE
 +
export KSCREEN_BACKEND=QScreen
 +
export KDE_FULL_SESSION=1
 +
export KDE_SESSION_VERSION=5
 +
export QT_QUICK_CONTROLS_MOBILE=1
 +
export PLASMA_PLATFORM=phone:handheld
 +
export $(dbus-launch)
 +
dbus-run-session kwin_wayland --width 360 --height 720 --xwayland "plasmashell -p org.kde.plasma.phone"
 +
</nowiki>}}
 +
 
 +
Plasma Mobile can also be run on a mobile device itself. For information on how to do that, see https://docs.plasma-mobile.org/DevGuide.html#plasma-mobile-device-environment.
 +
 
 +
For more information, see https://docs.plasma-mobile.org/DevGuide.html.
 +
 
 +
=== Iterating on a single project ===
 +
When you're working on a project and you want to rebuild it to test your changes, you can save a lot of time by only rebuilding that project, rather than the entire stack. For example if you are working on <tt>plasma-desktop</tt>, you can run <code>kdesrc-build --no-src --no-include-dependencies plasma-desktop</code>.
 +
 
 +
This will rebuild only <tt>plasma-desktop</tt>
  
 
=== How to solve build problems ===
 
=== How to solve build problems ===
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# Try building the failing module again from scratch using <code>kdesrc-build [failing module] --refresh-build</code>
 
# Try building the failing module again from scratch using <code>kdesrc-build [failing module] --refresh-build</code>
# Make sure that you have all the dependencies for the failing module. Go back to the [[#Download non-KDE dependencies]] section and re-install the non-KDE dependencies. If that doesn't fix the problem. Open the log file for the failing module, which <code>kdesrc-build</code> will print the path at the end of its output. Scroll to the bottom of the log file and read the output to see what missing dependency it is complaining about, then find and install the corresponding package using your distro's package manager your distro. If several looks relevant, install them all just to be safe.
+
# Make sure that you have all the dependencies for the failing module. Go back to the [[#Download non-KDE dependencies]] section and re-install the non-KDE dependencies. If that doesn't fix the problem, open the log file for the failing module, which <code>kdesrc-build</code> will print the path at the end of its output. Scroll to the bottom of the log file and read the output to see what missing dependency it is complaining about, then find and install the corresponding package using your distro's package manager your distro. If several looks relevant, install them all just to be safe. When you have the necessary dependencies, you can save time and resume from the failing module by adding <code>--resume-from [the name of the module that failed]</code> to your <code>kdesrc-build</code> command.
# Check the [https://build.kde.org/view/FAILED/ list of currently broken modules] on the KDE build server. If it's broken there, then it's not your fault. :)
+
# Check the [https://build.kde.org/view/Failing/ list of currently broken modules] on the KDE build server. If it's broken there, then it's not your fault. :)
 
# Ask for help in the the [https://webchat.kde.org/#/room/#kde-devel:kde.org #kde-devel] channel on [[Matrix]] or freenode [[Internet Relay Chat | IRC]]. See [[Get Involved/development#Communicate with the team]]
 
# Ask for help in the the [https://webchat.kde.org/#/room/#kde-devel:kde.org #kde-devel] channel on [[Matrix]] or freenode [[Internet Relay Chat | IRC]]. See [[Get Involved/development#Communicate with the team]]
  
Line 174: Line 225:
 
If any test fails, that needs to be investigated and fixed before you can proceed. Once the tests pass, then run the software again to make sure it still behaves properly. If it doesn't, then 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 and all tests pass.
 
If any test fails, that needs to be investigated and fixed before you can proceed. Once the tests pass, then run the software again to make sure it still behaves properly. If it doesn't, then 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 and all tests pass.
  
 +
== Submit a Merge Request ==
 +
Once you're happy with your patch and have verified that it does what you want, it's time to submit your changes for review!
  
 
+
KDE uses [https://invent.kde.org GitLab] for merge request submission and review. [[Infrastructure/GitLab#Submitting_a_merge_request|Learn how to submit a Merge Request with GitLab]].
== Submit a patch ==
 
Once you're happy with your patch and have verified that it does what you want, it's time to '''generate a diff.''' A diff is a textual representation of the differences between original versions of the files you changed, and the new ones you've produced. You can generate a diff by entering the source repository and running <code>git diff</code>, but we recommend using the <code>arc</code> tool, which will generate a diff and submit it for review very quickly and easily! You can learn how to set it up [https://community.kde.org/Infrastructure/Phabricator#Using_Arcanist_to_post_patches here].
 
 
 
KDE uses [https://phabricator.kde.org Phabricator] for patch submission and review. [[Infrastructure/Phabricator|Learn more about how to submit a patch with Phabricator]].
 
  
 
== Communicate with the team ==
 
== Communicate with the team ==
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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.
 
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 ==
 
== Next steps ==
Line 199: Line 246:
 
You may also want to set up a more customized development environment. See [[Guidelines and HOWTOs/Build from source]].
 
You may also want to set up a more customized development environment. See [[Guidelines and HOWTOs/Build from source]].
  
 +
== Errata ==
 +
openSUSE users will need to make the following changes on their systems to support running KDE software built from source:
 +
 +
<ol>
 +
<li>{{Input|1=<nowiki>
 +
sudo ln -s qdbus /usr/bin/qdbus-qt5
 +
</nowiki>}}
 +
This fixes Spectacle global keyboard shortcuts until https://bugs.kde.org/show_bug.cgi?id=413007 is fixed. See also https://bugzilla.opensuse.org/show_bug.cgi?id=1158841</li>
  
 +
<li>{{Input|1=<nowiki>
 +
sudo cp /etc/pam.d/kscreenlocker /etc/pam.d/kde
 +
</nowiki>}}
 +
This fixes the screen locker so that it will accept your password; otherwise you will need to log in via a TTY and use `loginctl unlock-sessions` to get into your GUI session. See also https://bugzilla.opensuse.org/show_bug.cgi?id=1158966</li>
 +
</ol>
  
 
== Best practices & other useful information==
 
== Best practices & other useful information==
Line 206: Line 266:
 
* [[Guidelines and HOWTOs/Code_Checking| Validating code]]
 
* [[Guidelines and HOWTOs/Code_Checking| Validating code]]
 
* [[Guidelines and HOWTOs/API Documentation|Writing API documentation]] (related: https://api.kde.org).
 
* [[Guidelines and HOWTOs/API Documentation|Writing API documentation]] (related: https://api.kde.org).
 +
* [[Guidelines and HOWTOs/Licensing|Correctly state license information]]
 
* [[Guidelines_and_HOWTOs/Wayland_Porting_Notes|Writing Wayland-friendly code]]
 
* [[Guidelines_and_HOWTOs/Wayland_Porting_Notes|Writing Wayland-friendly code]]
 
* [[Frameworks/Porting_Notes|Porting from KDE 4 to Frameworks 5]]
 
* [[Frameworks/Porting_Notes|Porting from KDE 4 to Frameworks 5]]
 
* [[Guidelines_and_HOWTOs/Making_apps_run_uninstalled|Running applications and their unit tests without first installing them]]
 
* [[Guidelines_and_HOWTOs/Making_apps_run_uninstalled|Running applications and their unit tests without first installing them]]
* [https://community.kde.org/Infrastructure/Phabricator#How_to_review_someone_else.27s_patch How to review patches]
+
* [https://community.kde.org/Infrastructure/GitLab#Testing_someone_else.27s_Merge_Request How to review merge requests]

Latest revision as of 18:11, 22 June 2020

Konqui dev close cropped.png

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.

Dialog-information.png
Information
While any operating system can be used to patch or develop KDE software, it's easiest if you use a Linux distribution that provides relatively recent versions of Qt and KDE Frameworks, such as Arch/Manjaro, Fedora, KDE Neon, openSUSE Tumbleweed, or non-LTS versions of Kubuntu.

Support for Windows, macOS, and Linux distros that ship older software (such as Debian, Ubuntu/Kubuntu 18.04, and openSUSE Leap 15) is still experimental, and you may have a better experience doing your development in a virtual machine when using one of the distributions mentioned above.


New to C++/Qt software development?

Most KDE software is written in C++ using the Qt toolkit and KDE Frameworks. Though prior experience with these technologies or other programming languages is helpful, you don't need to be a C++ programmer to get started! For example, no programming knowledge whatsoever is required to do things like improve text labels.

If you'd like to dive deeper, the Qt wiki contains a list of online books for learning Qt programming. Qt also provides lots of examples you can look at. Information about KDE Frameworks can be found on the TechBase wiki, and a book is available.

One-time setup: your development environment

To build software, you need a development environment: a set of tools that allows you to access and edit the source code, compile it into a form that the computer can run, and deploy it to a safe location. We will now go through the process of setting one up. To accomplish these tasks, you will need to enter commands using a terminal program, such as KDE's Konsole (but any terminal program will suffice).

If you're not familiar with the command line interface, you can find a reasonable tutorial here. However advanced command-line skills are not required, and you will learn what you need along the way!

Note
Everything in this section only needs to be done once. Once you've done it, your development environment is set up and you can use it to submit patches and develop KDE Software!


Install basic tools

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

  • Arch/Manjaro: sudo pacman -S git bzr cmake dialog
  • Fedora: sudo dnf install git bzr cmake dialog perl
  • KDE Neon/Kubuntu/Ubuntu/Debian: sudo apt install git bzr cmake dialog
  • openSUSE Leap & Tumbleweed: sudo zypper install git breezy cmake dialog


Configure Git

We need to set your authorship information properly so that any changes you make can be properly attributed to you:

git config --global user.name "Your Name"
git config --global user.email "[email protected]"
Note
The name you provide should be your actual name, not your KDE Identity username.

The email address you specify above must be the same as the email address used for your https://bugs.kde.org account. If they don't match, then the BUG: and FEATURE: keywords won't work (see this page for more information).


Set up kdesrc-build

Next, we need a method of managing dependencies. Every software has dependencies: other pieces of software that provide the functionality they rely on. In order to compile any piece of software, its dependencies must be available.

Most Linux-based operating systems do not provide development packages that are up-to-date enough for working on KDE software, so we will compile all the KDE dependencies ourselves. To do this, we use a command-line tool called kdesrc-build to download, manage, and build KDE source code repositories. Let's set it up now! First, we create a new directory for all the KDE source code we will be using. We then clone the source code repository that holds kdesrc-build in that directory, so we have a local copy of it on our computer.

mkdir -p ~/kde/src
cd ~/kde/src/
git clone https://invent.kde.org/sdk/kdesrc-build.git  && cd kdesrc-build

Next, it's time to set up kdesrc-build and pick up the changes it made to your ~/.bashrc for the current terminal session:

./kdesrc-build --initial-setup
source ~/.bashrc
Warning.png
Warning
Do not quote or escape any file paths entered in the wizard! And do not run the command kdesrc-build by itself without any arguments because this will build everything, which is probably overkill right now.


The initial setup tries to install the basic packages for compiling Qt and KDE software on your distro. It also creates a ~/.kdesrc-buildrc configuration file. If you want a more guided setup process for kdesrc-build, run the command kdesrc-build-setup instead. However, unlike --initial-setup, it won't install packages from your distro for compiling programs so you will have to do that yourself.

Consult the kdesrc-build manual for more information and options.

Set up Qt

By default, kdesrc-build will build from source all the dependencies that a program or framework needs, including the Qt toolkit itself, because the include-dependencies option is set as default in the ~/.kdesrc-buildrc file.

If your Linux distribution provides a recent version of Qt (5.14 or newer), you can save some time and disk space and use that version instead of building your own. To configure kdesrc-build to skip building Qt, open the configuration file ~/.kdesrc-buildrc and comment out the line with qtdir and any lines that begin with include and are related to qt5, but do not comment out the line that includes kf5-qt5-build-include.

For example, comment/disable (put a # at the start of the line) or delete these lines if you want to use your distro's Qt packages (actual paths may vary):

qtdir  ~/kde/qt5 # Where to find Qt5
include /path/to/kdesrc-build/qt5-build-include
include /path/to/kdesrc-build/custom-qt5-libs-build-include

Download non-KDE dependencies

Even though kdesrc-build will take care of the KDE dependencies for you, it does not yet have the ability to install non-KDE dependencies (see https://invent.kde.org/sdk/kdesrc-build/-/issues/9), which are typically acquired using your package manager. To install the required non-KDE dependencies, read this page and follow the instructions laid out there.

Once that's done, your development environment is set up and ready to build software! Let's take it for a spin.

Build some software

It can take an hour or more to compile a KDE Application, Framework, or Plasma itself for the first time. The reason for this is that kdesrc-build is compiling all of the KDE dependencies (See https://invent.kde.org/sdk/kdesrc-build/-/issues/17). The next time you want to compile that or any other piece of KDE software, it will be much faster since most of the dependencies will have already been compiled. If you don't want to build all dependencies (e.g., because you are using a rolling release distro that provides recent versions of software), edit the same configuration file and simply set include-dependencies to false or add the --no-include-dependencies option when running kdesrc-build.

Applications

KDE Applications like Dolphin, Okular, Konsole and Gwenview are standalone apps that can be run on multiple platforms, such as Plasma, GNOME, even macOS and Windows! New versions of KDE Applications are released three times a year. Note that the Discover app store (git repo name: plasma-discover) and System Settings app (git repo name: systemsettings) are distributed alongside Plasma, but they build like apps using the below instructions. A list of all KDE applications can be found here: https://userbase.kde.org/Applications.

For example, here is how to build Dolphin, the KDE file manager:

kdesrc-build dolphin

As a part of this process, Dolphin was installed to ~/kde/usr/bin/dolphin. There is no need to manually install anything; kdesrc-build installed it for you! Source the project's auto-generated prefix.sh file every time you want to run your custom-compiled version of Dolphin:

source ~/kde/build/dolphin/prefix.sh
~/kde/usr/bin/dolphin

Or using kdesrc-run wrapper:

kdesrc-run dolphin

Did it run? If so, then congratulations, you just compiled your own version of Dolphin from source code!

Frameworks

KDE Frameworks are libraries of tools and features that can be used by any application or Plasma itself. New versions of KDE Frameworks are released once a month. A list of all frameworks can be found here: https://api.kde.org/frameworks.

For example, here is how to build the KIO framework:

kdesrc-build kio

Now you can run an existing app using your custom-made version of the framework! For example, the following will run Dolphin, but it will be using the KIO library that you just built:

source ~/kde/build/kio/prefix.sh
~/kde/usr/bin/dolphin

Plasma

KDE Plasma is the environment in which you can run apps. Plasma is responsible for providing a desktop with wallpaper, app launchers, and widgets; displaying notifications; managing wired and wireless networks; and similar operating-system level tasks. New versions of Plasma are released three times a year. Plasma has multiple shells: Plasma Desktop for desktop, laptop, and 2-in-1 computers, Plasma Mobile for mobile phones, Plasma Bigscreen for televisions, and so on. They all share certain common components, such as a window manager, networking stack, basic graphical components, and so on. Here is how to build them:

kdesrc-build plasma-workspace plasma-framework plasma-nm plasma-pa plasma-thunderbolt plasma-vault plasma-workspace-wallpapers kdeplasma-addons kwin kscreen sddm-kcm breeze discover print-manager plasma-sdk kaccounts-integration kaccounts-providers kdeconnect-kde plasma-browser-integration xdg-desktop-portal-kde --include-dependencies

Plasma Desktop

To build the plasma Desktop environment and its related apps, also build the following:

kdesrc-build plasma-desktop systemsettings ksysguard kinfocenter kmenuedit --include-dependencies

To run your custom-built Plasma Desktop, first make it accessible from the SDDM login screen by running the following command:

~/kde/build/plasma-workspace/login-sessions/install-sessions.sh

Alternatively you can run the new version of plasma on top of your existing system for quick testing:

source ~/kde/build/plasma-desktop/prefix.sh
~/kde/usr/bin/plasmashell --replace

In order to make DBus and KAuth actions work properly, create a file named /etc/dbus-1/session-local.conf and add the following text to it:

<busconfig>
    <servicedir>/home/[yourusername]/kde/usr/share/dbus-1/services</servicedir>
    <servicedir>/home/[yourusername]/kde/usr/share/dbus-1/system-services</servicedir>
    <includedir>/home/[yourusername]/kde/usr/share/dbus-1/system.d/</includedir>
</busconfig>

Make sure to replace "[yourusername]" with your actual username!

After that, you can log out and select your new plasma session in SDDM's session chooser menu (which is located in the bottom-left corner of the screen if you're using the Breeze SDDM theme).

Plasma Mobile

To build the Plasma Mobile environment and its related apps, also build the following:

kdesrc-build plasma-nano plasma-phone-components plasma-settings plasma-camera marble koko vvave okular plasma-angelfish plasma-samegame mtp-server kaidan peruse calindori index-fm maui-pix qrca keysmith --include-dependencies

You can run your custom-built Plasma Mobile in a phone-sized window within your existing session like so:

export XDG_RUNTIME_DIR=/tmp/
export QT_QPA_PLATFORM=wayland
export QT_QPA_PLATFORMTHEME=KDE
export QT_WAYLAND_DISABLE_WINDOWDECORATION=1
export XDG_CURRENT_DESKTOP=KDE
export KSCREEN_BACKEND=QScreen
export KDE_FULL_SESSION=1
export KDE_SESSION_VERSION=5
export QT_QUICK_CONTROLS_MOBILE=1
export PLASMA_PLATFORM=phone:handheld
export $(dbus-launch)
dbus-run-session kwin_wayland --width 360 --height 720 --xwayland "plasmashell -p org.kde.plasma.phone"

Plasma Mobile can also be run on a mobile device itself. For information on how to do that, see https://docs.plasma-mobile.org/DevGuide.html#plasma-mobile-device-environment.

For more information, see https://docs.plasma-mobile.org/DevGuide.html.

Iterating on a single project

When you're working on a project and you want to rebuild it to test your changes, you can save a lot of time by only rebuilding that project, rather than the entire stack. For example if you are working on plasma-desktop, you can run kdesrc-build --no-src --no-include-dependencies plasma-desktop.

This will rebuild only plasma-desktop

How to solve build problems

Did one or more modules fail to build (displayed in red font) using kdesrc-build? Here's what to do:

  1. Try building the failing module again from scratch using kdesrc-build [failing module] --refresh-build
  2. Make sure that you have all the dependencies for the failing module. Go back to the #Download non-KDE dependencies section and re-install the non-KDE dependencies. If that doesn't fix the problem, open the log file for the failing module, which kdesrc-build will print the path at the end of its output. Scroll to the bottom of the log file and read the output to see what missing dependency it is complaining about, then find and install the corresponding package using your distro's package manager your distro. If several looks relevant, install them all just to be safe. When you have the necessary dependencies, you can save time and resume from the failing module by adding --resume-from [the name of the module that failed] to your kdesrc-build command.
  3. Check the list of currently broken modules on the KDE build server. If it's broken there, then it's not your fault. :)
  4. Ask for help in the the #kde-devel channel on Matrix or freenode IRC. See Get Involved/development#Communicate with the team

Choose what to do

Now that you can compile and deploy custom versions of KDE software, you can open your editor and start hacking on the source code! The code for the version of Dolphin that you built earlier is located at ~/kde/src/dolphin/; other projects you build with kdesrc-build will live in similar locations.

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 Communicate 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 bugfixes. Start slowly and build trust!

Here are some other ideas for starting points:

  • Improve awkwardly-worded messages and labels that are written in English. This is a great way for non-programmers to contribute! If you can compile software and have a good grasp of English, you can make a big difference here.
  • Work on Junior Jobs, which are small tasks that are suitable for beginners (both bugs and features).
  • Work on Bugs related to KDE's Usability & Productivity initiative, many of which are small and easy.
  • The English Breakfast Network searches out simple, common issues in code that should be fixed, and going through the problems on there can provide a good overview of the code.

Test your changes

Once you've made some changes, make sure the project still compiles and installs, and make sure the changes have the desired effect when you run the software. Then it's time to run the project's unit tests:

cd ~/kde/build/dolphin/
source ./prefix.sh
ctest --output-on-failure

If any test fails, that needs to be investigated and fixed before you can proceed. Once the tests pass, then run the software again to make sure it still behaves properly. If it doesn't, then 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 and all tests pass.

Submit a Merge Request

Once you're happy with your patch and have verified that it does what you want, it's time to submit your changes for review!

KDE uses GitLab for merge request submission and review. Learn how to submit a Merge Request with GitLab.

Communicate with the team

There are several ways to get in touch with KDE developers, either generally or for a specific project. The most important communications channels are:

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 real-time chat channels, 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

Sharpen your skills by going through the KDE development tutorials. And try out KDevelop, the KDE IDE.

After you have had several drama-free 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 customized development environment. See Guidelines and HOWTOs/Build from source.

Errata

openSUSE users will need to make the following changes on their systems to support running KDE software built from source:

  1. sudo ln -s qdbus /usr/bin/qdbus-qt5
    
    This fixes Spectacle global keyboard shortcuts until https://bugs.kde.org/show_bug.cgi?id=413007 is fixed. See also https://bugzilla.opensuse.org/show_bug.cgi?id=1158841
  2. sudo cp /etc/pam.d/kscreenlocker /etc/pam.d/kde
    
    This fixes the screen locker so that it will accept your password; otherwise you will need to log in via a TTY and use `loginctl unlock-sessions` to get into your GUI session. See also https://bugzilla.opensuse.org/show_bug.cgi?id=1158966

Best practices & other useful information


This page was last edited on 22 June 2020, at 18:11. Content is available under Creative Commons License SA 4.0 unless otherwise noted.