Building Task Manager Widget By Itself

I recently was debugging KDE Bug #401579 and wanted to build just the Task Manager QML widget and C++ plugin by itself.

Normally you would need to compile the entire plasma-desktop project, which isn’t a huge hurdle once you’ve gotten the development packages installed. The much more annoying problem is testing. Installing plasma-desktop without rebuilding and installing all the dependencies like plasma-workspace and plasma-frameworks could break your Plasma installation. To properly build it, you’d use the kdesrc-build scripts, but we want to avoid that.

To build it by itself, we just need to edit the applets/taskmanager/CMakeLists.txt so it thinks it’s the “root” CMakeList.txt so we can avoid compiling everything else.

First lets download the plasma-desktop repo.

git clone git://anongit.kde.org/plasma-desktop
cd plasma-desktop

Then we’ll open up applets/taskmanager/CMakeLists.txt and some of the stuff from the missing info which is mostly taken from the CMakeLists.txt in plasma-desktop’s root directory.

cmake_minimum_required(VERSION 3.0)

project(plasma-desktop)

set(PROJECT_VERSION "5.14.80")
set(PROJECT_VERSION_MAJOR 5)

set(QT_MIN_VERSION "5.11.0")
set(KF5_MIN_VERSION "5.50.0")

find_package(ECM ${ECM_MIN_VERSION} REQUIRED NO_MODULE)
set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR} ${CMAKE_MODULE_PATH})

include(KDEInstallDirs)
include(KDECMakeSettings)
include(KDECompilerSettings NO_POLICY_SCOPE)

find_package(Qt5 ${QT_MIN_VERSION} REQUIRED COMPONENTS
    Core
    Gui
    DBus
    Widgets
    Quick
)
find_package(KF5 REQUIRED COMPONENTS
    CoreAddons
    Declarative
    DocTools
    GlobalAccel
    I18n
    Plasma
    KIO
    Activities
    ActivitiesStats
)

Next we can try compiling just the applets/taskmanager folder. We create a new “build” directory and enter it. Then we run cmake using the source code from the parent directory (applets/taskmanager) using ... cmake will check if all the dependencies mentioned in CMakeLists.txt are installed.

Then we run make which actually compiles your code. If you missed mentioning a dependency using find_package() in the CMakeLists.txt, make might throw an error. Further down in CMakeLists.txt will be a target_link_libraries() function you can use as a reference for populating find_package().

cd applets/taskmanager
mkdir -p build
cd build
cmake .. -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTING=OFF -DKDE_INSTALL_USE_QT_SYS_PATHS=ON
make

If everything compiled correctly, we can install it to test it.

sudo make install

Then in another terminal, run the following to restart plasmashell.

killall plasmashell; kstart5 plasmashell

Now that you’ve setup a test environment, you can start poking around the Task Manager C++ plugin.