Setting up and getting started

Getting ready to create our first Kirigami application

Installing Kirigami

Before getting started, we will need to install Kirigami on our machine. There are three ways to do so:

Installing Kirigami from the repositories in your Linux distribution

We need a C++ compiler, Qt development packages, and Kirigami. Open a terminal application and run one of the following, depending on which Linux distribution you are using:

KubuntuKDE Neon
sudo apt install build-essential cmake extra-cmake-modules qtbase5-dev qtdeclarative5-dev qtquickcontrols2-5-dev kirigami2-dev libkf5i18n-dev gettext libkf5coreaddons-dev qml-module-org-kde-qqc2desktopstyle
ManjaroArch
sudo pacman -S base-devel extra-cmake-modules cmake qt5-base qt5-declarative qt5-quickcontrols2 kirigami2 ki18n kcoreaddons breeze qqc2-desktop-style
OpenSUSE
sudo zypper install --type pattern devel_C_C++
sudo zypper install cmake extra-cmake-modules libQt5Core-devel libqt5-qtdeclarative-devel libQt5QuickControls2-devel kirigami2-devel ki18n-devel kcoreaddons-devel qqc2-desktop-style
Fedora
sudo dnf groupinstall "Development Tools" "Development Libraries"
sudo dnf install cmake extra-cmake-modules qt5-qtbase-devel qt5-qtdeclarative-devel qt5-qtquickcontrols2-devel kf5-kirigami2-devel kf5-ki18n-devel kf5-kcoreaddons-devel qqc2-desktop-style

Further information for other distributions can be found here.

If you wish to build Kirigami with Qt6, this is currently not possible with only distribution packages on Linux. You will need to resort to kdesrc-build instead.

Building Kirigami with kdesrc-build

KDE has a custom tool to easily build all of its libraries and programs: kdesrc-build. It can be used to build Kirigami on Linux and FreeBSD.

For this tutorial, you will need to follow the setup instructions for kdesrc-build but using a ~/kde5 directory instead, then copy the sample KF5 file to your home:

cp ~/kde5/src/kdesrc-build/kdesrc-buildrc-kf5-sample ~/.config/kdesrc-buildrc

After that, you may simply run the following on a terminal:

kdesrc-build kirigami kcoreaddons ki18n breeze plasma-integration qqc2-desktop-style
source ~/kde5/build/kirigami/prefix.sh

And then you may compile your Kirigami projects on the same terminal shell you used to source the prefix file. If you close your terminal, you can simply source the file again to compile your app.

Installing Kirigami with Craft

KDE has a custom tool to easily install most of its libraries and programs: Craft. It can be used to install Kirigami on Linux, FreeBSD, Windows, Android and macOS.

You will need to follow the setup instructions for Craft. By the end of the setup, you should have run an environment setup file (craftenv.ps1 or craftenv.sh), which will give you a terminal shell where you will be compiling your Kirigami application.

After that, you may simply run the following on a terminal:

craft kirigami kcoreaddons ki18n breeze kiconthemes qqc2-desktop-style

If you close your terminal, you can simply run the environment setup file again to compile your app.

Project structure

While there are tools that can easily set up our files, we are going to create them manually. This will let us better understand the pieces that are going to make up our new application.

First we create our project folder. We are going to call ours "helloworld".

helloworld/
├── CMakeLists.txt
└── src/
    ├── CMakeLists.txt
    ├── main.cpp
    ├── resources.qrc
    └── contents/
        └── ui/
            └── main.qml

Within this folder we are going to create a src/ folder and CMakeLists.txt. It is generally considered good practice to place all our main code files in a src/ folder. Our src/ folder in turn will contain a folder named contents/, which itself contains a folder called ui/. Here is where we will create our QML files.

This is a KDE convention, but not all KDE projects use this structure. You are free to set things up differently, but you will have to take this into account when creating your CMakeLists.txt and resources.qrc files.

main.qml

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// Includes relevant modules used by the QML
import QtQuick 2.15
import QtQuick.Controls 2.15 as Controls
import QtQuick.Layouts 1.15
import org.kde.kirigami 2.20 as Kirigami

// Provides basic features needed for all kirigami applications
Kirigami.ApplicationWindow {
    // Unique identifier to reference this object
    id: root

    // Window title
    // i18nc() makes a string translatable
    // and provides additional context for the translators
    title: i18nc("@title:window", "Hello World")

    // Set the first page that will be loaded when the app opens
    // This can also be set to an id of a Kirigami.Page
    pageStack.initialPage: Kirigami.Page {
        Controls.Label {
            // Center label horizontally and vertically within parent object
            anchors.centerIn: parent
            text: i18n("Hello World!")
        }
    }
}

Here's where we will be handling our application's frontend.

If you know some Javascript, then much of QML will seem familiar to you (though it does have its own peculiarities). Qt's documentation has an extensive amount of material on this language if you feel like trying something on your own. Over the course of these tutorials we will be focusing much of our attention on our QML code, where we can use Kirigami to get the most out of it.

For now, let's focus on main.qml. First we import a number of important modules:

  • QtQuick, the standard library used in QML applications.
  • QtQuick Controls, which provides a number of standard controls we can use to make our applications interactive.
  • QtQuick Layouts, which provides tools for placing components within the application window.
  • Kirigami , which provides a number of components suited for creating applications that work across devices of different shapes and sizes.

We then come to our base element, Kirigami.ApplicationWindow , which provides some basic features needed for all Kirigami applications. This is the window that will contain each of our pages, the main sections of our UI.

We then set the window's id property to "root". IDs are useful because they let us uniquely reference a component, even if we have several of the same type.

We also set the window title property to "Hello World". You'll notice that we have wrapped our "Hello World" string in a function called i18nc(), where we detail the context of the string as well as the string itself.

We then set the first page of our page stack. Most Kirigami applications are organised as a stack of pages, each page containing related components suited to a specific task. For now, we are keeping it simple, and sticking to a single page. pageStack is an initially empty stack of pages provided by Kirigami.ApplicationWindow , and with pageStack.initialPage: Kirigami.Page {...} we set the first page presented upon loading the application to a Kirigami.Page . This page will contain all our content.

Finally, we include in our page a Controls.Label that lets us place text on our page. We use anchors.centerIn: parent to center our label horizontally and vertically within our parent element. In this case, the parent component of our label is Kirigami.Page . The last thing we need to do is set its text: text: i18n("Hello World!").

main.cpp

main.cpp handles the "business logic" of our application. C++ is handy because it is flexible and fast, even if it is more involved than other programming languages.

main.cpp is also the entrypoint to our application. The two parts of our project, the backend and the user interface, are both set up and started here.

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#include <QApplication>
#include <QQmlApplicationEngine>
#include <QtQml>
#include <QUrl>
#include <QQuickStyle>
#include <KLocalizedContext>
#include <KLocalizedString>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    KLocalizedString::setApplicationDomain("helloworld");
    QCoreApplication::setOrganizationName(QStringLiteral("KDE"));
    QCoreApplication::setOrganizationDomain(QStringLiteral("kde.org"));
    QCoreApplication::setApplicationName(QStringLiteral("Hello World"));

    if (qEnvironmentVariableIsEmpty("QT_QUICK_CONTROLS_STYLE")) {
        QQuickStyle::setStyle(QStringLiteral("org.kde.desktop"));
    }

    QQmlApplicationEngine engine;

    engine.rootContext()->setContextObject(new KLocalizedContext(&engine));
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    if (engine.rootObjects().isEmpty()) {
        return -1;
    }

    return app.exec();
}

For now, we don't need to go into too much detail regarding what our main.cpp code does, but its role will grow significantly more important once we decide to add more complex functionality to our application in the future. If you want to get ahead, you can read more about how this main.cpp works in this page.

resources.qrc

Our resources.qrc is a Qt Resource file. It contains the list of all QML files as well as other files (like custom icons) that will be included in the binary.

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<RCC>
    <qresource prefix="/">
        <file alias="main.qml">contents/ui/main.qml</file>
    </qresource>
</RCC>

Notice the line <file alias="main.qml">contents/ui/main.qml</file>. It details which QML files are going to be included in the compilation process. In our case we are only using main.qml, but if we were to add more QML files to our code, we'd need to make sure we include it in resources.qrc file by adding another line like this one.

This resource file lets us use the "qrc:" + "/main.qml" path in our main.cpp, instead of needing to specify the whole "contents/ui/main.qml" path.

CMakeLists.txt

CMakeLists.txt files are needed to use KDE's build system of choice, CMake. The CMakeLists.txt file in our top-level folder is going to specify some of our application's characteristics. It also includes some of the dependencies we need in order to compile our project.

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cmake_minimum_required(VERSION 3.16)
project(helloworld)

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

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

find_package(Qt${QT_MAJOR_VERSION} REQUIRED NO_MODULE COMPONENTS
    Core
    Quick
    Test
    Gui
    QuickControls2
    Widgets
)

find_package(KF${QT_MAJOR_VERSION} REQUIRED COMPONENTS
    Kirigami2
    I18n
    CoreAddons
)

add_subdirectory(src)

feature_summary(WHAT ALL INCLUDE_QUIET_PACKAGES FATAL_ON_MISSING_REQUIRED_PACKAGES)

The CMakeLists.txt defines how to build your projects. Most of the content here is just to bootstrap your project. You can read a line-by-line, in-depth explanation of what this CMakeLists file does here.

The most important thing to keep in mind is that the Qt and KDE Frameworks dependencies are managed with find_package(). You will have to modify these lines and include any additional components that you decide to use during the development of your application.

The final line, add_subdirectory(src), points CMake to the helloworld/src/ directory, where our source code is located. Let's delve into the helloworld/src/CMakeLists.txt file in there.

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add_executable(helloworld)

target_sources(helloworld PRIVATE
    main.cpp
    resources.qrc
)

target_link_libraries(helloworld
    Qt${QT_MAJOR_VERSION}::Quick
    Qt${QT_MAJOR_VERSION}::Qml
    Qt${QT_MAJOR_VERSION}::Gui
    Qt${QT_MAJOR_VERSION}::QuickControls2
    Qt${QT_MAJOR_VERSION}::Widgets
    KF${QT_MAJOR_VERSION}::I18n
)

install(TARGETS helloworld ${KDE_INSTALL_TARGETS_DEFAULT_ARGS})

This one's a lot shorter! Let's go through what it does:

Now that CMake has been taken care of, let's look at the files we are going to spend the majority of our time working with.

Compiling and running the application

We are almost at the finish line. The last thing we need to do is build and run our application. Doing so will depend on which platform you are on.

If you are running your project on Linux, you will need to specify the place where the program will be installed. To do that, we need to change directories to our helloworld/ folder in our terminal application of choice and run the following commands:

cmake -B build/ -DCMAKE_INSTALL_PREFIX="~/kde5/usr"
cmake --build build/
cmake --install build/

The program will be installed to ~/kde5/usr/bin.

If you are compiling your project with Craft on Windows, you might need to specify a CMake Generator for the first step, depending on whether you are using Visual Studio 2019 (msvc) or MinGW (make) to compile your projects.

If Visual Studio:

cmake -B build/ -G "Visual Studio 16 2019"`
cmake --build build/
cmake --install build/

If MinGW:

cmake -B build/ -G "MinGW Makefiles"
cmake --build build/
cmake --install build/

In both cases, the program will be installed to C:\CraftRoot\bin.

You can then run the helloworld program with:

helloworld # On Linux
helloworld.exe # On Windows

Voilà! Now you will see your very first Kirigami app appear before your very own eyes.

Screenshot of the generated Kirigami application