Development/Tutorials/Using KXmlGuiWindow/KF5

How To Use KXmlGuiWindow

Tutorial Series	Beginner Tutorial
Previous	Tutorial 1 - Hello World
What's Next	Tutorial 3 - KActions and XMLGUI
Further Reading	KXmlGuiWindow

Abstract

This tutorial carries on from First Program Tutorial and will introduce the KXmlGuiWindow class.

In the previous tutorial, the program caused a dialog box to pop up but we're going to take steps towards a functioning application.

KXmlGuiWindow

KXmlGuiWindow provides a full main window view with menubars, toolbars, a statusbar and a main area in the centre for a large widget. For example the help-menu is predefined. Most KDE applications will derive from this class as it provides an easy way to define menu and toolbar layouts through XML files (this technology is called XMLGUI and is part of the KF5::XmlGui framework). While we will not be using XMLGUI in this tutorial, we will use it in the next.

In order to have a useful KXmlGuiWindow, we must subclass it. So we create two files, a mainwindow.cpp and a mainwindow.h which will contain our code.

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <KXmlGuiWindow>

class KTextEdit;
 
class MainWindow : public KXmlGuiWindow
{
  public:
    MainWindow(QWidget *parent=0);
 
  private:
    KTextEdit* textArea;
};
 
#endif

First we Subclass KXmlGuiWindow on line 8 with class MainWindow : public KXmlGuiWindow.

Then we declare the constructor with MainWindow(QWidget *parent=0);.

And finally we declare a pointer to the object that will make up the bulk of our program. KTextEdit is a generic richtext editor with some niceties like cursor auto-hiding.

mainwindow.cpp

#include <KTextEdit>

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent) : KXmlGuiWindow(parent)
{
  textArea = new KTextEdit();
  setCentralWidget(textArea);
  setupGUI();
}

First, of course, on line 1 we have to include the header file containing the class declaration.

On line 7 we initialise our text editor with an object. Then on line 8 we use KXmlGuiWindow's built-in setCentralWidget() function which tells the KXmlGuiWindow what should appear in the central section of the window.

Finally, KXmlGuiWindow::setupGUI() is called which does a lot of behind-the-scenes stuff and creates the default menu bars (Settings, Help).

Back to main.cpp

In order to actually run this window, we need to add a few lines in main.cpp:

main.cpp

#include <cstdlib>
 
#include <QApplication>
#include <QCommandLineParser>

#include <KAboutData>
#include <KLocalizedString>

#include "mainwindow.h"
 
int main (int argc, char *argv[])
{
    QApplication app(argc, argv);
    KLocalizedString::setApplicationDomain("tutorial2");
    
    KAboutData aboutData(
                         // The program name used internally. (componentName)
                         QStringLiteral("tutorial2"),
                         // A displayable program name string. (displayName)
                         i18n("Tutorial 2"),
                         // The program version string. (version)
                         QStringLiteral("1.0"),
                         // Short description of what the app does. (shortDescription)
                         i18n("A simple text area"),
                         // The license this code is released under
                         KAboutLicense::GPL,
                         // Copyright Statement (copyrightStatement = QString())
                         i18n("(c) 2015"),
                         // Optional text shown in the About box.
                         // Can contain any information desired. (otherText)
                         i18n("Some text..."),
                         // The program homepage string. (homePageAddress = QString())
                         QStringLiteral("http://example.com/"),
                         // The bug report email address
                         // (bugsEmailAddress = QLatin1String("[email protected]")
                         QStringLiteral("[email protected]"));
    
    aboutData.addAuthor(i18n("Name"), i18n("Task"), QStringLiteral("[email protected]"),
                         QStringLiteral("http://your.website.com"), QStringLiteral("OSC Username"));
    KAboutData::setApplicationData(aboutData);
 
    QCommandLineParser parser;
    parser.addHelpOption();
    parser.addVersionOption();
    aboutData.setupCommandLine(&parser);
    parser.process(app);
    aboutData.processCommandLine(&parser);
    
    MainWindow* window = new MainWindow();
    window->show();
    
    return app.exec();
}

The only new lines here (compared to Tutorial 1) are 9, 49 and 50. On line 49, we create our MainWindow object and then on line 50, we display it.

CMake

Add KXmlGui and KTextWidgets frameworks.

CMakeLists.txt

project (tutorial2)

#1
cmake_minimum_required(VERSION 2.8.12 FATAL_ERROR)
set(QT_MIN_VERSION "5.3.0")
set(KF5_MIN_VERSION "5.2.0")

#2
find_package(ECM 1.0.0 REQUIRED NO_MODULE)
set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)

include(KDEInstallDirs)
include(KDECMakeSettings)
include(KDECompilerSettings)
include(FeatureSummary)

# Find Qt modules
find_package(Qt5 ${QT_MIN_VERSION} CONFIG REQUIRED COMPONENTS 
    Core    # QCommandLineParser, QStringLiteral
    Widgets # QApplication 
)

# Find KDE modules
find_package(KF5 ${KF5_MIN_VERSION} REQUIRED COMPONENTS
    CoreAddons      # KAboutData
    I18n            # KLocalizedString
    XmlGui          # KXmlGuiWindow
    TextWidgets     # KTextEdit
)
    

feature_summary(WHAT ALL INCLUDE_QUIET_PACKAGES FATAL_ON_MISSING_REQUIRED_PACKAGES)
    
set(tutorial2_SRCS main.cpp mainwindow.cpp)

# just plain add_executable
add_executable(tutorial2 ${tutorial2_SRCS})

# module-based linking
target_link_libraries(tutorial2
    Qt5::Widgets
    KF5::CoreAddons
    KF5::I18n
    KF5::XmlGui
    KF5::TextWidgets
)

install(TARGETS tutorial2  ${INSTALL_TARGETS_DEFAULT_ARGS})

Notes

1. KF5 Cookbook https://books.kde.org/frameworks5/KDE-Frameworks-Cookbook.html#adding-threadweaver-to-a-project---an-introduction-to-the-frameworks-5-build-system
2. https://community.kde.org/Frameworks/Porting_Notes#Build_System

TODO

warning: ‘virtual void KMainWindow::showAboutApplication()’ is deprecated [-Wdeprecated-declarations] /usr/include/KF5/KXmlGui/kmainwindow.h:604:37: note: declared here

    virtual KXMLGUI_DEPRECATED void showAboutApplication() {}