Development/Tutorials/Using KXmlGuiWindow/KDE4

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.

The source code on this page applies only to KDE Development Platform 4 ("KDE 4"). For the KDE Frameworks 5 ("KF5") version, see Development/Tutorials/Using_KXmlGuiWindow

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). 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>
#include <KTextEdit>

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

#endif

First we Subclass KXmlGuiWindow on line 7 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 KDE niceties like cursor auto-hiding.

mainwindow.cpp

#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 5, we initialise our text editor with an object. Then on line 6 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 <KApplication>
#include <KAboutData>
#include <KCmdLineArgs>
#include <KLocale>

#include "mainwindow.h"

int main (int argc, char *argv[])
{
  KAboutData aboutData( "tutorial2", 0,
      ki18n("Tutorial 2"), "1.0",
      ki18n("A simple text area"),
      KAboutData::License_GPL,
      ki18n("Copyright (c) 2007 Developer") );
  KCmdLineArgs::init( argc, argv, &aboutData );
  
  KApplication app;
 
  MainWindow* window = new MainWindow();
  window->show();

  return app.exec();
}

The only new lines here (compared to Tutorial 1) are 6, 19 and 20. On line 19, we create our MainWindow object and then on line 20, we display it.

CMake

The best way to build the program is to use CMake. All that's changed since tutorial 1 is that mainwindow.cpp has been added to the sources list and any tutorial1 has become tutorial2.

CMakeLists.txt

project (tutorial2)

find_package(KDE4 REQUIRED)
include_directories(${KDE4_INCLUDES})

set(tutorial2_SRCS 
  main.cpp
  mainwindow.cpp
)

kde4_add_executable(tutorial2 ${tutorial2_SRCS})
target_link_libraries(tutorial2 ${KDE4_KDEUI_LIBS})

Compile and run

To compile, link and run it, make sure you have set up a correct build environment and issue:

cmake . && make && ./tutorial2

Moving On

Now you can move on to using KActions.