Development/Tutorials/Using KXmlGuiWindow

How To Use KMainWindow

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

Abstract

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

Using KMainWindow

In order to have a useful KMainWindow, we must sub class it. So we create two files, a MainWindow.cpp and a MainWindow.h which will contain our code.

MainWindow.h

1. ifndef MAINWINDOW_H
2. define MAINWINDOW_H

1. include <KMainWindow>
2. include <KTextEdit>

class MainWindow : public KMainWindow {

 public:
   MainWindow(QWidget *parent=0);

 private:
   KTextEdit* textArea;

};

1. endif

First we Subclass KMainWindow on line 7 with with class MainWindow : public KMainWindow.

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

1. include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent) : KMainWindow(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 the built-in setCentralWidget() function which tells the KMainWindow what should appear in the central section of the window.

Finally, KMainWindow::setupGUI() is called which does a lot of behind the scene's 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

1. include <KApplication>
2. include <KAboutData>
3. include <KCmdLineArgs>

1. include "mainwindow.h"

int main (int argc, char *argv[]) {

 KAboutData aboutData( "tutorial2", 
     "Tutorial2", "1.0", "A simple text area",
     KAboutData::License_GPL, "(c) 2006" );
 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 16 and 17. On line 16, we create our MainWindow object and then on line 17, 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})

Moving On

Now you can move on to using KActions.