Widgets Tutorial

Introduction

Widgets are the basic building blocks for graphical user interface (GUI) applications built with Qt. Each GUI component (e.g. buttons, labels, text editor) is a widget that is placed somewhere within a user interface window, or is displayed as an independent window. Each type of widge is provided by a subclass of QWidget, which is itself a subclass of QObject.

QWidget is not an abstract class. It can be used as a container for other widgets, and it can be subclassed with minimal effort to create new, custom widgets. QWidget is often used to create a window inside which other QWidgets are placed.

As with QObjects, QWidgets can be created with parent objects to indicate ownership, ensuring that objects are deleted when they are no longer used. With widgets, these parent-child relationships have an additional meaning: Each child widget is displayed within the screen area occupied by its parent widget. This means that when you delete a window widget, all the child widgets it contains are also deleted.

 #include <QtGui>

 // Include header files for application components.
 // ...

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

     // Set up and show widgets.
     // ...

     return app.exec();
 }