How to Use QPushButton
Overview
Using QPushButton developers can create and handle buttons. This class is easy to use and customize so it is among the most useful classes in Qt. In general the button displays text but an icon can also be displayed.
QPushButton inherits QAbstractButton which in turn inherits QWidget.
Signals
Inherited from QAbstractButton
- void clicked ( bool checked = false )
- void pressed ()
- void released ()
- void toggled ( bool checked )
Inherited from QWidget
- void customContextMenuRequested ( const QPoint &pos )
Inherited from QObject
- void destroyed ( QObject * obj = 0 )
Basic Usage
Text
The text of QPushButton can be set upon creation or using setText(). To get the current text of the button use text().
Icon
The icon of QPushButton can also be set upon creation. After creation the icon can be changed using setIcon() To get the current icon of the button use icon()
Set Position and Size
To set the position and the size of the button use setGeometry(). If you want just to modify the size of the button use resize()
Handle Button
QPushButton emits signals if an event occurs. To handle the button connect its appropriate signal to a slot:
connect(m_button, SIGNAL (released()),this, SLOT (handleButton()));
Example
The following simple code snippet shows how to create and use QPushButton. It has been tested on Qt Symbian Simulator.
An instance of QPushButton is created. Signal released() is connected to slot handleButton() which changes the text and the size of the button.
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QtGui/QMainWindow>
#include <QtGui/QPushButton>
//#include <QMainWindow>//For Qt5
//#include <QPushButton>//For Qt5
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
private slots:
void handleButton();
private:
QPushButton *m_button;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include <QtCore/QCoreApplication>
//#include <QCoreApplication>//For Qt5
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
{
// Create the button, make "this" the parent
m_button = new QPushButton("My Button", this);
// set size and location of the button
m_button->setGeometry(QRect(QPoint(100, 100),
QSize(200, 50)));
// Connect button signal to appropriate slot
connect(m_button, SIGNAL (released()), this, SLOT (handleButton()));
}
void MainWindow::handleButton()
{
// change the text
m_button->setText("Example");
// resize button
m_button->resize(100,100);
}
main.cpp
#include "mainwindow.h"
#include <QtGui/QApplication>
//#include <QApplication> //For Qt5
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MainWindow mainWindow;
mainWindow.showMaximized();
return app.exec();
}