Menus and toolbars in Qt4

last modified October 18, 2023

In this part of the Qt4 C++ programming tutorial, we talk about menus and toolbars in Qt4 applications.

A menubar is a common part of a GUI application. It is a group of commands located in various places called menus. Menus group commands that we can use in an application. Toolbars provide a quick access to the most frequently used commands.

Simple menu

The first example shows a simple menu.

simplemenu.h

#pragma once

#include <QMainWindow>
#include <QApplication>

class SimpleMenu : public QMainWindow {

  public:
    SimpleMenu(QWidget *parent = 0);
};

This is a header file for our code example.

simplemenu.cpp

#include "simplemenu.h"
#include <QMenu>
#include <QMenuBar>

SimpleMenu::SimpleMenu(QWidget *parent)
    : QMainWindow(parent) {
    
  QAction *quit = new QAction("&Quit", this);

  QMenu *file;
  file = menuBar()->addMenu("&File");
  file->addAction(quit);

  connect(quit, SIGNAL(triggered()), qApp, SLOT(quit()));
}

We have a menubar, a menu and an action. In order to work with menus, we must inherit from a QMainWindow widget.

QAction *quit = new QAction("&Quit", this);

This code line creates a QAction. Each QMenu has one or more action objects.

QMenu *file;
file = menuBar()->addMenu("&File");

We create a QMenu object.

file->addAction(quit);

We put an action inside the menu using the addAction method.

connect(quit, SIGNAL(triggered()), qApp, SLOT(quit()));

When we select this option from the menu, the application quits.

main.cpp

#include "simplemenu.h"

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

  QApplication app(argc, argv);  
    
  SimpleMenu window;

  window.resize(250, 150);
  window.setWindowTitle("Simple menu");
  window.show();

  return app.exec();
}

The main file.

Icons, shortcuts, and separators

In the following example, we further enhance our previous application. We add icons to the menus, use shortcuts and a separator.

anothermenu.h

#pragma once

#include <QMainWindow>
#include <QApplication>

class AnotherMenu : public QMainWindow {
    
  public:
    AnotherMenu(QWidget *parent = 0);
};

The header file for the example.

anothermenu.cpp

#include "anothermenu.h"
#include <QMenu>
#include <QMenuBar>

AnotherMenu::AnotherMenu(QWidget *parent)
    : QMainWindow(parent) {
          
  QPixmap newpix("new.png");
  QPixmap openpix("open.png");
  QPixmap quitpix("quit.png");

  QAction *newa = new QAction(newpix, "&New", this);
  QAction *open = new QAction(openpix, "&Open", this);
  QAction *quit = new QAction(quitpix, "&Quit", this);
  quit->setShortcut(tr("CTRL+Q"));

  QMenu *file;
  file = menuBar()->addMenu("&File");
  file->addAction(newa);
  file->addAction(open);
  file->addSeparator();
  file->addAction(quit);
  
  qApp->setAttribute(Qt::AA_DontShowIconsInMenus, false);

  connect(quit, SIGNAL(triggered()), qApp, SLOT(quit()));
}

In our example, we have one menu with three actions. Only the quit action will actually do something if we select it. We also create a separator and a CTRL+Q shortcut, which terminates the application.

QPixmap newpix("new.png");
QPixmap openpix("open.png");
QPixmap quitpix("quit.png");

These are images that we use in menus. Note that some desktop environments might not display images in the menus.

QAction *newa = new QAction(newpix, "&New", this);
QAction *open = new QAction(openpix, "&Open", this);
QAction *quit = new QAction(quitpix, "&Quit", this);

In this code we use the QAction constructor with a pixmap as the first argument.

quit->setShortcut(tr("CTRL+Q"));

Here we create a keyboard shortcut. By pressing this shortcut, we will run the quit action which will quit the application.

file->addSeparator();

We create a separator. The separator is a horizontal line which enables us to group menu actions into some logical groups.

qApp->setAttribute(Qt::AA_DontShowIconsInMenus, false);

In some environments, the menu icons are not shown by default. In this case we can disable the Qt::AA_DontShowIconsInMenus attribute.

main.cpp

#include "anothermenu.h"

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

  QApplication app(argc, argv);  
    
  AnotherMenu window;

  window.resize(350, 200);
  window.move(300, 300);  
  window.setWindowTitle("Another menu");
  window.show();

  return app.exec();
}

This is the main file.

Checkable menu

In the next example, we create a checkable menu. This will be an action with a check box. The option toggles the visibility of a statusbar.

checkable.h

#pragma once

#include <QMainWindow>
#include <QApplication>

class Checkable : public QMainWindow {
    
  Q_OBJECT  

  public:
    Checkable(QWidget *parent = 0);
 
  private slots:
    void toggleStatusbar();

  private:
    QAction *viewst;
};

The header file for the example.

checkable.cpp

#include "checkable.h"
#include <QMenu>
#include <QMenuBar>
#include <QStatusBar>

Checkable::Checkable(QWidget *parent)
    : QMainWindow(parent) {

  viewst = new QAction("&View statusbar", this);
  viewst->setCheckable(true);
  viewst->setChecked(true);

  QMenu *file;
  file = menuBar()->addMenu("&File");
  file->addAction(viewst);

  statusBar();

  connect(viewst, SIGNAL(triggered()), this, SLOT(toggleStatusbar()));
}

void Checkable::toggleStatusbar() {
    
  if (viewst->isChecked()) {
      
      statusBar()->show();
  } else {
      
      statusBar()->hide();
  }
}

A checkable menu item toggles the visibility of the statusbar.

viewst = new QAction("&View statusbar", this);
viewst->setCheckable(true);
viewst->setChecked(true);

We create an actiona and make it checkable with the setCheckable method. The setChecked method makes it checked.

if (viewst->isChecked()) {
    
    statusBar()->show();
} else {
    
    statusBar()->hide();
}

Inside the toggleStatusbar method, we determine if the menu item is checked and hide or show the statusbar accordingly.

main.cpp

#include "checkable.h"

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

  window.resize(250, 150);
  window.setWindowTitle("Checkable menu");
  window.show();

  return app.exec();
}

This is the main file.

QToolBar

The QToolBar class provides a movable panel that contains a set of controls which provide a quick access to the application actions.

toolbar.h

#pragma once

#include <QMainWindow>
#include <QApplication>

class Toolbar : public QMainWindow {
    
  Q_OBJECT  

  public:
    Toolbar(QWidget *parent = 0);
};

The header file for the example.

toolbar.cpp

#include "toolbar.h"
#include <QToolBar>
#include <QIcon>
#include <QAction>

Toolbar::Toolbar(QWidget *parent)
    : QMainWindow(parent) {
    
  QPixmap newpix("new.png");
  QPixmap openpix("open.png");
  QPixmap quitpix("quit.png");
  
  QToolBar *toolbar = addToolBar("main toolbar");
  toolbar->addAction(QIcon(newpix), "New File");
  toolbar->addAction(QIcon(openpix), "Open File");
  toolbar->addSeparator();
  QAction *quit = toolbar->addAction(QIcon(quitpix), 
      "Quit Application");
  
  connect(quit, SIGNAL(triggered()), qApp, SLOT(quit()));
}

To create a toolbar, we inherit from the QMainWindow widget.

QToolBar *toolbar = addToolBar("main toolbar");

The addToolBar method creates a toolbar and returns a pointer to it.

toolbar->addAction(QIcon(newpix), "New File");
toolbar->addAction(QIcon(openpix), "Open File");
toolbar->addSeparator();

Here we add two actions and a separator to the toolbar.

main.cpp

#include "toolbar.h"

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

  window.resize(300, 200);
  window.setWindowTitle("QToolBar");
  window.show();

  return app.exec();
}

This is the main file.

Application skeleton

In the end of this part of the C++ Qt4 tutorial, we create an application skeleton. The example is based mainly on the QMainWindow widget.

skeleton.h

#pragma once

#include <QMainWindow>
#include <QApplication>

class Skeleton : public QMainWindow {
    
  Q_OBJECT  

  public:
    Skeleton(QWidget *parent = 0);
};

The header file for the example.

skeleton.cpp

#include "skeleton.h"
#include <QToolBar>
#include <QIcon>
#include <QAction>
#include <QMenu>
#include <QMenuBar>
#include <QStatusBar>
#include <QTextEdit>

Skeleton::Skeleton(QWidget *parent)
    : QMainWindow(parent) {
        
  QPixmap newpix("new.png");
  QPixmap openpix("open.png");
  QPixmap quitpix("quit.png");

  QAction *quit = new QAction("&Quit", this);

  QMenu *file;
  file = menuBar()->addMenu("&File");
  file->addAction(quit);

  connect(quit, SIGNAL(triggered()), qApp, SLOT(quit()));
  
  QToolBar *toolbar = addToolBar("main toolbar");
  toolbar->addAction(QIcon(newpix), "New File");
  toolbar->addAction(QIcon(openpix), "Open File");
  toolbar->addSeparator();
  
  QAction *quit2 = toolbar->addAction(QIcon(quitpix), 
      "Quit Application");
  connect(quit2, SIGNAL(triggered()), qApp, SLOT(quit()));

  QTextEdit *edit = new QTextEdit(this);  

  setCentralWidget(edit);

  statusBar()->showMessage("Ready");
}

Here we create a menu a toolbar and a statusbar.

QTextEdit *edit = new QTextEdit(this);  

setCentralWidget(edit);

We create a QTextEdit widget and place it into the central part of the QMainWindow widget.

main.cpp

#include "skeleton.h"

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

  window.resize(350, 250);
  window.setWindowTitle("Application skeleton");
  window.show();

  return app.exec();
}

This is the main file.

In this part of the Qt4 tutorial, we have covered menus and toolbars.

Ebooks

Menus and toolbars in Qt4

Simple menu

Icons, shortcuts, and separators

Checkable menu

QToolBar

Application skeleton