Qt/C++ - Lesson 012. QShortcut – How to work with Hot Keys in Qt?

QShortcut, QShortcut example, Qt

Even in the official documentation on the topic QShortcut written not so much, so it's probably a note not to forget, not a full-fledged article. Just a few words about how to connect QShortcut entity that will be responsible for processing pressing a hotkey or keyboard shortcuts, such as Ctrl + D .

Project structure for QShortcut

The project structure is so trivial that I will not even bring it in this article. I shall confine myself to only those words that we will work with two files:

• mainwindow.h
• mainwindow.cpp

And even mainwindow.ui file will not touch this project. As it will be created by default, so it and leave.

mainwindow.h

The header file is required to declare two objects QShortcut, as well as for the treatment of hot keystrokes methods.

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include <QShortcut>
#include <QMessageBox>
 
namespace Ui {
class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
private slots:
    // slots for handlers of hotkeys
    void slotShortcutF11();
    void slotShortcutCtrlD();
 
private:
    Ui::MainWindow  *ui;
    QShortcut       *keyF11;    // Entity of F11 hotkey
    QShortcut       *keyCtrlD;  // Entity of Ctrl + D hotkeys
};
 
#endif // MAINWINDOW_H

mainwindow.cpp

Minimal setup a hotkey is:

• to initialize the object, which will be responsible for the hot key or shortcut;
• transfer of hot keys code into object;
• connecting slot handler to signal of QShortcut object.

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
    keyF11 = new QShortcut(this);   // Initialize the object
    keyF11->setKey(Qt::Key_F11);    // Set the key code
    // connect handler to keypress
    connect(keyF11, SIGNAL(activated()), this, SLOT(slotShortcutF11()));
 
    keyCtrlD = new QShortcut(this); // Initialize the object
    keyCtrlD->setKey(Qt::CTRL + Qt::Key_D); // Set the key code
    // connect handler to keypress
    connect(keyCtrlD, SIGNAL(activated()), this, SLOT(slotShortcutCtrlD()));
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
/* Slot handler of F11
 * */
void MainWindow::slotShortcutF11()
{
    /* This handler will make switching applications in full screen mode
     * and back to normal window mode
     * */
    if(this->isFullScreen()){
        this->showNormal();
    } else {
        this->showFullScreen();
    }
}
 
/* Slot handler for Ctrl + D
 * */
void MainWindow::slotShortcutCtrlD()
{
    /* For the treatment of a combination of keys Ctrl + D
     * will do the Message Box ,
     * which will signal that has been pressed a hotkey
     * */
    QMessageBox::information(this,
                             "Горячая клавиша",
                             "Мои поздравления!!! Горячая клавиша работает",
                             QMessageBox::Ok);
}

Result

This example shows one way to specify keyboard shortcuts, while the official documentation gives examples of several ways:

setKey(0);                  // signal is not invoked
setKey(QKeySequence());     // signal is not invoked
setKey(0x3b1);              // Set up of key code
setKey(Qt::Key_D);          // 'd', specify the key code via the directive 'define'
setKey('q');                // 'q', specify the key code via the symbol
setKey(Qt::CTRL + Qt::Key_P);       // Ctrl+P, specify the hotkeys via the directive define
setKey("Ctrl+P");           // Ctrl+P, direct writing shortcuts
 
/* Keyboard shortcuts necessary to register through the sign "+" */

As a result, you should have an application that by pressing the F11 key is set to full screen mode and rolled back into the normal display window and by pressing the key combination Ctrl + D is the MessageBox, which indicates that you press a combination of keys.

Application with using QShortcut