Qt/C++ - Lesson 002. QSystemTrayIcon - How to minimize the application to the system tray?

QSystemTrayIcon, Tray, qt, трей

Similar article on PyQt5/Python

Today will discuss the way to turn off the application, the Qt framework, written in, the operating system tray using QSystemTrayIcon class. This function is very useful for applications that need to run in the background for a long time mode. For example, video or audio playback application.

Therefore we will work with following questions:

• How to teach your program minimized to tray;
• How to make a popup menu for the tray icon of your applications;
• How to disable this feature if it is not needed.

The project structure for QSystemTrayIcon

The project is created as an application Qt Widgets, where files are created by default:

• Tray.pro - профайл;
• mainwindow.h - header file of the main application window;
• mainwindow.cpp - source window;
• main.cpp - the main source file from which the application starts;
• mainwindow.ui - form of the main application window.

mainwindow.ui

For the testing will create a simple and unremarkable mold with a check-box.

Object name QCheckBox following - tree CheckBox

Tray.pro

This file is left with the default settings.

#-------------------------------------------------
#
# Project created by QtCreator 2015-08-10T17:18:30
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Tray
TEMPLATE = app


SOURCES += main.cpp\
        mainwindow.cpp

HEADERS  += mainwindow.h

FORMS    += mainwindow.ui

main.cpp

This file is also not subject to change

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

mainwindow.h

The header has made changes as we need to keep track of the window closing event, as well as the need to create a handler for clicks on the application icon in the system tray. Also in the file, do not forget to connect all the necessary libraries. Otherwise, the project will not compile.

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QCloseEvent>
#include <QSystemTrayIcon>
#include <QAction>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

protected:
    /* Virtual function of the parent class in our class
     * Overridden to change the behavior of the application,
     * That it is minimized to tray when we want
     */
    void closeEvent(QCloseEvent * event);

private slots:
    /* The slot that will accept the signal from the event
     * Click on the application icon in the system tray
     */
    void iconActivated(QSystemTrayIcon::ActivationReason reason);

private:
    Ui::MainWindow          * ui;
    /* Declare the object of future applications for the tray icon */
    QSystemTrayIcon         * trayIcon;
};

#endif // MAINWINDOW_H

mainwindow.cpp

The whole logic of the application under test laid down in this class. The application will minimize to the system tray only if the tick checkbox is checked. Instead checkbox can be a variable or any other way of storing information about the need for this function to work.

At the same time, to exit the application when the marked check box, the corresponding item in the context menu.

Also, when the application is minimized to tray, it pops up a message that informs the user of the event.

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    this->setWindowTitle("Tray Program");

    /* Initialize the tray icon, set the icon of a set of system icons,
     * As well as set a tooltip
     * */
    trayIcon = new QSystemTrayIcon(this);
    trayIcon->setIcon(this->style()->standardIcon(QStyle::SP_ComputerIcon));
    trayIcon->setToolTip("Tray Program" "\n"
                         "Работа со сворачиванием программы трей");
    /* After that create a context menu of two items */
    QMenu * menu = new QMenu(this);
    QAction * viewWindow = new QAction(trUtf8("Развернуть окно"), this);
    QAction * quitAction = new QAction(trUtf8("Выход"), this);

    /* connect the signals clicks on menu items to by appropriate slots.
     * The first menu item expands the application from the tray,
     * And the second menu item terminates the application
     * */
    connect(viewWindow, SIGNAL(triggered()), this, SLOT(show()));
    connect(quitAction, SIGNAL(triggered()), this, SLOT(close()));

    menu->addAction(viewWindow);
    menu->addAction(quitAction);

    /* Set the context menu on the icon
     * And show the application icon in the system tray
     * */
    trayIcon->setContextMenu(menu);
    trayIcon->show();

    /* Also connect clicking on the icon to the signal processor of this press 
     * */
    connect(trayIcon, SIGNAL(activated(QSystemTrayIcon::ActivationReason)),
            this, SLOT(iconActivated(QSystemTrayIcon::ActivationReason)));
}

MainWindow::~MainWindow()
{
    delete ui;
}

/* The method that handles the closing event of the application window
 * */
void MainWindow::closeEvent(QCloseEvent * event)
{
    /* If the window is visible, and the checkbox is checked, then the completion of the application
     * Ignored, and the window simply hides that accompanied
     * The corresponding pop-up message
     */
    if(this->isVisible() && ui->trayCheckBox->isChecked()){
        event->ignore();
        this->hide();
        QSystemTrayIcon::MessageIcon icon = QSystemTrayIcon::MessageIcon(QSystemTrayIcon::Information);

        trayIcon->showMessage("Tray Program",
                              trUtf8("Приложение свернуто в трей. Для того чтобы, "
                                     "развернуть окно приложения, щелкните по иконке приложения в трее"),
                              icon,
                              2000);
    }
}

/* The method that handles click on the application icon in the system tray
 * */
void MainWindow::iconActivated(QSystemTrayIcon::ActivationReason reason)
{
    switch (reason){
    case QSystemTrayIcon::Trigger:
        /* The event is ignored if the checkbox is not checked
         * */
        if(ui->trayCheckBox->isChecked()){
            /* otherwise, if the window is visible, it is hidden,
             * Conversely, if hidden, it unfolds on the screen
             * */
            if(!this->isVisible()){
                this->show();
            } else {
                this->hide();
            }
        }
        break;
    default:
        break;
    }
}

Conclusion

If the project is successful build, your application will roll easily in the tray kolachikom. An example of the application QSystemTrayIcon shown in the following video: