Privacy policyContactsAbout siteOpinionsGitHubDonate
© EVILEG 2015-2018
Recommend hosting
TIMEWEB

Qt/C++ - Tutorial 063. Adding windows inside the main application window using QMdiArea

QMdiArea, QWidget, Qt

Many applications, like a photoshop, can open projects (images, texts, etc.) inside windows that open inside the main application window. Qt provides a similar function as QMdiArea . In an object of this class, you can place class objects inherited from the QWidget class, and accordingly the QWidget class. These objects will display as windows, only they will be located inside QMdiArea .

Let's see an example with a window inside the window.

Project structure

The following files are included in the project:

  • MdiWindow.pro - project profile, created by default;
  • main.cpp - the startup file of the program with the main function, created by default;
  • mainwindow.h - header file of the main application window;
  • mainwindow.cpp - the source code file for the main application window;
  • mainwindow.ui - form of the main application window;
  • icons.qrc - resource file, contains one icon.

Files MdiWindow.pro and main.cpp will not be considered, since they are created by default. The file icons.qrc contains one icon, which is visible on the toolbar of the main application window. This button is responsible for creating an additional application window and is added through the graphic designer. This Action is only needed to emit a signal to add new windows to QMdiArea .

Now let's move on to the essence of the project.

mainwindow.h

Header file of the main application window. Contains the declaration of the pointer to the QMdiArea object, as well as the declaration of the slot for adding new windows, which was created through the graphic designer.

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QMdiArea>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private slots:
    void on_actionAddWindow_triggered();

private:
    Ui::MainWindow *ui;
    QMdiArea * mdiArea;  // Area in which windows will be added
};

#endif // MAINWINDOW_H

mainwindow.cpp

The QMdiArea object is installed as the central widget for the main application window. Also, configure the scrollbars so that they appear only when necessary. In the add window add a QWidget object with an inscription. There is one point. If QWidget does not contain any content, it will open with a minimum size, even if you size it. And only when you try to move the window, this widget will take the size displayed.

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

#include <QGridLayout>
#include <QLabel>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    mdiArea = new QMdiArea(this);  // init QMdiArea
    // configure scrollbars
    mdiArea->setHorizontalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    mdiArea->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    // Set Mdi Area as the central widget
    setCentralWidget(mdiArea);
}

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

void MainWindow::on_actionAddWindow_triggered()
{
    // Create a widget that will be a window
    QWidget *widget = new QWidget(mdiArea);
    // Adding layout to it
    QGridLayout *gridLayout = new QGridLayout(widget);
    widget->setLayout(gridLayout);
    // Adding an label to the widget
    QLabel *label = new QLabel("Hello, I am sub window!!!", widget);
    gridLayout->addWidget(label);

    // Adding a widget as a sub window in the Mdi Area
    mdiArea->addSubWindow(widget);
    // Set the window title
    widget->setWindowTitle("Sub Window");
    // And show the widget
    widget->show();
}

Download the project with an example QMdiArea

10% refund of hotel reservation amount on Booking
10% refund of hotel reservation amount on Booking
We offer a link with a 10% return on the amount of the order when booking a hotel through Booking

Comments

Only authorized users can post comments.
Please, Log in or Sign up
d
April 26, 2019, 2:45 a.m.
djanaibekova_0301@mail.ru

C++ - Тест 003. Условия и циклы

  • Result:42points,
  • Rating points-8
Z
April 25, 2019, 8:02 p.m.
ZadvornyAlexey

C++ - Test 001. The first program and data types

  • Result:60points,
  • Rating points-1
m
April 24, 2019, 2:30 p.m.
maksImkа

C++ - Тест 003. Условия и циклы

  • Result:50points,
  • Rating points-4
Last comments
April 21, 2019, 4:22 p.m.
Евгений Легоцкой

Через метод setIcon table.horizontalHeaderItem(0).setIcon("qrc://path/to/icon.png")
April 21, 2019, 3:48 p.m.
Евгений Легоцкой

Добрый день! Спасибо за комментарий. Там действительно лучше будет сделать с инициализацией по умолчанию.
U
April 18, 2019, 3:37 p.m.
Unreal_man

А как иконку в хедер задать?
u
April 18, 2019, 2:15 a.m.
uaa

доброго времени,большое спасибо за пример для начинающего)при адаптации к своему проекту столкнулся с таким ньансом:в vepolyline.h в 47 строке нужна инициализация по умолчанию: int m_pointF...
E
April 11, 2019, 12:49 p.m.
Evgeny

Спасибо за ответ) У меня компоновщик на нее ругался просто. Оказалось, просто забыл Q_OBJECT в начале класса указать.
Now discuss on the forum
April 25, 2019, 10:51 a.m.
Ruslan Polupan

Изменил функциютеперь работает. bool ModelTerminals::setData(const QModelIndex &index, const QVariant &value, int role){ Q_UNUSED(role) if(!index.isValid()) {return false;...
April 24, 2019, 6:20 a.m.
Ruslan Polupan

я так понимаю надо инфорация об устройствах.Я бы пробовал так rust@suse:~> lsblk -PNAME="sda" MAJ:MIN="8:0" RM="0" SIZE="111,8G" RO="0" TYPE="disk" MOUNTPOINT=""NAME="sda1" MAJ:MIN="8...
April 21, 2019, 4:16 p.m.
Евгений Легоцкой

Приветствую Нужно сохранять где-то выбранное значение, а потом восстанавливать его. Или использовать QSettings или добавить метод open(), в который передавать начальные значения для того...
R
April 19, 2019, 9:55 a.m.
RED_Spider

мені важко це зараз навіть перевірити, тому що знайшов коміт, це ще було в 2016 році, і цей код не буде працювати коректно зараз, єдине скажу що це були QThread
Join us in social networks

For registered users on the site there is a minimum amount of advertising