CODEWITHSUNDEEP
c++windowsqt
Omar Murcia
Omar Murcia

Reputation: 567

How to center a QMainWindow

I'm using Qt but I don't know how to center a QMainWindow window. I wrote this code, but it doesn't works. Thanks in advance.

QRect screenGeometry = QApplication::desktop()->screenGeometry();
int x = (screenGeometry.width() - w->width()) / 2;
int y = (screenGeometry.height() - w->height()) / 2;
w->move(x, y); // w is a QMainWindow pointer

I get this:

enter image description here

Upvotes: 5

Views: 7762

Answers (5)

8Observer8
8Observer8

Reputation: 1144

These functions are obsolete:

QApplication::desktop()->screenGeometry()
QApplication::desktop()->availableGeometry()
QDesktopWidget::screen()

Use QScreen instead:

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QScreen>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    move(screen()->availableGeometry().center() - frameGeometry().center());
}

Upvotes: 9

BaiJiFeiLong
BaiJiFeiLong

Reputation: 4609

One complete example of python version

from PySide2.QtCore import QRect, QPoint
from PySide2.QtWidgets import QApplication, QMainWindow

QApplication()
mainWindow = QMainWindow()
mainWindow.resize(1280, 720)
mainWindow.move(mainWindow.screen().geometry().center()
                - QRect(QPoint(), mainWindow.frameGeometry().size()).center())
mainWindow.show()
QApplication.exec_()

frameGeometry() may not have a zero top-left, so we only need the size.

Upvotes: 0

happ
happ

Reputation: 41

the following code works in the latest version of Qt 6.4.1

#include <QApplication>
#include <QScreen>

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

    int width = w.frameGeometry().width();
    int height = w.frameGeometry().height();

    QScreen *screen = a.primaryScreen();

    int screenWidth = screen->geometry().width();
    int screenHeight = screen->geometry().height();

    w.setGeometry((screenWidth/2)-(width/2), (screenHeight/2)-(height/2), width, height);

    w.show();
    return a.exec();
}

Upvotes: 3

AlexDarkVoid
AlexDarkVoid

Reputation: 542

There's a shorter solution I saw somewhere:

show();
move(
    QApplication::desktop()->screen()->rect().center()
    - frameGeometry().center()
);

Yet, for some weird reason, the window still does not appear exactly at the center.

Upvotes: 0

Omar Murcia
Omar Murcia

Reputation: 567

Thank you to everybody. I already solved my problem, using this code.

w->setFixedSize(400, 400);
int width = w->frameGeometry().width();
int height = w->frameGeometry().height();
QDesktopWidget wid;
int screenWidth = wid.screen()->width();
int screenHeight = wid.screen()->height();
w->setGeometry((screenWidth/2)-(width/2),(screenHeight/2)-(height/2),width,height);
w->show();

I get this:

enter image description here

Upvotes: 2

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