QCursor::pos() only works correctly if I change the Qt Creator theme.

Punkcake

I have created a mouseMoveEvent that should return the global coordinates of the cursor

void MainWindow::mouseMoveEvent(QMouseEvent *event)
{
    QPoint globalPos = event->pos();
    globalPos = QWidget::mapToGlobal(globalPos);
    ui->labelGlobal->setText(QString("%1 : %2").arg(globalPos.x()).arg(globalPos.y()));
}

, but if I move the cursor to the left-top corner of the screen, I get negative coordinates, even though the coordinates should be 0:0.
If I change the Qt Creator theme, everything works correctly, until I restart Qt Creator for the first time.

Punkcake

@Christian-Ehrlicher I disable Wayland in /etc/gdm3/custom.conf and reboot Ubuntu, everything worked correctly.

Thanks for the help!

SGaist

Hi and welcome to devnet,

What do you mean by "Qt Creator theme" ?

Which version of Qt are you using ?
On which platform ?

Punkcake

@SGaist Hi, I use Qt Creator 11.0.3 Based on Qt 6.4.3 (GCC 10.3.1 20210422 (Red Hat 10.3.1-1), x86_64) on Ubuntu 22.04.
I mean theme in Preferences->Environment->Interface

Pl45m4

@Punkcake said in QCursor::pos() only works correctly if I change the Qt Creator theme.:

Qt Creator 11.0.3 Based on Qt 6.4.3

That's not your Qt version you are using to create your app, that's what was used to build QtCreator itself.

QWidget::mapToGlobal(globalPos);

Does changing it to

this->mapToGlobal(globalPos);

make any difference?

Punkcake

@Pl45m4 I use Qt 6.6.0. I change code and no any difference.

Christian Ehrlicher

class MyMainWindow : public QMainWindow
{
public:
    void mouseMoveEvent(QMouseEvent *ev) override
    {
        QMainWindow::mouseMoveEvent(ev);
        const auto globalPos = mapToGlobal(ev->pos());
        qDebug() << globalPos << ev->globalPosition() << ev->pos();
    }
};

Works fine for me, even though the mapped and the global pos from the event differ sometimes (maybe due to rounding errors).

Punkcake

I think the problem is not in the code

Christian Ehrlicher

@Punkcake But you should still output QMouseEvent::globalPosition() and check it with the calculated one. I doubt it's a Qt problem but maybe within your window manager - what window manager do you use?

Punkcake

@Christian-Ehrlicher I output QMouseEvent::globalPosition() and got the following values:
QPoint(-111,-76) QPointF(-111,-76) QPoint(-111,-76)
QPoint(-112,-76) QPointF(-112,-76) QPoint(-112,-76)
QPoint(-113,-76) QPointF(-113,-76) QPoint(-113,-76)
QPoint(-114,-76) QPointF(-114,-76) QPoint(-114,-76)
QPoint(-115,-76) QPointF(-115,-76) QPoint(-115,-76)
QPoint(-116,-76) QPointF(-116,-76) QPoint(-116,-76)

How can I find out which window manager I'm using?

Punkcake

Maybe the problem is related to virtualization.

Christian Ehrlicher

@Punkcake said in QCursor::pos() only works correctly if I change the Qt Creator theme.:

Maybe the problem is related to virtualization.

Don't know - works fine with VirtualBox here. I think it's the window manager

How can I find out which window manager I'm using?

You should know if you run Gnome or KDE or whatever.

Punkcake

@Christian-Ehrlicher I disable Wayland in /etc/gdm3/custom.conf and reboot Ubuntu, everything worked correctly.

Thanks for the help!