Disabling the "eventFilter" trigger on child elements when implementing the window movement function.

Helge1980

Hi!
I'm trying to make the window move functionality, but there is one problem: I don't know how to disable this function on child elements for "ui->frame_hint" (three QPushButton buttons). I.e. when the cursor hits these buttons, the window " jumps". In other words, I need to move the window with the mouse cursor behind the ui->frame_hint object, except when the cursor falls on the child objects for ui->frame_hint.

bool MainWindow::eventFilter(QObject *watched, QEvent *event)
{
    if (watched == ui->frame_hint)
    {
        if (event->type() == QEvent::MouseButtonPress)
        {
            QMouseEvent* mouse_event = dynamic_cast<QMouseEvent*>(event);
            if (mouse_event->button() == Qt::LeftButton)
            {
                mouseClickCoordinate = mouse_event->pos();
                return false;
            }
        }
        else if (event->type() == QEvent::MouseMove)
        {
            QMouseEvent* mouse_event = dynamic_cast<QMouseEvent*>(event);
            if (mouse_event->buttons() & Qt::LeftButton)
            {
                this->move(mouse_event->globalPos() - mouseClickCoordinate);
                return false;
            }
        }
    }
    return false;
}

Thanks!

SGaist

Hi,

You should return the base class implementation rather than just false. You do not allow further processing doing that.

Note that in your implementation you return false whatever happens.

Helge1980

@SGaist

I replaced "return false" everywhere with

return QObject::eventFilter(watched, event);

but nothing has changed, still the same problem...

JonB

@Helge1980

Did that include the final return false at the end of your eventFilter()?
The base class of your MainWindow is presumably QMainWindow? So you must use return QMainWindow::eventFilter(watched, event); everywhere.

Helge1980

@JonB
Yes, there is also a return QMainWindow::eventFilter(watched, event) at the end of eventFilter ().
Now the final code looks like this:

bool MainWindow::eventFilter(QObject *watched, QEvent *event)
{
    if (watched == ui->frame_hint)
    {
        if (event->type() == QEvent::MouseButtonPress)
        {
            QMouseEvent* mouse_event = dynamic_cast<QMouseEvent*>(event);
            if (mouse_event->button() == Qt::LeftButton)
            {
                mouseClickCoordinate = mouse_event->pos();
                return QMainWindow::eventFilter(watched, event);
            }
        }
        else if (event->type() == QEvent::MouseMove)
        {
            QMouseEvent* mouse_event = dynamic_cast<QMouseEvent*>(event);
            if (mouse_event->buttons() & Qt::LeftButton)
            {
                this->move(mouse_event->globalPos() - mouseClickCoordinate);
                return QMainWindow::eventFilter(watched, event);
            }
        }
    }
    return QMainWindow::eventFilter(watched, event);
}

Helge1980

It was obtained using an additional variable

bool clickPressedFlag = false;

and using

QEvent::MouseButtonRelease

Working code:

bool MainWindow::eventFilter(QObject *watched, QEvent *event)
{
    if (event->type() == QEvent::MouseButtonRelease)
    {
        QMouseEvent* mouse_event = dynamic_cast<QMouseEvent*>(event);
        if (mouse_event->button() == Qt::LeftButton)
        {
            clickPressedFlag = false;
            return QMainWindow::eventFilter(watched, event);
        }
    }

    if (watched == ui->frame_top_btns)
    {
        if (event->type() == QEvent::MouseButtonPress)
        {
            QMouseEvent* mouse_event = dynamic_cast<QMouseEvent*>(event);
            if (mouse_event->button() == Qt::LeftButton)
            {
                mouseClickCoordinate = mouse_event->pos();
                clickPressedFlag = true;
                return QMainWindow::eventFilter(watched, event);
            }
        }
        else if ((event->type() == QEvent::MouseMove) && clickPressedFlag == true)
        {
            QMouseEvent* mouse_event = dynamic_cast<QMouseEvent*>(event);
            if (mouse_event->buttons() & Qt::LeftButton)
            {
                this->move(mouse_event->globalPos() - mouseClickCoordinate);
                return QMainWindow::eventFilter(watched, event);
            }
        }
    }
    return QMainWindow::eventFilter(watched, event);
}