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Using QMDIArea with Qt 4.4.

I am using QMdiArea

in Qt 4.4.

If a new project is created, I add some subframes to the QMdiArea

. I would like to prevent the user from closing the sub window at runtime. Sub-windows should only be closed if the entire application is closed or a new project is created.

How can i do this?

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2 answers


You need to define your own subWindow

. subclass QMdiSubWindow

and override closeEvent(QCloseEvent *closeEvent)

. you can manipulate it with an argument. eg:

void ChildWindow::closeEvent(QCloseEvent *closeEvent)
{
  if(/*condition C*/)
    closeEvent->accept();
  else
   closeEvent->ignore(); // you can do something else, like 
                         // writing a string in status bar ...
}

then subclass QMdiArea

and override QMdiArea::closeAllSubWindows ()

as follows:



class MainWindowArea : public QMdiArea
{
    Q_OBJECT
public:
    explicit MainWindowArea(QWidget *parent = 0);

signals:
    void closeAllSubWindows();
public slots:

};
// Implementation:
MainWindowArea::closeAllSubWindows()
{
    // set close condition (new project is creating, C = true)
    foreach(QMdiSubWindow* sub,this->subWindowList())
    {
        (qobject_cast<ChildWindow*>(sub))->close();
    }
}

you may also need to override the slot of close

your mdi area.

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You would do it the same way as for a top-level window: process and ignore the dispatched QCloseEvent. QMdiArea :: closeActiveSubWindow / QMdiArea :: closeAllSubWindows is simply called by QWidget :: close, which dispatches a closeEvent and confirms that it was received before continuing.



You can handle this event by subclassing QMdiSubWindow and overriding QWidget :: closeEvent, or by using an event filter to catch it.

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