Reusing a QMenu within multiple Qmenu

Question

Hi all,

I have some code generating a dynamically filled QMenu depending on some data (I will call it thisMenu). The QMenu thisMenu is created, taking some "main" QWidget as parent and is added to a QMenuBar within this QWidget (menuBar.addMenu(&thisMenu). Latter on, I want the user to be able of accessing thisMenu from a context menu (the user right click on some portion of the QWidget, which pops a QMenu (called contextMenu) with some actions, and the previous QMenu as a sub-menu).

If I reuse the QMenu that I first created with contextMenu.addMenu(&thisMenu) I find out that, even if contextMenu pops at the right global position, thisMenu is always translated to some other position and appearing sometimes above, sometimes under contextMenu.

I can test that this is linked to the parenting chain : thisMenu is not a child of contextMenu, if I create it a child of contextMenu, everything is fine. Is there a way of cleanly handling this case without recreating a QMenu similar to thisMenu, or changing the parent of thisMenu; i.e. reusing thisMenu in both QMenuBar and in some context menu/QMenu? In other what is the proper way of handling parenting chain for QMenu and sharing QMenu?

Thank you,

score 3 · Accepted Answer · answered Sep 23 '14 at 06:40

In other what is the proper way of handling parenting chain for QMenu and sharing QMenu?

You cannot share a QMenu across multiple places -- each QMenu can only exist in one place at a time. You should create separate QMenus: One for your menu bar and one for your context menu.

A simple way is to put your menu-generating code in a for-loop, to create multiple identical menus.

May I ask why you want to reuse your QMenu?

I can test that this is linked to the parenting chain : thisMenu is not a child of contextMenu

Yes, that is described in the documentation. When you add one QMenu to another, the parent doesn't change: http://qt-project.org/doc/qt-5/QMenu.html#addMenu

if I create it a child of contextMenu, everything is fine.

The position of a widget is always painted in a position relative to its parent. (Remember: A QMenu is a QWidget)

score 2 · Answer 2 · edited May 23 '17 at 12:02

Following JKSH's answer, I decided to use a function to duplicate QMenu, without duplicating the QAction in it (they are not inheriting QWidget), hence conserving all established connections :

void duplicateMenu(QMenu* dst, QMenu& origin)
{
    QMenu* sub = dst->addMenu(origin.title());
    QList<QAction*> actions=origin.actions();

    for(QList<QAction*>::iterator it=actions.begin(); it!=actions.end(); it++)
    {
        QMenu* itMenu = (*it)->menu();

        if(itMenu!=NULL)
            duplicateMenu(sub, *itMenu);
        else
            sub->addAction(*it);
    }
}

Reusing a QMenu within multiple Qmenu

2 Answers2