Showing a popup menu on QGraphicsScene click or right click

Question

Is there a way to show a popup when the user right clicks on an empty portion of the scene?

I'm new at Qt and I've tried slots and subclassing, but to no avail.

No such slot and, respectively:

"error: 'QMouseEvent' has not been declared"

when trying to implement the onMouseRelease event.

Answer 1

QGraphicsView is the widget used for displaying the contents of the QGraphicsScene. So the correct place to implement the context menu (popup menu) is the QGraphicsView.

You need to reimplement the contextMenuEvent function is your own class inherited from QGraphicsView:

void YourGraphicsView::contextMenuEvent(QContextMenuEvent *event)
{
    QMenu menu(this);
    menu.addAction(...);
    menu.addAction(...);
    ...
    menu.exec(event->globalPos());
}

See also the Qt's Menus Example.

Answer 2

You can re-implement the contextMenuEvent method of the QGraphicsScene class, which will give you access to the scene coordinates as well as the screen coordinates (as opposed to QGraphicsView, which also works but doesn't have this information):

void YourGraphicsScene::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
    // event->scenePos() is available
    QMenu menu(this);
    menu.addAction(...);
    menu.addAction(...);
    ...
    menu.exec(event->screenPos());
}