Popup Menu in QOpenGLWindow - how to do it?

[DavidRS]

I have a program that processes data and then generates an image which is then displayed in a QOpenGLWidow. I would like to have a popup menu on right mouse click to give a list of display options. The menu changes according to the properties of the data/image.

As far as I can see, QOpenGLWindow (and QWindow) do not have a contextMenuPolicy, so trying to detect a contextMenuEvent on a right click (as below) fails and nothing happens

void ViewData::contextMenuEvent(QContextMenuEvent *e)
{
      QMenu* menu =imageMenu;
      menu->exec(e->globalPos());
}

I wondered if creating a QContextMenuEvent on a right mouse click might help, but I'm not sure how to transmit it and by itself it does nothing.

[jsulm]

@DavidRS You could simply show the pop-up menu on right-click without transmitting QContextMenuEvent

[DavidRS]

Nope. If you do the following

void ViewData::mousePressEvent(QMouseEvent *e)
{
  switch(e->button())
  {
    // code for other buttons before here
      case (Qt::RightButton)
      {
        imageMenu->exec(e->globalPos());
        break;
      }
 }

The program crashes when you right click.
This is running under Linux and X11 with Qt ver 5.13.2

[SGaist]

Hi,

Might be a silly question but are you sure that imageMenu is valid ?

Can you show the stack trace you get ?

[DavidRS]

@SGaist You were right - the QMenu initialization was in a branch that was not being visited. Once I moved it before that branch it worked perfectly. Because there are no widgets the menu was created as

imageMenu = new QMenu(nullptr);

and was directly accessed through the right mouse click once the image was created.