How can I access Model index via contextMenuEvent?

Loquat

Hi,
I have a custom Model that inherits from QAbstractListModel and I use QListView to access the data in it.

I want to right click on a single item from the list and know which item from the Model that is.
Why in the below code, the returned "item" index is wrong and later not recognised by

myListView->model()->data(item).toString();

Please see the below code snippet:

void MyClass::contextMenuEvent(QContextMenuEvent* event)
{
    if (event->reason() == QContextMenuEvent::Mouse)
    {
        QModelIndex item = myListView->indexAt(event->pos());
   
        //blah, blah, blah
    }
}

VRonin

~~Probaby a matter of relative coordinates, try event->globalPos()~~

Edit: worng answer

Loquat

Nope, the index remains the same and looks like this in Watch:

index {r=0xffffffff c=0xffffffff p=0x00000000 ...} const QModelIndex &

Christian Ehrlicher

indexAt() expects local coordinates of the view, not of some other widget where you catch the contextMenuEvent. You have to translate it.

btw: https://doc.qt.io/qt-5/qwidget.html#customContextMenuRequested is the normal way to go here.

VRonin

Fully working minimal example:

#include <QApplication>
#include <QStandardItemModel>
#include <QListView>
#include <QDebug>
int main(int argc, char *argv[])
{
    QApplication app(argc,argv);
    QStandardItemModel model(5,1);
    for(int i=0;i<model.rowCount();++i)
        model.setData(model.index(i,0),i+1);

    QListView view;
    view.setModel(&model);
    view.setContextMenuPolicy(Qt::CustomContextMenu);
    QObject::connect(&view,&QListView::customContextMenuRequested,[&view](const QPoint &pos){
        qDebug() << view.indexAt(pos);
    });
    view.show();
    return app.exec();
}

Loquat

Thanks guys, that's looking well-promising now! The "Item" looks like a valid number now. Much appreciate your help!

However, what I'm trying to do next, fails. Would you mind having a look, please?

void MyClass::showContextMenu(const QPoint& pos)
{
    /* Handle global position */
    QPoint globalPos = deviceView->mapToGlobal(pos);
    QModelIndex item = deviceView->indexAt(pos);

    /* Create menu and insert some actions */
    QMenu rightClickMenu;
    rightClickMenu.addAction("Some Action");

    QAction* selectedMenuItem = rightClickMenu.exec(globalPos);  // does not work with "pos" either
    if (!selectedMenuItem)
    {
        return; // always end up here!
    }
...

Loquat

What I'm trying to do is:

open a QListView in my MainWindow (in fact, I open it in a Dock, that is in MainWindow, which then sets its widget as my QListView)
display data from the Model that my QListView is using
right-click on a particular row and select an item which will create another dedicated dock

How can I make sure that the right-click only works for the QListView? Because at the moment, it seems that I can click anywhere and it will show the right-click menu. Doing the below doesn't seem to work:

    MyListModel* myModel = new MyListModel();
    myView = new QListView;
    myView->setModel(myModel);

    /* Custom right-click menu */
    myView ->setContextMenuPolicy(Qt::CustomContextMenu);

    connect(myView, SIGNAL(customContextMenuRequested(QPoint)), this, SLOT(showContextMenu(QPoint)));

As you can see in the connect, signal-to-slot is from myView to "this" because showContextMenu is defined in "this", i.e. my class that instantiates QListView... is that all correct?

VRonin

@Loquat said in How can I access Model index via contextMenuEvent?:

is that all correct?

Yes