QListWidget selection, preventing selection and revert to previous?

[SPlatten]

When the currentItemChanged signal occurs, in the slot I look for changes in other related controls and as a result I get either true to allow the change or false to prevent the change.

The question is how do I instruct QListWidget to revert back to the previous selection?

In the slot I have the parameters:

QListWidgetItem* pobjCurrent, QListWidgetItem* pobjPrevious

Based on the result I've tried:

if ( blnOkToChange != true ) {
    setCurrentItem(pobjPrevious);
    return;
}

This doesn't work.

Edit, I've also tried:

if ( blnOkToChange != true ) {
    pobjCurrent->setSelected(false);
    pobjPrevious->setSelected(true);
    return;
}

This doesn't work at all.

[SPlatten]

@JonB , so far all efforts at trying to prevent the selection have failed.

if ( blnOkToChange != true ) {
//Select previous selection and exit
    QListWidgetItem* pobjItem(pobjPrevious);
    QTimer::singleShot(100, this, [pobjItem]() {
        pobjItem->setSelected(true);
    });
    return;
}

Thinking about this issue, I think I will change the approach and when any of the controls are edited I will disable the list widget until the any changes have been submitted.

[JonB]

@SPlatten
currentItemChanged is only a signal to say it has happened, after the change has been made. It does not offer "reject".

I would have thought your code would work, so long as you are correctly checking for recursive call, because I think you will get the signal again for the change back. You may have to set both current item & selected item.

If it does not work, presumably either subclass QListWidget to handle, or install event filter on the it and handle check there, or try your revert-select on a timer immediately afterward to allow the current signal-slot to exit as-is. Not very elegant, but might suffice.

[SPlatten]

@JonB, thank you, I added this to the top of the slot of handle recursion:

    if ( pobjCurrent == pobjPrevious ) {
    //Ignore!
        return;
    }

It still doesn't work. I get a prompt, if I answer no I can see it drops into the logic:

    if ( blnOkToChange != true ) {
    //Select previous selection and exit
        setCurrentItem(pobjPrevious);
        return;
    }

But the display still shows the new selection.

[Christian Ehrlicher]

setCurrentItem() does not set a selection but the current index. current index has nothing to do with the current selection.

[SPlatten]

@Christian-Ehrlicher , thank you, then how to ?

[JonB]

@SPlatten
Like I said earlier, you probably want to set both current item and selection for your purpose? You have to decide.

[SPlatten]

@JonB , I've just tried:

    if ( blnOkToChange != true ) {
    //Select previous selection and exit
        QTimer::singleShot(50, [pobjCurrent, pobjPrevious]() {
            pobjCurrent->setSelected(false);
            pobjPrevious->setSelected(true);
        });
        return;
    }

Still not right, the list selection doesn't revert from the new selection.

[JonB]

@SPlatten
I find that hard to believe, don't you? You are just calling selection on a timer, why should that not work? Do some debugging of your code's behaviour. For all I know, to set a QListWidget's selection you must do something on the QListWidget, not on the items? Have you even tested your setSelected() call in any circumstance?

[SPlatten]

@JonB , so far all efforts at trying to prevent the selection have failed.

if ( blnOkToChange != true ) {
//Select previous selection and exit
    QListWidgetItem* pobjItem(pobjPrevious);
    QTimer::singleShot(100, this, [pobjItem]() {
        pobjItem->setSelected(true);
    });
    return;
}

Thinking about this issue, I think I will change the approach and when any of the controls are edited I will disable the list widget until the any changes have been submitted.

[SimonSchroeder]

@SPlatten said in QListWidget selection, preventing selection and revert to previous?:

Thinking about this issue, I think I will change the approach and when any of the controls are edited I will disable the list widget until the any changes have been submitted.

You don't have to fully disable the list widget (which is when it is grayed out), but just blockSignals for the list widget.

If I'm not mistaken I always go through the model to tweak the selection. This is the only way I have found so far to work properly.