What method is called when a QGraphicsItem get selected

Question

Probably a trick question, but I can't find the answer.

I need to know when a QGraphicsItem gets selected. There must be a method that's called.

I know QGraphicsItem::itemChange() but it's called too often.

Is there a better method ?

thx

edit : With this

if(change == ItemSelectedChange && scene()){
    cout << "haha " << i++ << endl;
}

I get two calls every selection change.

Harbert

Answer 1

You should take value into consideration in the QGraphicsItem::itemChange method. What you want is probably something like this:

QVariant YourItem::itemChange(GraphicsItemChange change, const QVariant &value)
{
    if (change == QGraphicsItem::ItemSelectedChange)
    {
        if (value == true)
        {
            // do stuff if selected
        }
        else
        {
            // do stuff if not selected
        }
    }

    return QGraphicsItem::itemChange(change, value);
}

Cableway

Thx Works better than what I found : add && this.isSelected() in the if. – Harbert

@Anthony, I have a question on the else part. When I select another graphics item, the else part is getting triggered. I understand that. I am facing an issue that i need to get the else part triggered while on mouse press on another graphics item. Now it is triggering only when i press and release the mouse button on another graphics item. Is there any solution for this ? – Cure

@Cure I would try calling scene()->clearSelection() in the other item's mousePressEvent to ensure that this item gets deselected on a mouse press. – Cableway

Answer 2

QGraphicsScene::selectionChanged

Mccready

You'd have to iterate over all selected items and manually set the ones in question selected. – Etheleneethelin