Prevent QGraphicsItem from moving outside of QGraphicsScene

Question

I have a scene which has fixed dimensions from (0;0) to (481;270):

scene->setSceneRect(0, 0, 481, 270);

Inside of it, I have a custom GraphicsItem and I can move it thanks to the flag ItemisMovable, but I would like it to stay within the Scene; I actually mean I don't want it to have coordinates neither under (0;0) nor over (481;270).

I tried several solutions like overriding QGraphicsItem::itemChange() or even QGraphicsItem::mouseMoveEvent() but I still cannot manage to reach what I want to do.

What is the suitable solution for my needs? Do I use QGraphicsItem::itemChange() badly?

Thanks in advance.

Answer 1

You can override QGraphicsItem::mouseMoveEvent() like this:

YourItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
    QGraphicsItem::mouseMoveEvent(event); // move the item...

    // ...then check the bounds
    if (x() < 0)
        setPos(0, y());
    else if (x() > 481)
        setPos(481, y());

    if (y() < 0)
        setPos(x(), 0);
    else if (y() > 270)
        setPos(x(), 270);
}