Hello,

You can also reimplement the item itemChange(GraphicsItemChange change, const QVariant &value) fonction. I use this to implement a snap to grid behaviour.

This is an example from the doc that keep item inside scene:

Qt Code: 
  1. QVariant Component::itemChange(GraphicsItemChange change, const QVariant &value)
  2.  {
  3.      if (change == ItemPositionChange && scene()) {
  4.          // value is the new position.
  5.          QPointF newPos = value.toPointF();
  6.          QRectF rect = scene()->sceneRect();
  7.          if (!rect.contains(newPos)) {
  8.              // Keep the item inside the scene rect.
  9.              newPos.setX(qMin(rect.right(), qMax(newPos.x(), rect.left())));
  10.              newPos.setY(qMin(rect.bottom(), qMax(newPos.y(), rect.top())));
  11.              return newPos;
  12.          }
  13.      }
  14.      return QGraphicsItem::itemChange(change, value);
  15.  }
To copy to clipboard, switch view to plain text mode