Changing mouse cursor in a QObject - QGraphicsItem inherited class

Question

I would like to change my mouse cursor when it is in a graphics item (MyCircle inherits from QObject and QGraphicsItem). Had my class inherited from <

Answer 1

QGraphicsItem already has a method for changing the cursor, so you don't need to manually play around with hover events:

QGraphicsItem::setCursor(const QCursor &cursor)

http://doc.qt.io/qt-5/qgraphicsitem.html#setCursor

PS: The dual inheritance of QWidget and QGraphicsItem you do is also a bad idea, only inherit from QGraphicsItem.

Answer 2

You can probably use hover events.

In your class constructor make sure you do...

setAcceptHoverEvents(true);

Then override hoverEnterEvent and hoverLeaveEvent.

virtual void hoverEnterEvent (QGraphicsSceneHoverEvent *event) override
{
  QGraphicsItem::hoverEnterEvent(event);
  QApplication::setOverrideCursor(Qt::PointingHandCursor);
}

virtual void hoverLeaveEvent (QGraphicsSceneHoverEvent *event) override
{
  QGraphicsItem::hoverLeaveEvent(event);
  QApplication::setOverrideCursor(Qt::ArrowCursor);
}

As a side note: do you actually inherit from both QObject and QGraphicsItem? If so, you could probably achieve the same goal by simply inheriting from QGraphicsObject.

Edit 1: In answer to...

I have the pointing hand icone in my whole bounding rect, how can I reduce the area only to my drawing (in this case a circle) ?

Override QGraphicsItem::shape to return a QPainterPath representing the actual shape...

virtual QPainterPath shape () const override
{
  QPainterPath path;

  /*
   * Update path to represent the area in which you want
   * the mouse pointer to change.  This will probably be
   * based on the code in your 'paint' method.
   */
  return(path);
}

Now override QGraphicsItem::hoverMoveEvent to make use of the shape method...

virtual void hoverMoveEvent (QGraphicsSceneHoverEvent *event) override
{
  QGraphicsItem::hoverMoveEvent(event);
  if (shape().contains(event->pos())) {
    QApplication::setOverrideCursor(Qt::PointingHandCursor);
  } else {
    QApplication::setOverrideCursor(Qt::ArrowCursor);
  }
}

The above could, obviously, have an impact on performance depending on the complexity of the shape drawn and, hence, the QPainterPath.

(Note: rather than using QGraphicsItem::shape you could do a similar thing with QGraphicsItem::opaque instead.)