QGraphicsEllipseItem: ItemSendsScenePositionChanges move event?

[harakiri]

Hi,

i have a 4 vertices:

Vertex::Vertex(int x, int y) : QGraphicsEllipseItem(x-1,y-1,x+1,y+1)
{
			QPen currentPen = pen();
			currentPen.setColor(Qt::blue);
			currentPen.setWidth(3);
			setPen(currentPen);
			setAcceptsHoverEvents( true );
			setFlag( QGraphicsItem::ItemIsMovable, true );
			setFlag( QGraphicsItem::ItemSendsScenePositionChanges, true );
}

Vertex::Vertex(int x, int y) : QGraphicsEllipseItem(x-1,y-1,x+1,y+1)
{
			QPen currentPen = pen();
			currentPen.setColor(Qt::blue);
			currentPen.setWidth(3);
			setPen(currentPen);
			setAcceptsHoverEvents( true );
			setFlag( QGraphicsItem::ItemIsMovable, true );
			setFlag( QGraphicsItem::ItemSendsScenePositionChanges, true );
}

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that describe a polygon (QGraphicsPathItem)
they are added to a QGraphicsScene in a QGraphicsView.

So far, everything's fine; i can move the the vertices around, hover effects and so on are working fine.

But now, i want to adjust the polygon if a user changes a vertex.
Is there any event the QGraphicsEllipseItem emits when moved?
Or does the QGraphicsScene have an event to tell me it's content hast changed?

i am looking for something like:

connect(m_scene, SIGNAL(changed()),
            this,   SLOT(updatePolygon()));

connect(m_scene, SIGNAL(changed()),
            this,   SLOT(updatePolygon()));

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or

Vertex* vertex = new Vertex(event->x(), event->y());
connect(vertex, SIGNAL(ItemPositionHasChanged()),
	   this,   SLOT(updatePolygon()));

Vertex* vertex = new Vertex(event->x(), event->y());
connect(vertex, SIGNAL(ItemPositionHasChanged()),
	   this,   SLOT(updatePolygon()));

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but both didn't work