Question

Is it possible to have an event filter on a QGraphicsItem? Eventfilter has a param that gives you a QObject, but since QGraphicsItem isn’t derived from QObject, then how would it work?

Answer 1

Edit: Use QGraphicsItem::installSceneEventFilter as suggested in @Frank’s answer. Example:

QGraphicsScene scene;
QGraphicsEllipseItem *ellipse = scene.addEllipse(QRectF(-10, -10, 20, 20));
QGraphicsLineItem *line = scene.addLine(QLineF(-10, -10, 20, 20));
line->installSceneEventFilter(ellipse);
// line's events are filtered by ellipse's sceneEventFilter() function.
ellipse->installSceneEventFilter(line);
// ellipse's events are filtered by line's sceneEventFilter() function.

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The first thing that popped into my mind was this:

Create a new class, derived from both QGraphicsItem and QObject, since these are unrelated (as far as a glance at the docs tells me), you should have what you wanted.

…. But then I looked at the docs more closely and found QGraphicsObject, which is probably exactly what you want, it even already has the member eventFilter