detach method
override
Mark this render object as detached from its PipelineOwner.
Typically called only from the parent's detach, and by the owner to mark the root of a tree as detached.
Subclasses with children should override this method to
detach all their children after calling the inherited method,
as in super.detach().
Implementation
@override
void detach() {
_painter?.dispose();
_painter = null;
super.detach();
// Since we're disposing of our painter, we won't receive change
// notifications. We mark ourselves as needing paint so that we will
// resubscribe to change notifications. If we didn't do this, then, for
// example, animated GIFs would stop animating when a DecoratedBox gets
// moved around the tree due to GlobalKey reparenting.
markNeedsPaint();
}