Called whenever a new instance of the custom clipper delegate class is provided to the clip object, or any time that a new clip object is created with a new instance of the custom painter delegate class (which amounts to the same thing, because the latter is implemented in terms of the former).
If the new instance represents different information than the old
instance, then the method should return true, otherwise it should return
false.
If the method returns false, then the getClip call might be optimized
away.
It's possible that the getClip method will get called even if
shouldReclip returns false or if the getClip method is never called
at all (e.g. if the box changes size).
Source
bool shouldReclip(@checked CustomClipper<T> oldClipper);