describeApproximatePaintClip method Null safety

  1. @override
Rect? describeApproximatePaintClip(
  1. covariant RenderObject child
)
override

Returns a rect in this object's coordinate system that describes the approximate bounding box of the clip rect that would be applied to the given child during the paint phase, if any.

Returns null if the child would not be clipped.

This is used in the semantics phase to avoid including children that are not physically visible.

RenderObjects that respect a Clip behavior when painting must respect that same behavior when describing this value. For example, if passing Clip.none to PaintingContext.pushClipRect as the clipBehavior, then the implementation of this method must return null.

Implementation

@override
Rect? describeApproximatePaintClip(RenderObject child) {
  switch (clipBehavior) {
    case Clip.none:
      return null;
    case Clip.hardEdge:
    case Clip.antiAlias:
    case Clip.antiAliasWithSaveLayer:
      return _hasVisualOverflow ? Offset.zero & size : null;
  }
}