allRenderObjects property

Iterable<RenderObject> allRenderObjects

Render objects of all the widgets currently in the widget tree (lazy pre-order traversal).

This will almost certainly include many duplicates since the render object of a StatelessWidget or StatefulWidget is the render object of its child; only RenderObjectWidgets have their own render object.

Implementation 

Iterable<RenderObject> get allRenderObjects {
  TestAsyncUtils.guardSync();
  return allElements
         .map<RenderObject>((Element element) => element.renderObject);
}