RasterWidgetDelegate constructor Null safety

1. Flutter
2. widgets
3. RasterWidgetDelegate
4. RasterWidgetDelegate constructor

RasterWidgetDelegate class

1. Constructors
2. RasterWidgetDelegate
3. Properties
4. hashCode
5. hasListeners
6. runtimeType
7. Methods
8. addListener
9. dispose
10. noSuchMethod
11. notifyListeners
12. paint
13. removeListener
14. shouldRepaint
15. toString
16. Operators
17. operator ==