PhotoViewScaleStateController constructor Null safety

1. photo_view package
2. documentation
3. photo_view
4. PhotoViewScaleStateController
5. PhotoViewScaleStateController constructor

PhotoViewScaleStateController class

1. Constructors
2. PhotoViewScaleStateController
3. Properties
4. hasChanged
5. hashCode
6. isZooming
7. outputScaleStateStream
8. prevScaleState
9. runtimeType
10. scaleState
11. Methods
12. addIgnorableListener
13. dispose
14. noSuchMethod
15. removeIgnorableListener
16. reset
17. setInvisibly
18. toString
19. Operators
20. operator ==