Programmatically control zooming & panning

[burhankhanzada]

Added feature to programmatically control zoom and panning which is helpful when need shortcuts but have to create new custom controller and move some methods to that. Please review it.

[hlvs-apps]

Hi, thanks for the effort. It looks like a good idea; however I have some concerns with your current implementation, mainly regarding the duplicate code within the update methods and the state tracking in general.

The common approach imo would be a bigger refactor, moving the state tracking to a single source of truth and the respective update methods to the new controller class, so they can be removed from/reduced to one liners in the BetterInteractiveViewerBaseState class, although that would mean removing these settings from the widget and moving them to the controller, which is a no-go for me because it would make using the widget much harder.

I think a better approach would be something like keeping all the state in the abstract BetterInteractiveViewerBaseState, and providing the pan and zoom methods there (making it available via a global key) and possibly providing a shrinked version of your InteractiveViewer2Controller that the BetterInteractiveViewerBaseState attaches automatically to, giving the controller a way to forward the method calls to the base class.

Also, I would like to keep some compatibility to the current interactive viewer transformattion controller, so the new controller should at least offer a factory like InteractiveViewer2Controller.wrapTransformationController(TransformationController controller)

[burhankhanzada]

Yeah i totally agree with you my solution have divided state but that was my poor man solution to able to work with this package as default implementation lack some functionality.

I think your approach would be better and backward compatible also.