旋转后如何还原正在运行的动画

Question

I have some view states like StartingGame and GameStarted . If the user starts a game, I emit both states one after another and start a progress in the first event like following:

var d = Observable.interval(1000L, TimeUnit.MILLISECONDS)
            .takeWhile({ t -> t <= 45 })
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe {
                 // update a progress view that shows the remaining time of this turn...
            }

After rotation, my view state says, that it already has handled the start of the animation, so the animation is not shown.

How could I solve this in a mvi way?

Should I really emit all those events through the mvi state stream and increase the progress in my state on every event and update the view there?

Answer 1

Should I really emit all those events through the mvi state stream and increase the progress in my state on every event and update the view there?

Yes you should. It makes sense to do this and makes your app so much more testable.

You know how long the progress is running right (4500 milliseconds). You can make this part of the state

state = {
   ...
   animationRun = 90 ms,
   totalAnimationTime = 4500 ms
}

and in your Observable.interval() stream you basically increase animationRun .

Then do the following:

1. Your screen starts with:

   state = { ... animationRun = 0 ms, totalAnimationTime = 4500 ms }

   just start an animation for 4500ms

2. After rotating the screen: You know the last state like

   state = { ... animationRun = 1000 ms, totalAnimationTime = 4500 ms }

   Then you know that your animation must start with progress "1000" and run for 3500ms (3500 + 1000 = 4500)