Reviewer / Previewer don't store/restore state on restart (switch to night view while using them to see)

[timo-a]

1) go to Browser select preview on a card pull side bar in, switch to night mode ->crash

2) review card A pull side bar in, switch to night mode -> another card B is on top, card A has disappeared back into the deck

[jeffreyj100]

Is it right to allow the user the option of swiping the nav menu and toggling night mode while on preview view, as edit note view does not have this option?

[hssm]

The way we restart activities when toggling night mode doesn't really work for the previewer (hierarchy and state are both lost). So unless we come up with a better way to do that in the future, I think the quick and easy solution to avoiding the crash is indeed to disable the nav drawer.

As for point 2 in the original issue, that is not what usually happens, so I don't know what is going on with that.

[ospalh]

@hssm: # 2: I see this from time to time. One way i think this can happen is when a learning card (card B) becomes due while you (re)view card A.

[timo-a]

@hssm I found a new way to produce the behaviour in point 2! You don't need new or red-because-wrong-answer cards. open deck get first card correct on second card switch to night mode

[ukanuk]

Just wanted to mention I'm still getting the behavior in point # 2. Generally I leave night mode on, but one of my cards has a stroke order diagram with black lines on a transparent background, which is practically invisible in night mode. Therefore I pull out the navigation drawer, turn off night mode --- and then am presented with different cards. So I end up having night mode disabled for a significant part of the review session, until that offending card reappears in the reviews.

Not a big deal at the end of the day, but it does take a little bit to get back in rhythm of review.

[mikehardy]

Switching to or from night mode causes a full app restart if I recall, yes. So pretty much any ephemeral state (like, current state of the reviewer activity) will be blown away. Not sure how I'd handle that but if there was a way to stuff info in a bundle for the activity and reload it, and someone followed through the control chain on night-mode switches, might be possible.

[mikehardy]

@ukanuk this should be fixed I think along with #5688 via #5693 ? But maybe reviewer needs a change too? Can you check the latest alphas to see if you reproduce

[ukanuk]

@mikehardy The issue is still present when toggling night mode, although I can swap between portrait/landscape on both reviewer and previewer without losing the current card.

This is with version 2.10alpha43, which I got from following directions at https://docs.ankidroid.org/manual.html#betaTesting to join the Google Play beta and also the ankidroidalphatesters google group.

[mikehardy]

@ukanuk sorry it is still happening but thanks a lot for checking that out and letting us know

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[mikehardy]

This is a special case of #3654 - please refer to that issue for easier reproduction than night mode toggles (specifically: "don't keep activities" developer setting in phone preferences

[david-allison]

This is a more complex issue than initially appears.

The issue is that the card is not saved onSaveInstanceState, to work around this, we refresh the next card from the scheduler onCollectionLoaded:

https://github.com/ankidroid/Anki-Android/blob/a316393d837034884fd4ceacef44572111f93ea5/AnkiDroid/src/main/java/com/ichi2/anki/Reviewer.java#L287

In this time, the "next" card from the scheduler may have changed. This causes a different card to be displayed

As for solutions:

1. Save the card id and restore that instead of going through the scheduler ❌
2. Modify the scheduler to add a getCard(id) method ❌
3. Serialize and restore the card to the instance state

1

Not currently feasible. The scheduler makes modifications to the card object inside sched.getCard. This may be only AnkiDroid-related code

2

Not currently feasible. Arbitrary card retrieval not supported by the Rust scheduler: https://github.com/ankitects/anki/blob/main/proto/anki/scheduler.proto#L15

3

• Hard, due to the ties to the collection/android context
• Requires additional non-libAnki methods for serialization
• Workable with the new sched backend (many different parameters saved, but the same concept)
• The best chance that we have

[dae]

That should not be necessary in the v3 scheduler; getQueuedCards() is designed to be idempotent under most circumstances.