fix(Android): fix formSheet not adjusting for keyboard when it contains input with autofocus

[kligarski]

Description

Sometimes, formSheet that contains input with autoFocus would not account for the keyboard and would remain behind it. This is because SheetDelegate is set as a OnApplyWindowInsetsListener when fragment is resumed - this happens after finishing formSheet entering animations (animators impact fragment lifecycle). Sometimes, IME insets were applied before this handler was set. Now, we can use WindowInsetsAnimationCallback added in this PR. Its onPrepare method is called before onApplyWindowInsets therefore making it possible to set OnApplyWindowInsetsListener in time.

Changes

• change insetsObserverProxy's listeners to HashSet (we might try to add the same listener multiple times)
• override onPrepare method in WindowInsetsAnimationCallback
• change visibility of SheetDelegate to internal

Test code and steps to reproduce

Open Test2895 screen in the example app, open & close the formSheet (multiple times).

Checklist

• Included code example that can be used to test this change
• Ensured that CI passes

[kkafar]

I see that it improves the situation, however, I'm not convinced taht onPrepare is good palce to do so. My initial impression is that registering observer proxy in onAttachedToWindow would make more sense. Can you check, whether it's feasible timing-wise to do so?

[kligarski]

onAttachedToWindow works as well.

[kkafar]

Answering your question here.

[kligarski]

Decided to comment out this part because it does not work currently (even before this PR, sheet would extend to previous maxHeight) but it causes visual glitch when closing the formSheet.

Before	After
with_newMaxHeight.mp4	without_newMaxHeight.mp4

[kkafar]

I see one issue, however: you say that we can rely on WindowInsetsAnimationCallback. I say: it is supported since API level 30, while min sdk is lower than that. How does the current apporach look on e.g. SDK 29?

[kligarski]

I see one issue, however: you say that we can rely on WindowInsetsAnimationCallback. I say: it is supported since API level 30, while min sdk is lower than that. How does the current apporach look on e.g. SDK 29?

As we're using ViewCompat.setWindowInsetsAnimationCallback to register the callback, it handles the case when using API 21 <= ... < 30 for us.

    static void setCallback(@NonNull View view, @Nullable Callback callback) {
        if (Build.VERSION.SDK_INT >= 30) {
            Impl30.setCallback(view, callback);
        } else if (Build.VERSION.SDK_INT >= 21) {
            Impl21.setCallback(view, callback);
        }
        // Do nothing pre 21
    }

But I now noticed that in the docs, there is a note about using API < 30:

Prior to API 30, if an OnApplyWindowInsetsListener is used on the same view, be sure to always use the ViewCompat version of setOnApplyWindowInsetsListener, otherwise the listener will be overridden by this method.

I'll try to make sure that everything works on API < 30 as well, because we're sometimes overriding onApplyWindowInsets instead of using setOnApplyWindowInsetsListener.

[kligarski]

With setOnApplyWindowInsetsListener, we set the listener on Screen which does not override onApplyWindowInsets so we're good here. I also didn't find any case where we would use View.setOnApplyWindowInsetsListener instead of ViewCompat version on the Screen class. The animation looks on API 29 as good as on 36.

api_29.mov

[kkafar]

Once #2925 (comment) this is answered we can proceed

[kkafar]

Looks good now!