Predictive back gesture leads to fragments not being initialized/resumed correctly [297379023]

Fixed

Bug

Status Update

No update yet.

Description

pa...@gmail.com

created issue #1

Aug 24, 2023 06:09PM

Component used: Fragment

Version used: 1.7.0-alpha03

Devices/Android versions reproduced on: Pixel 6 with Android 14

The short summary of the issue is that once the predictive back gesture is completed (or started and canceled only), the fragments seem to be stacked on top of each other, with the top one displaying its contents without being interactive and the bottom one handling the touch input, which leads to crashes and unexpected behavior.

I've attached a minimal sample project to reproduce and describe the issues:

Navigate through the app and its two fragments without using the back gesture: everything works as expected.
On the second fragment, use the back gesture to navigate back to the first fragment. Then tap on the overflow menu: the app crashes unexpectedly with an IndexOutOfBoundsException in FragmentManager.
Relaunch the app and on the second fragment, start the back gesture but cancel it. Then tap on the overflow menu of the second fragment: it doesn't react anymore. Move slightly left with the finger and tap again to open the menu: this time it opens and the toast says "First fragment", which means the touch input is handled by the first fragment and contents are displayed by the second one. Now pause the app by moving it to the background, then resume it: the contents are fully gone and the overflow menu of the first fragment can still be opened by tapping on the top right corner (but slightly left of it because the overflow menu of the second fragment seems to cover the first). Using the back gesture will bring you back to the first fragment, which is then again acting as described in step 2.
Repeat step 3 without pausing the app, then tap on the disabled(!) "Go to second fragment" button of the second fragment: the app crashes with an IllegalArgumentException because the touch input is again handled by the first fragment and it's (enabled!) top button, so the executed navigation transaction (first to second fragment with the second currently displayed) is obviously illegal.

Hope you guys can fix that for the next alpha, thanks for your amazing work! :)

test-predictive.zip

115 KB

Download

Comments

il...@google.com <il...@google.com> Aug 24, 2023 06:28PM

Assigned to jb...@google.com.

ap...@google.com <ap...@google.com> #2Aug 31, 2023 02:04AM

Project: platform/frameworks/support
Branch: androidx-main

commit 57ca221882695bd6a52549f4d9ea3b812e6fe87c
Author: Simon Schiller <simonschiller@users.noreply.github.com>
Date: Mon Mar 22 16:09:30 2021

[GH] [FragmentStrictMode] Detect <fragment> tag usage

## Proposed Changes

- Detect `<fragment>` tag usage inside XML layouts

## Testing

Test: See `FragmentStrictModeTest#detectFragmentTagUsage`

## Issues Fixed

Fixes: 153738235

This is an imported pull request from

https://github.com/androidx/androidx/pull/141.

Resolves #141
Github-Pr-Head-Sha: 4ea052596e4341b9f11bcf335e2bc38045a91f19
GitOrigin-RevId: 62e7487aa4874eef6bb556490e193717cf937251
Change-Id: Iae48578e85e4e4897f806d7ade2e2a660adf9479

M fragment/fragment/api/public_plus_experimental_current.txt
M fragment/fragment/api/restricted_current.txt
M fragment/fragment/src/androidTest/java/androidx/fragment/app/strictmode/FragmentStrictModeTest.kt
M fragment/fragment/src/main/java/androidx/fragment/app/FragmentLayoutInflaterFactory.java
M fragment/fragment/src/main/java/androidx/fragment/app/strictmode/FragmentStrictMode.java
A fragment/fragment/src/main/java/androidx/fragment/app/strictmode/FragmentTagUsageViolation.java

https://android-review.googlesource.com/1649748

jb...@google.com <jb...@google.com> #3Sep 5, 2023 03:02PM

Marked as fixed.

This is fixed internally and will be available in the Fragment 1.7.0-alpha04 release.

pr...@google.com <pr...@google.com> #4Sep 6, 2023 07:56PM

The following release(s) address this bug.It is possible this bug has only been partially addressed:

androidx.fragment:fragment:1.7.0-alpha04

pa...@gmail.com <pa...@gmail.com> #5Sep 7, 2023 04:16PM

Thanks Mr Woods! The back gesture now seems to be working, although there are still some remaining issues in alpha04:
When you go to the second fragment in the sample app (with version changed to alpha04 in libs.versions.toml), then the touch targets in the app bar are still covered by some earlier state I think. They are not responding (no ripple and nothing happens), and as soon as you are moving the finger slightly to one side, the touch targets seem to be reached. In my own project with alpha04 the behavior is the same, but multiple taps on the invalid touch target produce an IllegalArgumentException like in alpha03, which I somehow couldn't reproduce with the sample app this time:

java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 0
at jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
at jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
at jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
at java.util.Objects.checkIndex(Objects.java:359)
at java.util.ArrayList.get(ArrayList.java:434)
at androidx.fragment.app.FragmentManager.prepareBackStackState(FragmentManager.java:2478)
at androidx.fragment.app.FragmentManager$PrepareBackStackTransitionState.generateOps(FragmentManager.java:3726)
at androidx.fragment.app.FragmentManager.generateOpsForPendingActions(FragmentManager.java:2256)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1922)
at androidx.fragment.app.FragmentManager.executePendingTransactions(FragmentManager.java:719)
at androidx.fragment.app.FragmentManager.cancelBackStackTransition(FragmentManager.java:989)
at androidx.fragment.app.FragmentManager$1.handleOnBackCancelled(FragmentManager.java:523)
at androidx.activity.OnBackPressedDispatcher.onBackCancelled(OnBackPressedDispatcher.kt:295)
at androidx.activity.OnBackPressedDispatcher.access$onBackCancelled(OnBackPressedDispatcher.kt:63)
at androidx.activity.OnBackPressedDispatcher$4.invoke(OnBackPressedDispatcher.kt:131)
at androidx.activity.OnBackPressedDispatcher$4.invoke(OnBackPressedDispatcher.kt:127)
at androidx.activity.OnBackPressedDispatcher$Api34Impl$createOnBackAnimationCallback$1.onBackCancelled(OnBackPressedDispatcher.kt:396)
at android.window.WindowOnBackInvokedDispatcher$OnBackInvokedCallbackWrapper.lambda$onBackCancelled$3(WindowOnBackInvokedDispatcher.java:353)
at android.window.WindowOnBackInvokedDispatcher$OnBackInvokedCallbackWrapper.$r8$lambda$MvEvoNsuMagpR44wZwrfwOccMBA(Unknown Source:0)
at android.window.WindowOnBackInvokedDispatcher$OnBackInvokedCallbackWrapper$$ExternalSyntheticLambda3.run(Unknown Source:2)
at android.window.BackProgressAnimator$2.onAnimationEnd(BackProgressAnimator.java:144)
at com.android.internal.dynamicanimation.animation.DynamicAnimation.endAnimationInternal(DynamicAnimation.java:720)
at com.android.internal.dynamicanimation.animation.DynamicAnimation.doAnimationFrame(DynamicAnimation.java:690)
at android.animation.AnimationHandler.doAnimationFrame(AnimationHandler.java:328)
at android.animation.AnimationHandler.-$$Nest$mdoAnimationFrame(Unknown Source:0)
at android.animation.AnimationHandler$1.doFrame(AnimationHandler.java:86)

Hope you get this fixed and thank you again!

an...@gmail.com <an...@gmail.com> #6Jun 20, 2024 08:49PM

Hi, I am still seeing this crash in our error logs while using version `androidx.fragment:fragment:1.7.0`, but we can't seem to reproduce the crash. Is this still an open issue?

ho...@myrealtrip.com <ho...@myrealtrip.com> #7Oct 15, 2024 03:10AM

Comment has been deleted.

Message last modified on Oct 15, 2024 03:11AM

ha...@gmail.com <ha...@gmail.com> #8Oct 15, 2024 03:12AM

https://issuetracker.google.com/issues/342316801?pli=1

According to above thread, you should either disable predictive back or upgrade the fragment version to 1.8.3