NavHostFragment crashes when a custom DialogNavigator is used [175979140]

Fixed

Bug

Status Update

No update yet.

Description

ru...@gmail.com

created issue #1

Dec 20, 2020 09:20PM

Component used: Navigation
Version used: 2.3.2

Caused by:
- NavHostFragment looks up a DialogFragmentNavigator in "onAttachFragment" and no null check is done
- A custom Dialog fragment navigator can't extend from DialogFragmentNavigator as it's a final class

Commit that introduced this:

https://android.googlesource.com/platform/frameworks/support/+/2674709cf3f9d2d46c9bcee55ec01eb115143aaa

Can the new API be used instead to fix this issue in the next alpha/beta release?
In alternative, do you suggest other workaround or should we wait and stay in 2.3.1 until this is fixed?

Comments

il...@google.com <il...@google.com> #2Dec 23, 2020 11:57PM

Still crashing with Compose 1.7.4.
I also tried moving sharedElement to BoxWithConstraints (rather than in its content), but did not help.
So the layout hierarchy looks like this (with more details and with "..." I replaced series of "normal" layouts):
NavHost -> ... -> AnimatedVisibility -> ... -> BoxWithConstraints with sharedElement -> some content
\> ... -> AnimatedVisibility -> ... -> LazyList -> ... -> Animated Visibility -> Selection container -> BoxWithConstraints with sharedElement -> some content

Any ideas?

ru...@gmail.com <ru...@gmail.com> #3Dec 28, 2020 06:55PM

In your BoxWithConstraints do you do any conditional composition? Things like:

if (constraintsExceedsCertainThreshold) composeSomeContent() else someOtherContent()

ru...@gmail.com <ru...@gmail.com> #4Jan 5, 2021 05:09PM

No, it's just a `Text` which has different style depending on constraints.
Also note `sharedElement` is put on `BoxWithContraints` now, not on the content.
Thanks!

ru...@gmail.com <ru...@gmail.com> #5Feb 8, 2021 11:04PM

Based on the stacktrace, it seems like the item in question is composed but never placed. Do you use custom precompose or prefetch logic in your lazy list?

il...@google.com <il...@google.com> Apr 6, 2021 07:45PM

Assigned to il...@google.com.

ap...@google.com <ap...@google.com> #6Apr 7, 2021 04:10PM

No, nothing custom. Just the default prefetch logic.
There is also one `AnimatedContent` above the `BoxWithConstraints`. Could this cause issues?
Thank you for looking into this.

il...@google.com <il...@google.com> #7Apr 7, 2021 05:31PM

Marked as fixed.

The AnimatedContent never skips measuring/placing children after it composes them. So I don't expect that to be the issue.

Since you mentioned the modifier is on BoxWithConstraints rather than on the children of BoxWithConstraints, my guess is it's most likely related to LazyList.

Can you clarify what type of LazyList you are using? Is it LazyColumn/Row or LazyGrid, or something else?

ru...@gmail.com <ru...@gmail.com> #8Apr 7, 2021 05:49PM

Makes sense, thanks.
It's a LazyColumn.

il...@google.com <il...@google.com> #9Apr 7, 2021 05:54PM

One interesting observation is that this stack trace did not seem to come from the ComposeView with our app's Activity content. Because I did a release with copy pasted setContent + ComposeView subclass that is catching exceptions in dispatchDraw and it did not catch this crash. Is the animations framework doing content composition outside the app's composition context? One note: at the time I tried this exception catching, sharedElement was applied to the content of BoxWithConstraints (rather than to the BoxWithConstraints itself), but I don't think this would have caused the exception catching not to work.