IssueTracker

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

if (constraintsExceedsCertainThreshold) composeSomeContent() else someOtherContent()

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?

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?

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.

Hey, sorry to insist - any more ideas here?

I'm investigating what would cause items to be composed but not placed.

We'll submit a fix in shared element in 1.8 to account for that scenario if that's an intended behavior.

Have you tried a recent 1.8 release and see if it's reproducible?

Thank you!

Unfortunately we cannot release publicly with 1.8 alpha, and we never reproed this issue locally even with 1.7.x.

I'll prepare a fix to account for the use case where content may be composed but never participate in either measurement or placement. Keep in mind, the fix likely will only land in 1.8.

Awesome, thank you! If there's any chance to have it in 1.7.6, would be absolutely amazing, but no worries if not. Thanks a lot again for the help!

Project: platform/frameworks/support
Branch: androidx-main
Author: Doris Liu <tianliu@google.com>
Link:      https://android-review.googlesource.com/3349070

Require shared element to draw in place before drawing in overlay

Require shared element to draw in place before drawing in overlay 
 
This change fixes a rare issue where a shared element is composed 
in both incoming and outgoing content, but measured and placed in 
neither. The fix involves checking the shared element has been 
drawn for at least frame before drawing it in the overlay. This 
accounts for not only the requirement to measure and place shared 
elements, but also ensured that when the draw is skipped by 
a parent, shared element will not draw. 
 
Fixes: 371802474 
Test: New test added 
Change-Id: I35108ce255cf4728a9ca3ef7834d6962abcc94c0

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

• androidx.compose.animation:animation:1.8.0-alpha07
• androidx.compose.animation:animation-android:1.8.0-alpha07
• androidx.compose.animation:animation-jvmstubs:1.8.0-alpha07
• androidx.compose.animation:animation-linuxx64stubs:1.8.0-alpha07