Is `SharedTransitionLayout` currently not usable w...

# compose-desktop

[Marcin Wisniowski]

Is SharedTransitionLayout currently not usable with LazyColumn?
After putting much work getting the animations to work perfectly, the LazyColumn now often crashes when scrolled.
https://issuetracker.google.com/issues/336140982
Bug is marked as fixed, but that version of Compose is not released for Desktop use, and someone already commented it isn't fixed anyway.

[Doris Liu]

Are you using LazyColumn or LazyGrid?

[Marcin Wisniowski]

Both, the shared transition switches between the two. But the crash happens in the LazyColumn. Even if I only leave the LazyColumn in, and remove the shared element transition on the children, it still crashes when scrolling, just because the LazyColumn is inside a SharedTransitionLayout.

[Marcin Wisniowski]

All right, the crash only happens if you use movableContentOf in the children of the LazyColumn that is in a SharedTransitionLayout. I removed movableContentOf from my list items and the crashing is gone.

[Doris Liu]

If you could provide a minimal repro with the movableContentOf and LazyColumn combo, and steps to trigger crash, I can help verify if the fix from the issue above fixes this crash using 1.8.0-alpha01.

[Doris Liu]

Also note, the issue with LazyColumn should be fixed per confirmation from dev. The crash in LazyGrids is due to incomplete support for lookahead, which we're currently prioritizing addressing

[Marcin Wisniowski]

@Doris Liu
I managed to create a minimal repro. It crashes quickly without user interaction.

@OptIn(ExperimentalSharedTransitionApi::class)
fun main() {
    singleWindowApplication {
        var items by remember { mutableStateOf(List(500) { it }) }

        LaunchedEffect(Unit) {
            while (true) {
                delay(10)
                items = items.shuffled()
            }
        }

        SharedTransitionLayout {
            LazyColumn {
                items(items, key = { it }) {
                    val movableContent = remember { movableContentOf { Text("Item $it") } }
                    Box(Modifier.animateItem()) {
                        Box {
                            movableContent()
                        }
                    }
                }
            }
        }
    }
}

[Doris Liu]

Thank you. Could you also share the stack trace? I'm seeing a different crash: java.lang.IllegalArgumentException: measure is called on a deactivated node as I tried it out locally.

[Marcin Wisniowski]

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Error: Placement happened before lookahead.
	at androidx.compose.ui.internal.InlineClassHelperKt.throwIllegalStateException(InlineClassHelper.kt:26)
	at androidx.compose.ui.node.LayoutNodeLayoutDelegate$MeasurePassDelegate.placeSelf-MLgxB_4(LayoutNodeLayoutDelegate.kt:2105)
	at androidx.compose.ui.node.LayoutNodeLayoutDelegate$MeasurePassDelegate.placeAt-f8xVGno(LayoutNodeLayoutDelegate.kt:767)
	at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:35)
	at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:621)
	at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50$default(Placeable.kt:259)

[Doris Liu]

This is what I see:

Process: androidx.compose.animation.demos.test, PID: 32685
                                                                                                    java.lang.IllegalArgumentException: measure is called on a deactivated node
                                                                                                    	at androidx.compose.ui.internal.InlineClassHelperKt.throwIllegalArgumentException(InlineClassHelper.kt:34)
                                                                                                    	at androidx.compose.ui.node.LayoutNodeLayoutDelegate$MeasurePassDelegate.remeasure-BRTryo0(LayoutNodeLayoutDelegate.kt:2071)
                                                                                                    	at androidx.compose.ui.node.LayoutNodeLayoutDelegate$MeasurePassDelegate.measure-BRTryo0(LayoutNodeLayoutDelegate.kt:668)
                                                                                                    	at androidx.compose.foundation.lazy.layout.LazyLayoutMeasureScopeImpl.measure-0kLqBqw(LazyLayoutMeasureScope.kt:125)
                                                                                                    	at androidx.compose.foundation.lazy.LazyListMeasuredItemProvider.getAndMeasure-0kLqBqw(LazyListMeasuredItemProvider.kt:55)
                                                                                                    	at androidx.compose.foundation.lazy.LazyListMeasuredItemProvider.getAndMeasure--hBUhpc(LazyListMeasuredItemProvider.kt:43)
                                                                                                    	at androidx.compose.foundation.lazy.LazyListMeasuredItemProvider.getAndMeasure--hBUhpc(LazyListMeasuredItemProvider.kt:28)
                                                                                                    	at androidx.compose.foundation.lazy.layout.LazyLayoutItemAnimator.onMeasured(LazyLayoutItemAnimator.kt:255)
                                                                                                    	at androidx.compose.foundation.lazy.LazyListMeasureKt.measureLazyList-LCrQqZ4(LazyListMeasure.kt:366)
                                                                                                    	at androidx.compose.foundation.lazy.LazyListKt$rememberLazyListMeasurePolicy$1$1.invoke-0kLqBqw(LazyList.kt:350)
                                                                                                    	at androidx.compose.foundation.lazy.LazyListKt$rememberLazyListMeasurePolicy$1$1.invoke(LazyList.kt:198)
                                                                                                    	at androidx.compose.foundation.lazy.layout.LazyLayoutKt$LazyLayout$1$2$1.invoke-0kLqBqw(LazyLayout.kt:78)
                                                                                                    	at androidx.compose.foundation.lazy.layout.LazyLayoutKt$LazyLayout$1$2$1.invoke(LazyLayout.kt:76)
                                                                                                    	at androidx.compose.ui.layout.LayoutNodeSubcompositionsState$createMeasurePolicy$1.measure-3p2s80s(SubcomposeLayout.kt:730)
                                                                                                    	at androidx.compose.ui.node.InnerNodeCoordinator.measure-BRTryo0(InnerNodeCoordinator.kt:127)

[Marcin Wisniowski]

Possibly you are on a different version, and it's fixed on yours but not completely and crashes somewhere else?

[Marcin Wisniowski]

I'm on 1.7.0-beta02 now of JetBrains Compose

[Doris Liu]

I'm trying it on 1.8.0-alpha01 androidx compose, which contains the fix of the issue that you linked

[Doris Liu]

I reduced your repro snippet further.
Some initial investigation has revealed that there is some inconsistency between what node SubcomposeLayout considers ready to be reused and what was actually deactivated. Will need more investigation to figure out what's causing that. Until then, you could track it at: https://issuetracker.google.com/368429360

[Marcin Wisniowski]

Thank you. 👍 Though now I wonder why removing movableContentOf from my application fixed the crashing, if it isn't what triggers this issue after all.

[Marcin Wisniowski]

Small update: removing movableContentOf only apparently resolved this issue for me. Although it doesn't crash almost immediately now, it still crashes – just very rarely. I'm removing the SharedTransitionLayout for now and hopefully I can add it back at some point.

[Doris Liu]

That's unfortunate. 😞 Good news is your repro helped us narrow down two issues in two different components, and the fixes are in review. Once they are released, you should be able to get back to using shared elements.

[Marcin Wisniowski]

@Doris Liu I have now updated to Compose Multiplatform 1.7.3, which is based on Foundation 1.7.6. The issue tracker says the fix is in foundation:1.7.4, so my understanding is that I should have the fix now. But my reproducer above still crashes – it just takes a minute or two of letting it run now, instead of crashing almost immediately. Is there more to this issue?

[Marcin Wisniowski]

For anyone finding this, I commented under the issue that it's still happening: https://issuetracker.google.com/issues/368429360#comment34

[Marcin Wisniowski]

New issue: https://issuetracker.google.com/issues/396334726

[Doris Liu]

Thanks for the update. We found other code paths that led to the same issue, and landed the fix in 1.8. Please see: https://issuetracker.google.com/336140982

[Marcin Wisniowski]

Thank you, can confirm it's fixed in org.jetbrains.compose:1.8.0-alpha03, which uses 1.8.0-beta01 of Jetpack Compose.