LazyColumnFor does not scroll smoothly as ScrollableColumn [168293643]

Fixed

Bug

Status Update

No update yet.

Description

gs...@gmail.com

created issue #1

Sep 12, 2020 01:39PM

Android Studio Build: Android Studio Canary 9
Version of Gradle Plugin: gradle:4.2.0-alpha09
OS: Android 9

Compose version : 1.0.0-alpha02
Kotlin compiler: 1.4.0

Problem

When I use LazyColumnFor and try to drag all the list to the end or do a fast drag between items it seems like its choppy and not smooth, if I drag till the end it will glitch on the last item

Example

@Composable
fun RecipeColumnListDemo(recipeList:List<Recipe>){
LazyColumnFor(items = recipeList) { item ->
RecipeCard(recipe = item)
}
}

where RecipeCard(recipe) loads images sincronously

@Composable
private fun RecipeCard(recipe: Recipe){
val image = imageResource(R.drawable.header)
Surface(shape = RoundedCornerShape(8.dp),elevation = 8.dp,modifier = Modifier.padding(8.dp)) {
Column(modifier = Modifier.padding(16.dp)) {
val imageModifier = Modifier.preferredHeight(150.dp).fillMaxWidth().clip(shape = RoundedCornerShape(8.dp))
Image(asset = image,modifier = imageModifier,contentScale = ContentScale.Crop)
Spacer(modifier = Modifier.preferredHeight(16.dp))
Text(text = recipe.title,style = typography.h6)
for(ingredient in recipe.ingredients){
Text(text = "* $ingredient",style = typography.body2)
}
}
}
}

I have also changed the way I load images with loadImageResource, but its also not a smooth scroll when I fast drag to the end of the list

Is this issue on my side ?

I have tried JetChat and it uses a ScrollableColumn which the scrolling is smoother than the the LazyColumnFor

Video:

https://drive.google.com/file/d/1RniEokUmaVlehvMBRNjMPZS9AgIXkVZI/view?usp=sharing

Comments

gs...@gmail.com <gs...@gmail.com> #2Sep 12, 2020 03:59PM

Hi. Thanks for reporting this. Fixed in this changelist. This should be available in alpha-04

cl...@google.com <cl...@google.com> Sep 14, 2020 09:25AM

Assigned to an...@google.com.

an...@google.com <an...@google.com> #3Sep 14, 2020 01:19PM

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

commit e782987543a9f8ccd485e970ddc74564b24378db
Author: Vighnesh Raut <vighnesh.raut13@gmail.com>
Date: Mon Jan 02 15:27:40 2023

fix: tab row crashes when only 1 tab is added

Bug:

b/264018028

Test: Added unit test

Change-Id: I6381dbac304fc1d69d3708c6655f8b595668e93f

M tv/tv-material/src/androidTest/java/androidx/tv/material/TabRowTest.kt
M tv/tv-material/src/main/java/androidx/tv/material/TabRow.kt

https://android-review.googlesource.com/2373449

gs...@gmail.com <gs...@gmail.com> #4Sep 14, 2020 01:30PM

deleted

ap...@google.com <ap...@google.com> #5Sep 23, 2020 11:17AM

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

androidx.tv:tv-material:1.0.0-alpha04

ap...@google.com <ap...@google.com> #6Oct 6, 2020 12:21PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit dc602125a9e5fc15a37ba4fa7610998a94ead29f
Author: Andrey Kulikov <andreykulikov@google.com>
Date: Fri Sep 25 21:14:09 2020

Do less work in SubcomposeLayout when subcompose called with the same lambda

If the lambda object for the slot didn't change and there were no pending recompositons we can skip the whole subcompositions invocation as it will result in unchanged tree. Starting subcomposition is a heavy weight operation so this change allows to improve the measure benchmarks for LazyColumn scrolling by 88 percents.
To achieve it I added a hasPendingChanges() method for Composition class.

Bug: 168293643
Bug: 167972292
Bug: 165028371
Relnote: The scrolling performance of LazyColumn/Row is improved by doing less work in subcomposition on every scroll. The new hasInvalidations() method was added for Composition class. hasPendingChanges() method from Recomposer was renamed to hasInvalidations()
Test: This is not changing the behavior so I can't cover it with a unit test, but it dramatically improves the benchmark. So if this optimization will stop working in the future we will get a regression.
Change-Id: Ib2f324dd6845fd83321e0d4f3fa6e502c346dbc3

M compose/runtime/runtime/api/current.txt
M compose/runtime/runtime/api/public_plus_experimental_current.txt
M compose/runtime/runtime/api/restricted_current.txt
M compose/runtime/runtime/src/androidAndroidTest/kotlin/androidx/compose/runtime/AmbientTests.kt
M compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/Composition.kt
M compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/Recomposer.kt
M compose/test-utils/src/androidMain/kotlin/androidx/compose/testutils/AndroidComposeTestCaseRunner.kt
M compose/ui/ui/src/androidMain/kotlin/androidx/compose/ui/platform/ComposeView.kt
M compose/ui/ui/src/androidMain/kotlin/androidx/compose/ui/platform/Wrapper.kt
M compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/layout/SubcomposeLayout.kt
M ui/ui-test/src/androidMain/kotlin/androidx/ui/test/android/ComposeIdlingResource.kt
M ui/ui-test/src/androidMain/kotlin/androidx/ui/test/android/CompositionAwaiter.kt
M ui/ui-test/src/desktopMain/kotlin/androidx/ui/test/DesktopComposeTestRule.kt

https://android-review.googlesource.com/1439054

an...@google.com <an...@google.com> #7Oct 7, 2020 02:06PM

Marked as fixed.

There is one optimization for LazyColumn scrolling has been merged in alpha04 and another is upcoming in alpha05.

I will close the bug as fixed for now, Please feel free to comment again if after migrating to alpha05 and starting using loadImageResource for an item the scrolling performance is still unacceptable. Thanks!

al...@mercari.com <al...@mercari.com> #8Oct 20, 2020 01:12PM

Thanks for your efforts improving the performance of the lazy lists! I was able to observe some improvements.

However it's still slow from my testing on alpha05. I tried removing the image loading (which I was loading with Glide) and just replaced them with Box(Modifier.background(DsToken.colors.backgroundSecondary) and the )(slow) performance is around the same for the initial scroll.

It seems, when all items have been rendered, it starts to scroll smoothly. So I supposed there's something slow with the initial composition for each of the lazy item. Before, the scrolling was just slow throughout the whole app session.

Message last modified on Oct 20, 2020 01:14PM

an...@google.com <an...@google.com> #9Oct 20, 2020 01:21PM

yes, the composition itself is still quite slow. so we do pretty much a lot of work every time we need to compose a new item.
maybe if you can create a working repro sample app which I can check out and debug more?