IssueTracker

I found some strange pattern. If in Slider I set steps = 10 then BasicMarquee does not work exactly half of the time:

velocity = 0.0.dp, sliderScrollSpeed = 0.0
velocity = 186.18182.dp, sliderScrollSpeed = 0.09090909
velocity = 372.36365.dp, sliderScrollSpeed = 0.18181819// basicMarquee stops working
velocity = 558.5455.dp, sliderScrollSpeed = 0.27272728
velocity = 744.7273.dp, sliderScrollSpeed = 0.36363637// basicMarquee stops working
velocity = 930.9091.dp, sliderScrollSpeed = 0.45454547
velocity = 1117.091.dp, sliderScrollSpeed = 0.54545456// basicMarquee stops working
velocity = 1303.2727.dp, sliderScrollSpeed = 0.6363636
velocity = 1489.4546.dp, sliderScrollSpeed = 0.72727275// basicMarquee stops working
velocity = 1675.6364.dp, sliderScrollSpeed = 0.8181818
velocity = 1861.8182.dp, sliderScrollSpeed = 0.90909094// basicMarquee stops working
velocity = 2048.0.dp, sliderScrollSpeed = 1.0

If earlier I thought that BasicMarquee does not work if you quickly update velocity values, now it seems that BasicMarquee does not work at certain velocity values.

I discovered the exact conditions under which the bug is reproduced. For some reason, if recomposition happens while basicMarquee animation is active, the animation will stop (although the animation should start again from the beginning). And with the next recomposition, the animation will work again.

For example, if you change the number of basicMarquee iterations to 1, you can easily see that after basicMarquee animation ends, the next recomposition starts basicMarquee animation correctly. But if you recompose during basicMarquee animation, the animation will stop until the next recomposition.

Could you recommend some workaround to solve this problem? I'm new to Jetpack Compose and have no idea how to force stop internal animation of basicMarquee before recomposing. Or at least how to get the state of basicMarquee internal animation.

I cannot reproduce this on the 1.6 alpha branch. I suspect it was fixed when migrated to the Modifier.Node API. If you can reproduce on the latest 1.6 alpha, please submit a reproducer project and I'll take another look.

The bug is still there. Reproduced on 1.6.0-alpha06. The bug is also reproduced on the emulator, which means it is not a device-specific bug. I have attached a project with a reproducible bug.

In the demo project I change the velocity of basicMarquee in an infinite loop. It is expected that after each velocity change the animation will start over again, but it "stuck" every second time (when the current scroll animation is active - this is a key part of reproducing the bug).

Minor clarification: source code for basicMarquee modifier is located at androidx.compose.foundation which according to my tests is part of androidx.compose.ui:ui-graphics. At least if I go to implementation in Android Studio it opens the source code of the file C:\Users\Mikhail\.gradle\caches\modules-2\files-2.1\androidx.compose.foundation\foundation-android\1.6.0-alpha06\fe06e22c416549d90173acb7828b3a13f781e8b2\foundation-android-1.6. 0-alpha06-sources.jar!\commonMain\androidx\compose\foundation\BasicMarquee.kt. The version in the path clearly indicates that I am testing the alpha branch. I'll clarify just in case.

I'm pretty sure this is a race condition introduced when I converted basicMarquee to a Modifier.Node.