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Thanks! This looks like a bug, thank you for reporting!

Project: platform/frameworks/support
Branch: androidx-main
Author: Jossi Wolf <jossiwolf@google.com>
Link:      https://android-review.googlesource.com/3278651

Update AnchoredDraggable target calculation logic

Update AnchoredDraggable target calculation logic

We were previously relying on currentValue and the next closest anchor in the drag direction, but the simpler and more reliable way is to look at the left and right anchors as the window.

Relnote: Fixed a bug where positional thresholds passed to AnchoredDraggableDefaults.flingBehavior were not considered correctly in some scenarios.
Test: anchoredDraggable_fling_offsetPastHalfwayBetweenAnchors_beforePosThreshold_doesntAdvance
Bug: 367660226
Bug: 366003852
Change-Id: Ifdf0dfcf3d7ff8288affee56e7092bbed473d6ab

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

• androidx.compose.foundation:foundation:1.8.0-alpha04
• androidx.compose.foundation:foundation-android:1.8.0-alpha04
• androidx.compose.foundation:foundation-jvmstubs:1.8.0-alpha04

Using the new version 1.8.0-alpha04 does not seem to resolve the issue for me. I tested with the same setting as the reported issue:

            // it doesn't matter what you put here a the multiplier, the positionalThreshold is always 50%
            positionalThreshold = { d -> d * 0.9f },
            velocityThreshold = { Float.POSITIVE_INFINITY },

Same. I've run this again on 1.8.0-alpha04. When using

positionalThreshold = { d -> d * 0.1f }

Dragging up to 10% or between 50% and 90% will cause it to snap back to the start anchor. Dragging between 10% and 50% or past 90% will cause it to snap to the end anchor.

I would expect It to only return if dragged less than or equal to 10% and snap to the end if dragged greater than 10%.

When using

positionalThreshold = { d -> d * 0.9f }

It acts as if the threshold has been set to 50%.

From what I can tell, nothing has changed about the behavior.

Thanks, we will investigate and update this issue.

Project: platform/frameworks/support
Branch: androidx-main
Author: Jossi Wolf <jossiwolf@google.com>
Link:      https://android-review.googlesource.com/3343747

Update AnchoredDraggable target calculation logic

Update AnchoredDraggable target calculation logic 
 
There was a missed case when the velocity was negative. 
 
Test: New tests with more parameter permutations 
Fixes: 367660226 
Bug: 376931805 
Relnote: "Follow-up fix for an issue in AnchoredDraggable's target calculation where it could settle at the wrong anchor for specific swipes." 
Change-Id: I23b8773d3a694aa3c8de6a8f34b9d7fb54cfe560

What is the fix version?

We will comment on the issue when it has been included in a release. Until then, you can try the snapshot versions from androidx.dev.

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

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

#15, please report a new issue with a full reproduction case and the versions you are using. Thank you!

Running compose foundation 1.8.0-alpha07

I'm using AnchoredDraggable with nested scrolling. When I drag and release the lazy layout sometimes the draggable settles correctly and sometimes it doesn't even when i drag and release past the threshold (positionalThreshold = { distance -> distance / 2f }.

    internal fun nestedScrollConnection(
        dragState: AnchoredDraggableState<Anchors>,
        decayAnimationSpec: DecayAnimationSpec<Float>,
        orientation: Orientation = Orientation.Vertical,
    ): NestedScrollConnection = object : NestedScrollConnection {

        override fun onPreScroll(
            available: Offset,
            source: NestedScrollSource,
        ): Offset {
            val availableDelta = available.toFloat()

            return if (
                availableDelta < 0f
            ) dragState.dispatchRawDelta(availableDelta).toOffset()
            else Offset.Zero
        }

        override fun onPostScroll(
            consumed: Offset,
            available: Offset,
            source: NestedScrollSource,
        ): Offset {
            val availableDelta = available.toFloat()

            return if (
                availableDelta >= 0f
            ) dragState.dispatchRawDelta(availableDelta).toOffset()
            else Offset.Zero
        }

        override suspend fun onPreFling(
            available: Velocity,
        ): Velocity {
            val availableDelta = available.toFloat()

            val consumedOffset = if (availableDelta < 0f) dragState.animateToWithDecay(
                velocity = availableDelta,
                targetValue = Anchors.Collapsed,
                decayAnimationSpec = decayAnimationSpec,
            ) else 0f

            return Velocity(
                x = 0f,
                y = consumedOffset,
            )
        }

        override suspend fun onPostFling(
            consumed: Velocity,
            available: Velocity,
        ): Velocity {
            val availableDelta = available.toFloat()

            if (
                availableDelta > 0f
            ) dragState.animateToWithDecay(
                velocity = availableDelta,
                targetValue = Anchors.Expanded,
                decayAnimationSpec = decayAnimationSpec,
            )

            dragState.settle(animationSpec = spring())

            return Velocity(x = 0f, y = availableDelta)
        }

        private fun Float.toOffset(): Offset = Offset(
            y = if (orientation == Orientation.Vertical) this else 0f,
            x = if (orientation == Orientation.Horizontal) this else 0f,
        )

        @JvmName("offsetToFloat")
        private fun Offset.toFloat() = if (orientation == Orientation.Horizontal) x else y

        @JvmName("velocityToFloat")
        private fun Velocity.toFloat() = if (orientation == Orientation.Horizontal) x else y
    }

Hi, this seems to be a different issue. Please provide a full reproducer in a new issue so we can investigate. Thank you!

Looking at the release notes (https://developer.android.com/jetpack/androidx/releases/compose-foundation) is likely the most straightforward way. Since this issue has a few +1 votes, please keep the comments to the original issue :)

Unfortunately, this still does not work. I'm on 1.8.0-alpha07 and when I use 0.9f from the original example it still snaps at 50%.

#21, are you using exactly the same code shared in #1?

Yes, I'm the OP.

sdkmanager "build-tools;build-tools-version"

Apologies #23, but I am not able to reproduce the issue with the sample from #1, running on Compose 1.8.0-alpha08. Can you please provide a full reproducer project as a zip? Thanks!

Can you please provide any status update / dates if possible?

Hi, the Play store team is working on a feature which could greatly benefit from LazyColumn's addition/deletion animation support. Do you have an updated ETA that you can share with you? Thanks!

Comment #35: Please don't use feature tickets as a place to ask for debugging assistance. If you have a reproducible Compose bug, please file that as a separate bug (and don't use images of code - we can't copy-paste from images).

its almost been 2 years now and even your internal teams at play store are asking for the item addition deletion animations, I was the first to bring this up in this thread first.

Is there any ETA on this ? It was a core functionality with DiffUtils which we shouldnt find workarounds as an implementation for Compose !

Could anyone from Google please share an ETA on this

Hello. We are currently finializing the design for the underlying mechanism we will be using for the disappearance animations. Sorry, we can't give exact estimations, but I can reassure you this feature is in works

bro

I kind of agree with the last poster, if we all "bro" the developers every year or month to bump the thread, they might feel pressured to finish the removal/addition animations. Anyways, hang in there champ, they're probably almost done with that last piece of work

Yesterday was the 4th year open anniversary of this issue lol

It's coming anytime now (probably not in the next 1-2 releases though): https://android-review.googlesource.com/c/platform/frameworks/support/+/2647907

Item appearance and disappearance animation support was added into LazyColumn and LazyRow. Previously it was possible to add Modifier.animateItemPlacement() modifier in order to support placement (reordering) animations. We deprecated this modifier and introduced a new non-experimental modifier called Modifier.animateItem() which allows you to support all three animation types: appearance (fade in), disappearance (fade out) and reordering.

This change is expected to be released as part of 1.7.0-alpha06 release.

Port of this modifier into lazy grids is tracked here: b/330510929

To staggered grids here: b/330511290

Support of other animation types aside of fade in/fade out is tracked here: b/330152398

@comment #51: Please file a separate bug with reproduction steps.

Hello, in the doc, under the heading "Item animations", the last sentence that references this issue should be changed, or removed: https://developer.android.com/develop/ui/compose/lists#item-animations

It still says:

Aside from reorderings, item animations for additions and removals is currently in development. You can track the progress in issue 150812265.

Thank you for letting us know! We've updated the documentation page :)