AnimatedContent moves to targetState before Scaffold composes content [268422136]

Duplicate

of 254645321

Bug

Status Update

No update yet.

Description

jb...@google.com

created issue #1

Feb 9, 2023 03:44AM

This is from https://github.com/google/accompanist/issues/1487:

I haven't been able to reproduce it without a lot of experimental APIs along with Navigation. But essentially given the following:

setContent {
val transition = updateTransition(...)
  transition.AnimatedContent {
    MyComposable()
  }
  if (transition.currentState == transition.targetState) {
    // area #3
  }
}

class MyComposable() {
  // area #1
  Scaffold(
    content = {
      // area #2
    }
  )
}

There are cases where the areas end up being composed in this order: 1, 3, 2 with AnimatedContent completing the transition and then the Scaffold composing its content.

The expectation was that it would always be 1, 2, 3 with the composition of the Scaffold content completing before the callback to area 3.

Is the expectation correct? Or does AnimatedContent completion have some priority over the Scaffold?

This could also be something going on in Scaffold, just wondering what the expectations are here.

Comments

lp...@google.com <lp...@google.com> #2Feb 9, 2023 02:58PM

Nested scrolling works partially (as per

http://b/122818889). Let's discuss if we need full support and if so make sure it works.

lp...@google.com <lp...@google.com> #3Feb 9, 2023 03:45PM

Hi!

What is 'partially' exactly?
How do I see it?
Thanks!

ti...@google.com <ti...@google.com> #4Feb 13, 2023 11:14PM

As of now:
- Nesting scroll views with a scroll direction perpendicular to the ViewPager2's orientation inside ViewPager2 works
- Nesting scroll views with a scroll direction parallel to the ViewPager2's orientation inside ViewPager2 does not work

jb...@google.com <jb...@google.com> #5Feb 14, 2023 12:22AM

Horizontal ViewPager2 not correctly working into a vertical RecyclerView
Set a setNestedScrollingEnabled to the RecyclerView into the ViewPager2 (across reflection) resolves the problem

Illegal State Exception.zip

136 KB

Download

jb...@google.com <jb...@google.com> #6Feb 14, 2023 03:03AM

ageevvalentin@gmail.com, could you provide a sample app? I'd like to learn more about the circumstances that cause the problem; putting a clean ViewPager2 inside a clean RecyclerView seems to work fine, so there must be other factors involved.

ti...@google.com <ti...@google.com> #7Feb 14, 2023 08:11PM

Added a patch for androidx-master-dev that demos a horizontal ViewPager2 inside a vertical RecyclerView.

Verified that it works correctly on a:
- Nexus 4 emulator with API 17
- Nexus 5X emulator with API 28
- Pixel 2 device with API 29

To reproduce:
- Check out the Android Jetpack source (at commit 256899f482ff85cddfb050f37550be7b5ec927ef) (see steps in [1])
- Apply the patch (`git apply 0001-Add-sample-where-a-horizontal-ViewPager2-is-nested-i.patch`)
- Build and install viewpager2's integration-tests app: `./gradlew viewpager2:integration-tests:testapp:installDebug`
- Run it

Closing the issue for now, but please reopen if you have a minimal reproduction app

[1]

https://android.googlesource.com/platform/frameworks/support/+/256899f482ff85cddfb050f37550be7b5ec927ef

ti...@google.com <ti...@google.com> #8Feb 15, 2023 08:01PM

Re-opening as requested by a few users. Narrowed down the focus to nested scrolling elements with the same scroll direction.

jb...@google.com <jb...@google.com> #9Feb 15, 2023 08:04PM

Any progress on this? (only talking about the "same scroll direction" issue)

I searched a lot for workarounds on Google and SO, but it seems no one really found a suitable solution yet.
The thing is that all other VerticalViewPagers out there have other problems that are similarly annoying. Most of them revolve around touch issues like "What's a click and what's a swipe" or "what's the fling threshold to snap to the next page".

So if someone knows of a working sample of VerticalViewPagers, I'd be happy to see a link :)

ti...@google.com <ti...@google.com> #10Feb 15, 2023 09:38PM

Hi, we're unlikely to address the "same scroll direction" issue before 1.0-Stable as it's likely going to require API changes (so v1.1+).

One possible option for VerticalViewPager with nested scrolling in the same scroll direction is using a RecyclerView implementing NestedScrollingParent + PagerSnapHelper to get snapping.
You'd then have to implement the NestedScrollingParent/Child contract between parent/child RecyclerView instances.

ti...@google.com <ti...@google.com> #11Feb 15, 2023 10:33PM

Cool, thanks for this quick answer - Both pieces of information are highly appreciated (rough estimate of tackling this as well as giving hint on how to do it).
I will try implementing what you suggested and in case it is readable code, I will post it here as sample project or somthing similar.

jb...@google.com <jb...@google.com> #12Feb 15, 2023 10:34PM

That'd be great, much appreciated!

ti...@google.com <ti...@google.com> #13Feb 15, 2023 10:39PM

Status: Duplicate of

254645321

So...I was too stupid to understand the back and forth and up and down of NestedScrollingParent and NestedScrollingChild/NestedScrollingChild2 and NestedScrollingParentHelper and NestedScrollingChildHelper
But I figured out another way to achieve the same goal. I attached a demo project with the following setup:

1. A parent RecyclerView with PagerSnapHelper:
This vertical RecyclerView has two items/pages.
The upper page is just a simple TextView.
The lower page contains the nested RecyclerView.
Both pages are Fragments if that is of any concern.

2. A PagingLinearLayoutManager:
This is a LinearLayoutManager with the capability to enable/disable scrolling.
It is used for the parent RecyclerView.

3. A OnItemTouchListener:
This is also used for the parent RecyclerView.
It saved the initial y coordinate on ACTION_DOWN
During ACTION_MOVE event, it decides whether the PagingLinearLayoutManager is allowed to scroll (i.e. to switch between pages)

The important parts of the code are commented. Hope this helps someone else!

mo...@gmail.com <mo...@gmail.com> #14May 31, 2023 10:20AM

Comment has been deleted.

Message last modified on May 31, 2023 10:21AM

ap...@google.com <ap...@google.com> #15Aug 10, 2023 08:23PM

There is a hook for this

https://medium.com/@al.e.shevelev/how-to-reduce-scroll-sensitivity-of-viewpager2-widget-87797ad02414

na...@google.com <na...@google.com> #16Jan 24, 2024 07:53PM

I'm a bit skeptical about the suggested solution from

comment#15

that modifies the touch slop.

We're working on a solution that'll work reliably with ViewPager2 1.0. See

https://r.android.com/1131083.
Not finalized at the time of writing, but might help some people already. Notice NestedScrollableHostLayout wrapping [1] a scrollable child.

[1]

https://r.android.com/c/platform/frameworks/support/+/1131083/4/viewpager2/integration-tests/testapp/src/main/res/layout/item_horizontal_rvs.xml#55

pa...@gmail.com <pa...@gmail.com> #17Apr 4, 2024 09:58PM

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

commit 1316417bc87741ea9f739a453eb9e792512c9651
Author: Jelle Fresen <jellefresen@google.com>
Date: Tue Oct 01 16:58:57 2019

Add sample of nested scrolling in ViewPager2

This shows how nested scrolling can be achieved in ViewPager2. Every
child on a page that scrolls in the same direction as ViewPager2 must be
wrapped by a NestedScrollableHostLayout, and one must make sure that the
scrollable child implements canScrollHorizontally/Vertically in order
for this to work.

Bug: 123006042
Test: Manual, run ViewPager2 demo app
Change-Id: I79e24b7668cf7ff5c05c350ea3ab9134dd74b3a4

M viewpager2/integration-tests/testapp/src/main/AndroidManifest.xml
M viewpager2/integration-tests/testapp/src/main/java/androidx/viewpager2/integration/testapp/BrowseActivity.kt
A viewpager2/integration-tests/testapp/src/main/java/androidx/viewpager2/integration/testapp/NestedScrollableHost.kt
A viewpager2/integration-tests/testapp/src/main/java/androidx/viewpager2/integration/testapp/ParallelNestedScrollingActivity.kt
A viewpager2/integration-tests/testapp/src/main/res/layout/item_nested_recyclerviews.xml
M viewpager2/integration-tests/testapp/src/main/res/values/colors.xml
M viewpager2/integration-tests/testapp/src/main/res/values/strings.xml

https://android-review.googlesource.com/1131083

https://goto.google.com/android-sha1/1316417bc87741ea9f739a453eb9e792512c9651

NavigationLibSample.zip

109 KB