Allow pinning some of the lazy list items [259274257]

Fixed

Feature Request

Status Update

No update yet.

Description

an...@google.com

created issue #1

Nov 15, 2022 07:00PM

We need to provide an api (internal for now as the usage is in foundation) which allows to
1) Via composition local to find a parent pinnable parent
2) Call pin on it, which means that this composable will be kept composed even if it will naturally be scrolled our of the viewport of this pinnable parent
3) To be defined if we need to place such layoutnode or not. Probably we should, we can try to first pin it at some fake position outside the viewbounds
4) There should be a possibility to unpin it when the pinning is not needed anymore (for example the item is not focused anymore)
5) Such logic should work for nested lazy lists recursively, for example for cases when we have focused item inside LazyRow inside LazyColumn
6) Eventually the code should be abstracted away so it is easy to add such logic into your own LazyLayout implementation, for the first implementation we can just add it in LazyColumn as an internal api

Comments

st...@google.com <st...@google.com> Nov 18, 2022 11:38AM

Accepted by an...@google.com.

lo...@gmail.com <lo...@gmail.com> #2Dec 6, 2022 02:53PM

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

commit c60f33e229e31ab328ef6b59dab63b264954831c
Author: Alexandre Elias <aelias@google.com>
Date: Fri Jul 10 16:23:09 2020

Semantics no-op cleanups

Partly in response to lmr's broad code review, I did a pass of
superficial API/implementation cleanup. The main changes are:

- I changed each Boolean SemanticsProperty where false is equivalent to
not being present to take "Unit" instead. This is conceptually
clearer: it avoids questions like "can I cancel out a semantics from a
merged child by setting it to false?" Because "property = Unit" looks
weird, I also changed the style of these to "property()".

- I moved the Semantics id generator closer to where it's used, in
SemanticsModifierCore. I made it internal and an AtomicInt.
(Note that integer ids are heavily used in the Android
AccessibilityNodeInfo APIs so I can't simply remove them entirely.)

- I deleted dead code. Some examples include SemanticsHintOverrides,
a public API not connected to anything, and SemanticsPropertyKey
merge() open method which is never called. (In both cases I have
a different plan in mind for accessibility.)

Fixes: 145951226
Fixes: 145955412
Test: existing tests
Relnote: "Single-value semantics properties now use a calling style.
For example, 'semantics { hidden = true }' is now written as:
'semantics { hidden() }'."

Change-Id: Ic1afd12ea22c926babc9662f1804d80b33aa0cfc

M ui/integration-tests/benchmark/src/androidTest/java/androidx/ui/benchmark/test/LayoutNodeModifierBenchmark.kt
M ui/ui-core/api/0.1.0-dev15.txt
M ui/ui-core/api/current.txt
M ui/ui-core/api/public_plus_experimental_0.1.0-dev15.txt
M ui/ui-core/api/public_plus_experimental_current.txt
M ui/ui-core/api/restricted_0.1.0-dev15.txt
M ui/ui-core/api/restricted_current.txt
M ui/ui-core/src/androidAndroidTest/kotlin/androidx/ui/graphics/vector/VectorTest.kt
M ui/ui-core/src/androidAndroidTest/kotlin/androidx/ui/semantics/SemanticsTests.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidActuals.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidComposeView.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidComposeViewAccessibilityDelegateCompat.kt
M ui/ui-core/src/androidMain/kotlin/androidx/ui/core/AndroidPopup.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/Expect.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsConfiguration.kt
D ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsHintOverrides.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsModifier.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsNode.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsOwner.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/core/semantics/SemanticsWrapper.kt
M ui/ui-core/src/commonMain/kotlin/androidx/ui/semantics/SemanticsProperties.kt
M ui/ui-foundation/api/0.1.0-dev15.txt
M ui/ui-foundation/api/current.txt
M ui/ui-foundation/api/public_plus_experimental_0.1.0-dev15.txt
M ui/ui-foundation/api/public_plus_experimental_current.txt
M ui/ui-foundation/api/restricted_0.1.0-dev15.txt
M ui/ui-foundation/api/restricted_current.txt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/Clickable.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/Dialog.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/Scroller.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/selection/Selectable.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/selection/Toggleable.kt
M ui/ui-foundation/src/main/java/androidx/ui/foundation/semantics/FoundationSemanticsProperties.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/ButtonTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/CardTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/CheckboxScreenshotTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/RadioButtonScreenshotTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/ScaffoldTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/SnackbarTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/SurfaceTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/ripple/RippleIndicationTest.kt
M ui/ui-material/src/androidTest/java/androidx/ui/material/textfield/TextFieldScreenshotTest.kt
M ui/ui-material/src/main/java/androidx/ui/material/AppBar.kt
M ui/ui-material/src/main/java/androidx/ui/material/TextFieldImpl.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/AssertsTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/CallSemanticsActionTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/ErrorMessagesTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/FindersTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/PrintToStringTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/ScrollToTest.kt
M ui/ui-test/src/androidTest/java/androidx/ui/test/TextActionsTest.kt
M ui/ui-test/src/main/java/androidx/ui/test/Actions.kt
M ui/ui-test/src/main/java/androidx/ui/test/Filters.kt
M ui/ui-text/api/0.1.0-dev15.txt
M ui/ui-text/api/current.txt
M ui/ui-text/api/public_plus_experimental_0.1.0-dev15.txt
M ui/ui-text/api/public_plus_experimental_current.txt
M ui/ui-text/api/restricted_0.1.0-dev15.txt
M ui/ui-text/api/restricted_current.txt
M ui/ui-text/src/commonMain/kotlin/androidx/ui/text/CoreTextField.kt
M ui/ui-text/src/commonMain/kotlin/androidx/ui/text/TextSemanticsProperties.kt

https://android-review.googlesource.com/1360099

an...@google.com <an...@google.com> #3Dec 6, 2022 02:59PM

You mean you don't want such items to be disposed when they are not visible anymore as recreating them will be expensive?

lo...@gmail.com <lo...@gmail.com> #4Dec 6, 2022 03:45PM

Yes, that's what I mean.

an...@google.com <an...@google.com> #5Dec 6, 2022 03:47PM

It is not really a recommended approach, instead we are trying to make reusing to be more efficient. Is it about AndroidView being used as an item? However theoretically the api we are planning to expose will allow such use cases

lo...@gmail.com <lo...@gmail.com> #6Dec 6, 2022 04:05PM

Yes and no. Could also be a lot of Flow activation when the composable is first composed.

ap...@google.com <ap...@google.com> #7Dec 8, 2022 04:27PM

Marked as fixed.

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

commit 36abe1718e16025253df6f22cd786fc034447be5
Author: Andrey Kulikov <andreykulikov@google.com>
Date: Wed Nov 16 19:27:22 2022

Add items pinning functionality to the lazy lists

Lazy lists now provide an instance of PinnableContainer via LocalPinnableContainer for each item. It allows to pin the current item from inside the content of the item. Pinning means we will continue composing, measuring and placing this item even when it is scrolled away from the view. Note that the placed position is not guaranteed to be the real one as we do not compose the items in between the pinned one and the first/last visible one.
This interface was added to the ui module as conceptually PinnableContainer is decoupled from lazy layouts from the foundation module. Other layouts using SubcomposeLayout could have some similar functionality and may want to support pinning. And it will allow for modifiers from ui to use this interface to pin their content.

Test: LazyListPinnableContentTest
Fixes: 259274257
Fixes: 195049010
Relnote: Introduced PinnableContainer api propagated by lazy lists via a composition local which allows to pin current item. This means such item will not be disposed when it is scrolled away from the view. For example, Modifier.focusable() will pin the current focused item via this mechanism.
Change-Id: Ib8881191a529c9d9dc5e886570650b1987763207

M compose/foundation/foundation/api/current.ignore
M compose/foundation/foundation/api/current.txt
M compose/foundation/foundation/api/public_plus_experimental_current.txt
M compose/foundation/foundation/api/restricted_current.ignore
M compose/foundation/foundation/api/restricted_current.txt
M compose/foundation/foundation/src/androidAndroidTest/kotlin/androidx/compose/foundation/FocusableTest.kt
D compose/foundation/foundation/src/androidAndroidTest/kotlin/androidx/compose/foundation/lazy/layout/PinnableParentTest.kt
M compose/foundation/foundation/src/androidAndroidTest/kotlin/androidx/compose/foundation/lazy/list/LazyListBeyondBoundsItemCountTest.kt
A compose/foundation/foundation/src/androidAndroidTest/kotlin/androidx/compose/foundation/lazy/list/LazyListPinnableContainerTest.kt
D compose/foundation/foundation/src/androidAndroidTest/kotlin/androidx/compose/foundation/lazy/list/LazyListPinningTest.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/Focusable.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/LazyList.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/LazyListItemProvider.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/LazyListMeasure.kt
A compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/LazyListPinnableContainerProvider.kt
D compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/LazyListPinningModifier.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/LazyListState.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/grid/LazyGridItemProvider.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/layout/LazyLayoutItemProvider.kt
D compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/layout/PinnableParent.kt
M compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/lazy/staggeredgrid/LazyStaggeredGridItemProvider.kt
M compose/ui/ui/api/current.txt
M compose/ui/ui/api/public_plus_experimental_current.txt
M compose/ui/ui/api/restricted_current.txt
A compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/layout/PinnableContainer.kt
M tv/tv-foundation/api/current.txt
M tv/tv-foundation/api/public_plus_experimental_current.txt
M tv/tv-foundation/api/restricted_current.txt
A tv/tv-foundation/src/androidTest/java/androidx/tv/foundation/lazy/list/LazyListPinnableContainerTest.kt
D tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/LazyListPinningModifier.kt
M tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/grid/LazyGridItemProvider.kt
M tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/list/LazyBeyondBoundsModifier.kt
M tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/list/LazyList.kt
M tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/list/LazyListBeyondBoundsInfo.kt
M tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/list/LazyListItemProvider.kt
M tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/list/LazyListMeasure.kt
A tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/list/LazyListPinnableContainerProvider.kt
M tv/tv-foundation/src/main/java/androidx/tv/foundation/lazy/list/LazyListState.kt

https://android-review.googlesource.com/2304138

na...@google.com <na...@google.com> #8Jan 11, 2023 08:11PM

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

androidx.compose.foundation:foundation:1.4.0-alpha04
androidx.compose.ui:ui:1.4.0-alpha04

ch...@gmail.com <ch...@gmail.com> #9Jan 13, 2023 07:58AM

could you please provide example on how to properly pin and AndroidView using LocalPinnableContainer?

an...@google.com <an...@google.com> #10Jan 13, 2023 01:06PM

Hello. What use case are you trying to solve?

ch...@gmail.com <ch...@gmail.com> #11Jan 13, 2023 02:48PM

in LazyColumn i have couple of AndroidView (WebView) items. Currently they gets destroyed when items are scrolled away. Next time they get recreated and WebView will load url again.

I guess now with LocalPinnableContainer it's possible to retain those items?

an...@google.com <an...@google.com> #12Jan 13, 2023 02:57PM

Even that you can try to hack it to help your use case, officially we are not recommending doing so. We hope that

b/230099236

we are currently investigating should help such use cases

ch...@gmail.com <ch...@gmail.com> #13Jan 13, 2023 04:56PM

Thanks for letting know that this isn't recommended approach.

What would be good usecase for LocalPinnableContainer?

an...@google.com <an...@google.com> #14Jan 13, 2023 04:58PM

Two use cases we are currently planning to use it for are keeping an item active when it is focused, or when text selection is including this item

pr...@google.com <pr...@google.com> #15Feb 8, 2023 06:21PM