BackHandler crashes in IDE preview [185693006]

Fixed

Bug

Status Update

No update yet.

Description

za...@gmail.com

created issue #1

Apr 19, 2021 03:01AM

Jetpack Compose release version: 1.0.0-beta04
Android Studio Build: 7.0.0-alpha14

Steps to Reproduce:

Create a composable containing a BackHandler composable.
Try to render the composable in the IDE preview with an @Preview composable.

The preview will throw an exception about there not being any BackDispatcher available.

Because there isn't any back button in the IDE preview, and most previewed composables probably don't care about navigation anyway, I would expect BackHandler to just silently no-op in this case.

Comments

an...@google.com <an...@google.com> May 26, 2021 12:26PM

Assigned to il...@google.com.

il...@google.com <il...@google.com> #2Jun 2, 2021 12:06AM

Reassigned to an...@google.com.

This is similar to this bug report as well: https://issuetracker.google.com/issues/172590946

an...@google.com <an...@google.com> #3Jun 2, 2021 03:47PM

Reassigned to il...@google.com.

Hi Yinglei, re-assigning back to you as you're currently working on exactly this for Snackbars.

ap...@google.com <ap...@google.com> #4Jun 15, 2021 03:49PM

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

commit 506fcdecc2dc257b58c574006d70ea9ce6f0bfda
Author: Yinglei Wang <yingleiw@google.com>
Date: Fri Feb 26 15:58:00 2021

add semantics liveRegion and apply it to snackbar

Snackbar should be marked as live region for accessibility. When talkback
is on, the snackbar is announced when it appears. Also added dismiss
action for the snackbar.

Note that since we are not merging up the tree for subtree change
events, we don't need to do extra work for live region. From android
documentation and discussion with Phil, the throttling delay is fine for
accessibility events from live region.

Relnote: "LiveRegion accessibility API is added.
If node is marked as a live region, the accessibility services
will automatically notify the user about its changes"

Fix:

b/153644625

b/172590946

b/182834687

Test: tested manully with talkback on. Unit tests added.

Change-Id: Idcf6f425b12b005e59ad77fe7430e466132ea87c

M compose/material/material/src/androidAndroidTest/kotlin/androidx/compose/material/SnackbarHostTest.kt
M compose/material/material/src/commonMain/kotlin/androidx/compose/material/SnackbarHost.kt
M compose/ui/ui/api/1.0.0-beta04.txt
M compose/ui/ui/api/current.txt
M compose/ui/ui/api/public_plus_experimental_1.0.0-beta04.txt
M compose/ui/ui/api/public_plus_experimental_current.txt
M compose/ui/ui/api/restricted_1.0.0-beta04.txt
M compose/ui/ui/api/restricted_current.txt
M compose/ui/ui/src/androidAndroidTest/kotlin/androidx/compose/ui/AndroidComposeViewAccessibilityDelegateCompatTest.kt
M compose/ui/ui/src/androidMain/kotlin/androidx/compose/ui/platform/AndroidComposeViewAccessibilityDelegateCompat.android.kt
M compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/semantics/SemanticsProperties.kt

https://android-review.googlesource.com/1580798

ap...@google.com <ap...@google.com> #5Jun 15, 2021 03:49PM

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

commit 622947a991ba924d4896965f708be022bf1b35ba
Author: Ian Lake <ilake@google.com>
Date: Mon Jun 14 11:34:13 2021

Add a fake OnBackPressedDispatcher to Compose Previews

Rather than having APIs that depend on
LocalOnBackPressedDispatcher crash in @Preview,
provide a fake implementation by default to mirror
the capabilities that are available by default
in a ComponentActivity.

Relnote: "Compose `@Preview` now provides a
`LocalOnBackPressedDispatcherOwner` that allows you
to preview Composables that use APIs like `BackHandler`
that depend on that owner existing."
Test: new ComposeViewAdapterTest test passes
BUG: 185693006

Change-Id: Ia1c05ea3cadf2fb55cef9c4b8bae0898cfb35ba9

M compose/ui/ui-tooling/src/androidAndroidTest/kotlin/androidx/compose/ui/tooling/SimpleComposablePreview.kt
M compose/ui/ui-tooling/src/androidAndroidTest/kotlin/androidx/compose/ui/tooling/preview/ComposeViewAdapterTest.kt
M compose/ui/ui-tooling/src/androidMain/kotlin/androidx/compose/ui/tooling/preview/ComposeViewAdapter.kt

https://android-review.googlesource.com/1736795

il...@google.com <il...@google.com> #6Jun 15, 2021 04:04PM

Marked as fixed.

We've added default a LocalOnBackPressedDispatcherOwner and LocalActivityResultRegistryOwner to @Preview, so APIs that depend on these existing won't crash out of the box.

za...@gmail.com <za...@gmail.com> #7Jun 15, 2021 04:06PM

Thanks!