Fix viewInset.bottom and viewPadding.bottom…

[LasseRosenow]

… for pre android api 30 devices, to enable edge-to-edge navigation on android 10.

Description

Currently the flutter engine sets the bottom inset for the navigation bar into viewInset.bottom and viewpadding.bottom is always 0 on pre api 30 devices.

If you are using edge-to-edge on api 30 everything works perfectly fine, but on api 29, which is supporting edge-to-edge, we get some issues:

The padding.bottom value is calculated like this: max(0, (viewPadding.bottom - viewInset.bottom))
But if viewPadding.bottom is 0 and viewInset.bottom contains the system navigation bar height, the resulting padding.bottom will be 0.

So for example the BottomNavigationBar widget will not apply bottom padding to have its content on over and not behind the system navigation bar.

Related Issues

• [Android 10] Unable to set transparent navigation bar ([Android 10] Unable to set transparent navigation bar flutter#40974)
• Android 10 incorrect insets when navigation bar is translucent (Android 10 incorrect insets when navigation bar is translucent flutter#63761)
• [Android Q] Transparent navigation bar with extended scaffold ([Android Q] Transparent navigation bar with extended scaffold flutter#34678 )
• Gallery should implement full screen / edge-to-edge for Android Q+ devices (Gallery should implement full screen / edge-to-edge for Android Q+ devices gallery#643)
• Flutter doesn't have a way to handle bottom view insets/notches on Android devices (Flutter doesn't have a way to handle bottom view insets/notches on Android devices flutter#35404)

Tests

I added the following tests:

Replace this with a list of the tests that you added as part of this PR. A
change in behaviour with no test covering it will likely get reverted
accidentally sooner or later. PRs must include tests for all
changed/updated/fixed behaviors. See testing the engine for instructions on
writing and running engine tests.

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Reviewer Checklist

• I have submitted any presubmit flakes in this PR using the engine presubmit flakes form before re-triggering the failure.

Breaking Change

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[LasseRosenow]

The pr is ready for review.

@GaryQian can you review this?

[GaryQian]

This does indeed look like it brings the behavior in line with what is described in https://api.flutter.dev/flutter/widgets/MediaQueryData-class.html. Thanks for the catch.

[GaryQian]

The change will also need to be replicated in the equivalent code in shell/platform/android/io/flutter/view/FlutterView.java

[GaryQian]

This PR also needs tests. The best place to put it would probably be in shell/platform/android/test/io/flutter/embedding/android/FlutterViewTest.java, where systemInsetGetInsetsFullscreenLegacy is likely a good example test to base a new one off of.

[GaryQian]

See comments above :)

[LasseRosenow]

Okay thanks for the review. :)

I will look into it this afternoon

[LasseRosenow]

@GaryQian

I updated all the files based on your feedback.

Regarding the tests, I think that the tests that the available tests should cover my pr, so I only updated them to expect the correct bottomPadding values.

Unfortunately I am struggling, getting the engine compiled and running the tests on my windows pc, so I could not check if my changes to the test file are correct. Would you like to do that? :) If you don't have enough time, I would try to things working on my side, but I don't know how long this will take

[GaryQian]

I may be able to find some time to look at the tests later this week. In the meantime, it should be possible to look at the pre-submit check logs for details on why tests failed. The relevant tests will generally finish running/fail about 10 min after pushing.

You should make sure the tests are changed only for the tests specified for API 29 or below.

[LasseRosenow]

Thats very nice of you. :)
It took me a bit but I figured out how to find the test outputs on github :)
It seems the ones that are failing are tests that are not specified for any api version. I will try to duplicate those tests and create one for api29 and one for api30

[LasseRosenow]

The android tests seem to be working now.

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[chinmaygarde]

This needs to be rebased on ToT as the failing presubmit has been fixed on master. Also @GaryQian, can you take another look and LGTM please. Thanks.

[LasseRosenow]

Okay I rebased it :)

[GaryQian]

LGTM! Thanks for getting the tests done, and I apologize for not getting to it last week. In any case, thank you for the contribution!

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[flutter-dashboard]

This pull request was opened against a branch other than main. Since Flutter pull requests should not normally be opened against branches other than main, I have changed the base to main. If this was intended, you may modify the base back to master. See the Release Process for information about how other branches get updated.

Reviewers: Use caution before merging pull requests to branches other than main, unless this is an intentional hotfix/cherrypick.