KeyboardAvoidingView: update bottom height when frame height is changed

[lyqandy]

Summary:

Fix this issue: #29499

• We should change the bottom height if the frame height of KeyboardAvoidingView is changed

In some scenarios, the height of KeyboardAvoidingView would be changed because its container is re-layouted. So onLayout of KeyboardAvoidingView may be triggered more than once.

react-native/packages/react-native/Libraries/Components/Keyboard/KeyboardAvoidingView.js

Lines 114 to 125 in bbc3657

	_onLayout = async (event: ViewLayoutEvent) => {
	const wasFrameNull = this._frame == null;
	this._frame = event.nativeEvent.layout;
	if (!this._initialFrameHeight) {
	// save the initial frame height, before the keyboard is visible
	this._initialFrameHeight = this._frame.height;
	}
	if (wasFrameNull) {
	await this._updateBottomIfNecessary();
	}

But at line 122 above, _updateBottomIfNecessary would be called only for the first trigger of onLayout. That means, if the height of KeyboardAvoidingView is changed, the bottom height can't be updated.

See the videos below:

before

In this video, KeyboardAvoidingView is rendered twice, and the height is changed from 844 to 753, bottomHeight is not updated when the height changed, so there is a white gap below the continue button. Once I re-open the keyboard, _updateBottomIfNecessary is called again, then the white gap disappeared.

before-fix.mp4

after

after-fix.mp4

Changelog:

[GENERAL] [CHANGED] - change _onLayout to update bottom height when frame height is changed

Test Plan:

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[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	8,620,320	+29
android	hermes	armeabi-v7a	7,932,992	+20
android	hermes	x86	9,106,281	+32
android	hermes	x86_64	8,961,112	+42
android	jsc	arm64-v8a	9,186,904	+14
android	jsc	armeabi-v7a	8,377,199	+27
android	jsc	x86	9,244,478	+26
android	jsc	x86_64	9,502,982	+21

Base commit: 54f7b8b
Branch: main

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[NickGerleman]

Reading around this I saw that the same function is called in the event of keyboardWillChangeFrame. Do we not see the event in this case?

edit: Oh the frame here is that of the view, and not of the keyboard.

[NickGerleman]

This change seems good to me, but for someone not very familiar with this logic, could you explain the sequence of events/the math here a bit?

[lyqandy]

This change seems good to me, but for someone not very familiar with this logic, could you explain the sequence of events/the math here a bit?

Hi @NickGerleman , I have updated the Summary, you can take a look :).

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@NickGerleman has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@NickGerleman merged this pull request in 5059ddc.