Details

A successor of #16356

The first step of react-native-keyboard-controller migration plan

How it works 🤔

This PR is iOS only for now. Other platforms are not affected. Also, in this explanation, we are talking about iOS only since on Android, iOS web and Android Web keyboard handling works differently.

When we long press on a message, we want to be able to see it. It's easy when we have the keyboard closed. But gets tricky when the keyboard is open.

But first of all let's focus on the case when the keyboard is closed. User long press on the message, we render the bottom sheet (action sheet) with some options. If the message is higher than the height of bottom sheet - the message is visible. When the message is the last one (first from the bottom), it can be fully or partially covered by the bottom sheet.

Also everything is tricky when we have keyboard open 😓

To achieve this goal we had to:

• use our own scroll component on iOS for FlatList of ReportListView (it uses reanimated to move the view by the offset)
• use KeyboardAvoiding so we're in sync with keyboard-avoiding style updates
• implement animated style handling using a state machine
• create ActionSheetAwareScrollViewContext to pass the transition function, so we can transition from one state to another by action triggered from different parts of the application

Below you can find more use cases that involves keyboard and other UI elements interactions:

Technical details ⚒️

So in order to calculate the offset for the message, we:

1. Measure the message item in the window using ref.current.measureInWindow, so we can have height and y coordinate of the image
2. Measure the height of the bottom sheet using onLayout callback
3. Get the window height from Dimensions
4. Get safeArea.top since y coordinate doesn't get into account safe area
5. Calculate offset as elementOffset = (y + safeArea.top + itemHeight) - (windowHeight - popoverHeight)
   In order to animate item when they keyboard was open, we need to also know its height which is provided by useAnimatedKeyboard hook from react-native-reanimated, but we should always subtract safeArea.bottom from it since it's not part of the calculation for the offset, but only keyboardHeight.

Overall, the keyboard is the tricky part. On iOS, the keyboard doesn't resize the viewport. So for the content to not be covered by the keyboard, KeyboardAvoidingView is used. In React Native, KeyboardAvoidingView is implemented as a view that changes its height or resizes the children's view by the keyboard height. It's done using RN's Layout Animations. This results in the animation for the keyboard being applied using the native event emitter callback which uses the bridge. So open/close events of the keyboard will always be delayed that resulting in the delayed keyboard avoiding animation and, which is more important, scheduling layout animations.

In order to be consistent 100% of the time with animation and timings, we had to:

• use KeyboardAvoidingView from react-native-keyboard-controller for iOS. It reacts on keyboard height/state change on UI thread in the same frame, so we can schedule an update for styles in the next frame
• use just useDerivedValue for all the logic, since introducing useAnimatedReaction or having multiple shared values will delay updates for 1 frame, but we want to be 100% in sync with keyboard updates
• use paddingTop: translateY (because ScrollView is inverted).

Another important aspect of the implementation is the usage of the state machine for the animation. State machine allows us to specify the chain of events and how to handle them, and more importantly what actions to ignore, for example:

1. Initial state is idle. it can react to KEYBOARD_OPEN action
2. we open emoji picker. it sends EMOJI_PICKER_OPEN action
3. there is no handling for this action in idle state so we do nothing
4. we close emoji picker and it sends EMOJI_PICKER_CLOSE action which again does nothing
5. we open keyboard. it sends KEYBOARD_OPEN action. idle can react to this action by transitioning into keyboardOpen state
6. our state is keyboardOpen. it can react to KEYBOARD_CLOSE, EMOJI_PICKER_OPEN actions
7. we open emoji picker again. it sends EMOJI_PICKER_OPEN action which transitions our state into emojiPickerOpen state. now we react only to EMOJI_PICKER_CLOSE action
8. before rendering the emoji picker, the app hides the keyboard. it sends KEYBOARD_CLOSE action. but we ignore it since our emojiPickerOpen state can only handle EMOJI_PICKER_CLOSE action. so we write the logic for handling 9. hiding the keyboard but maintaining the offset based on the keyboard state shared value
9. we close the picker and send EMOJI_PICKER_CLOSE action which transitions us back into keyboardOpen state.

Fixed Issues

$ #10632
PROPOSAL: N/A

Tests

These steps were performed on all the platforms. The new behavior is iOS only for now.

1. Open chat
2. Long press on the first message - message should be pushed up to be displayed above the bottom sheet
3. Long press on the top message - if the message is not covered by the bottom sheet, it should stay in place
4. Long press on any attachment (document, message) should result in the same behavior

Before each next we make sure the keyboard is open:

1. Long press on the message should either animate the message above the bottom sheet or keep it in place
2. Messages should not "jump" because of keyboard hide/open when showing bottom sheet, emoji picker
3. Press on emoji picker in the composer, messages should stay in place even though the keyboard was closer - emoji picker is rendered instead of keyboard
4. Long press on the mesage, click on add reactions - close emoji reactions

• Verify that no errors appear in the JS console

Offline tests

Should not affect the offline state.

QA Steps

Same as Tests

• Verify that no errors appear in the JS console

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
  • MacOS: Desktop
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
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• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
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• I verified any variables that can be defined as constants (ie. in CONST.js or at the top of the file that uses the constant) are defined as such
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  • The file has a description of what it does and/or why is needed at the top of the file if the code is not self explanatory
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  • A similar style doesn't already exist
  • The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(theme.componentBG))
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
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• If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
  • I verified that all the inputs inside a form are aligned with each other.
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• If a new page is added, I verified it's using the ScrollView component to make it scrollable when more elements are added to the page.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.

Screenshots/Videos