Support singleLine and KeyboardAction on iOS

[paxbun]

Proposed Changes

For iOS singleLine and KeyboardAction support

• Added UIKitTextInputService.runImeActionRequired that checks whether a keyboard action needs to be called and calls it if needed
• Added UIKitTextInputService.onPreviewKeyEvent for hardware keyboard event debouncing
• Made UIKitTextInputService.skikoInput.insertText call UIKitTextInputService.runImeActionRequired when the given character is a new line character
• Prevented UIKitTextInputService.skikoInput.insertText from adding a new line character when singleLine is true or a keyboard action needs to be called
• Passed UIKitTextInputService::onPreviewKeyEvent to ComposeLayer.setContent from ComposeWindow
• Added return key press event debouncing logic when calling an IME action

On some Android devices, the behavior of text fields is different when with hardware keyboards and with software keyboards. As you can see in the video below, on Android, the behavior of ImeAction.Search with singleLine = false is different, where the Search action is called with software keyboards while not called with hardware keyboards. Also, on some virtual Android devices (for me, it was Resizable (Experimental) API 33), when singleLine is true and the current IME action is ImeAction.Default, the Done action is called with software keyboards while not called with hardware keyboards.

The current behavior of text fields in this PR is as follows. When an IME action is called, the new line character is always prevented from being added.

Actions	singleLine = true	singleLine = false
ImeAction.Default	Calls the Done action.	Does nothing
ImeAction.None	Prevents a new line character from being added.	Does nothing
ImeAction.Search	Calls the Search action.	Calls the Search action only when the software keyboard is used, does nothing otherwise
Others	Calls the corresponding action regardless of the value of singleLine.

For iOS hardware keyboard bug fix

• Made UIKitTextInputService.onPreviewKeyEvent consume KEY_ENTER and KEY_BACKSPACE down events to prevent double new line characters or double character removing when using hardware keyboards

Testing

Test: Tested using the Android & iOS template with the following configuration:

• (Ground Truth) Galaxy Tab S8 with Samsung Keyboard
• (Ground Truth) Galaxy Tab S8 with a hardware keyboard (via Bluetooth)
• iPad Pro, 11-inch (3rd generation) (iOS 16.5.1) with the system keyboard
• iPad Pro, 11-inch (3rd generation) (iOS 16.5.1) with Magic Keyboard (via Universal Control, but Bluetooth works the same)

App.kt is modified as the code below.

Issues Fixed

Fixes: JetBrains/compose-multiplatform#2794

Test Code

private val imeActions = arrayOf(
    ImeAction.Default,
    ImeAction.Done,
    ImeAction.Go,
    ImeAction.Next,
    ImeAction.None,
    ImeAction.Previous,
    ImeAction.Search,
    ImeAction.Send,
)

@Composable
fun App() {
    MaterialTheme {
        var currentAction by remember { mutableStateOf(ImeAction.Default) }
        val (singleLine, setSingleLine) = remember { mutableStateOf(false) }
        val (value, setValue) = remember { mutableStateOf("") }
        val keyboardActionsCalled = remember { mutableStateListOf<String>() }
        LaunchedEffect(keyboardActionsCalled.toTypedArray()) {
            delay(0.5.seconds)
            if (keyboardActionsCalled.isNotEmpty()) {
                keyboardActionsCalled.removeLast()
            }
        }
        Column {
            Row(
                modifier = Modifier.horizontalScroll(rememberScrollState()),
                horizontalArrangement = Arrangement.spacedBy(20.dp),
            ) {
                imeActions.forEach { action ->
                    Row {
                        RadioButton(
                            selected = currentAction == action,
                            onClick = { currentAction = action },
                        )
                        Text(action.toString())
                    }
                }
            }
            Row {
                Checkbox(singleLine, setSingleLine)
                Text("Single Line")
            }
            keyboardActionsCalled.forEach {
                Text("$it is called")
            }
            Row {
                TextField(
                    value = value,
                    onValueChange = setValue,
                    keyboardOptions = KeyboardOptions(
                        imeAction = currentAction
                    ),
                    keyboardActions = KeyboardActions(
                        onDone = { keyboardActionsCalled += "Done" },
                        onGo = { keyboardActionsCalled += "Go" },
                        onNext = { keyboardActionsCalled += "Next" },
                        onPrevious = { keyboardActionsCalled += "Previous" },
                        onSearch = { keyboardActionsCalled += "Search" },
                        onSend = { keyboardActionsCalled += "Send" },
                    ),
                    singleLine = singleLine,
                )
                Button({ setValue("") }) {
                    Text("Clear")
                }
            }
        }
    }
}

Test Results (iOS singleLine and KeyboardAction support)

Galaxy.Tab.S8.Software.mp4

Galaxy.Tab.S8.Hardware.mp4

iPad.Pro.Software.mov

iPad.Pro.Hardware.MP4

Test Results (iOS hardware keyboard bug fix)

Tested with hello <return> <return> world <backspace> <backspace>.

Before the fix:

iPad.Pro.Before.MP4

After the fix:

iPad.Pro.After.MP4

[dima-avdeev-jb]

Hello! Big thanks, it looks very usefull

But, first can you please sign the Google Contributor’s License Agreement at https://cla.developers.google.com/.
This is needed since we synchronise most of the code with Google’s AOSP repository. Signing this agreement allows us to synchronise code from your Pull Requests as well.

As a referece, you can look at screenshots in this PR: #521

[dima-avdeev-jb]

And can you please provide a screenshot of the signed agreement?

[paxbun]

Here it is (I re-signed it, just in case):

[dima-avdeev-jb]

Thanks for a screenshot!
I will check this PR

[dima-avdeev-jb]

You got 1 approve! But please wait for my approve too.

[devjorgecastro]

Here it is (I re-signed it, just in case):

Excuse my ignorance, but what does the image mean?

[paxbun]

@devjorgecastro That image shows that I'm registered as a contributor to Google's open-source projects. Contributions here will eventually be merged into the original Google repository, so you have to sign in at https://cla.developers.google.com/ if you want to make a PR.