Jetpack Compose: Bottom button moves up with keyboard, want it scrollable instead of resized

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Summary

The issue at hand is related to layout resizing and keyboard overlap in a Jetpack Compose application. When the keyboard opens, the bottom button moves up, and the layout resizes, which is not the desired behavior. The goal is to keep the button at the bottom, allow it to be hidden behind the keyboard, and make the screen scrollable.

Root Cause

The root cause of this issue is the use of imePadding and consumeWindowInsets modifiers in the Surface composable. These modifiers cause the layout to resize when the keyboard opens. Additionally, the ConstraintLayout is set to fill the maximum size of the parent, which also contributes to the resizing issue.

Why This Happens in Real Systems

This issue occurs in real systems due to the following reasons:

  • Keyboard overlap: When the keyboard opens, it overlaps with the layout, causing the system to resize the layout to accommodate the keyboard.
  • Layout constraints: The use of fillMaxSize and ConstraintLayout can lead to layout resizing when the keyboard opens.
  • IME padding: The imePadding modifier is used to add padding to the layout when the keyboard is open, which can cause the layout to resize.

Real-World Impact

The real-world impact of this issue is:

  • Poor user experience: The layout resizing and button movement can cause confusion and frustration for users.
  • Layout inconsistencies: The resizing of the layout can lead to inconsistencies in the layout, making it difficult to design and maintain.
  • Difficulty in scrolling: The lack of scrollability can make it difficult for users to access the bottom button when the keyboard is open.

Example or Code

Scaffold(
    modifier = Modifier
        .fillMaxSize()
        .background(Purple)
) {
    Box(
        modifier = Modifier
            .fillMaxSize()
            .verticalScroll(rememberScrollState())
    ) {
        ConstraintLayout(
            modifier = Modifier
                .fillMaxSize()
                .background(Purple)
        ) {
            val (phoneField, continueButton) = createRefs()
            Box(
                modifier = Modifier
                    .constrainAs(phoneField) {
                        linkTo(parent.top, parent.bottom)
                        linkTo(parent.start, parent.end)
                        width = Dimension.fillToConstraints
                    }
                    .padding(horizontal = 16.dp)
                    .height(100.dp)
            ) {
                BasicTextField(
                    value = phoneNumber,
                    onValueChange = { newValue ->
                        if (newValue.all { it.isDigit() } && newValue.length <= 10) {
                            phoneNumber = newValue
                        }
                    },
                    modifier = Modifier.fillMaxWidth(),
                    singleLine = true,
                    keyboardOptions = KeyboardOptions(
                        keyboardType = KeyboardType.Number
                    )
                )
            }
            Box(
                modifier = Modifier
                    .constrainAs(continueButton) {
                        bottom.linkTo(parent.bottom, 16.dp)
                        linkTo(parent.start, parent.end)
                        width = Dimension.fillToConstraints
                    }
                    .height(42.dp),
                contentAlignment = Alignment.Center
            ) {
                Text("Continue")
            }
        }
    }
}

How Senior Engineers Fix It

Senior engineers fix this issue by:

  • Removing imePadding and consumeWindowInsets: These modifiers are removed to prevent the layout from resizing when the keyboard opens.
  • Using a scrollable container: A Box with a verticalScroll modifier is used to make the screen scrollable.
  • Setting the layout constraints: The ConstraintLayout is set to fill the maximum size of the parent, and the bottom button is constrained to the bottom of the parent.

Why Juniors Miss It

Juniors may miss this issue due to:

  • Lack of understanding of layout constraints: Juniors may not fully understand how layout constraints work in Jetpack Compose, leading to incorrect usage of modifiers and constraints.
  • Insufficient testing: Juniors may not test their application thoroughly, missing the issue when the keyboard opens.
  • Limited experience with keyboard overlap: Juniors may not have experience with handling keyboard overlap in Jetpack Compose, leading to incorrect solutions.

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