Icon buttons

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Icon buttons display actions that users can take. Icon buttons must use an icon with a clear meaning, and typically represent common or frequently used actions.

There are two types of icon buttons:

• Default: These buttons can open other elements, such as a menu or search.
• Toggle: These buttons can represent binary actions that can be toggled on or off, such as "favorite" or "bookmark".

API surface

Use the IconButton composable to implement standard icon buttons. To create different visual styles like filled, filled tonal, or outlined, use FilledIconButton, FilledTonalIconButton, and OutlinedIconButton, respectively.

The key parameters for IconButton include:

• onClick: A lambda function that executes when the user taps the icon button.
• enabled: A boolean that controls the enabled state of the button. When false, the button does not respond to user input.
• content: The composable content inside the button, typically an Icon.

Basic example: Toggle icon button

This example shows you how to implement a toggle icon button. A toggle icon button changes its appearance based on whether it's selected or unselected.

@Preview
@Composable
fun ToggleIconButtonExample() {
    // isToggled initial value should be read from a view model or persistent storage.
    var isToggled by rememberSaveable { mutableStateOf(false) }

    IconButton(
        onClick = { isToggled = !isToggled }
    ) {
        Icon(
            painter = if (isToggled) painterResource(R.drawable.favorite_filled) else painterResource(R.drawable.favorite),
            contentDescription = if (isToggled) "Selected icon button" else "Unselected icon button."
        )
    }
}
IconButton.kt

Key points about the code

• The ToggleIconButtonExample composable defines a toggleable IconButton.
  • mutableStateOf(false) creates a MutableState object that holds a boolean value, initially false. This makes isToggled a state holder, meaning Compose recomposes the UI whenever its value changes.
  • rememberSaveable ensures the isToggled state persists across configuration changes, like screen rotation.
• The onClick lambda of the IconButton defines the button's behavior when clicked, toggling the state between true and false.
• The Icon composable's painter parameter conditionally loads a different painterResource based on the isToggled state. This changes the visual appearance of the icon.
  • If isToggled is true, it loads the filled heart drawable.
  • If isToggled is false, it loads the outlined heart drawable.
• The contentDescription of the Icon also updates based on the isToggled state to provide appropriate accessibility information.

Result

The following image shows the toggle icon button from the preceding snippet in its unselected state:

Advanced example: Repeated actions on press

This section demonstrates how to create icon buttons that continuously trigger an action while the user presses and holds them, rather than just triggering once per click.

@Composable
fun MomentaryIconButton(
    unselectedImage: Int,
    selectedImage: Int,
    contentDescription: String,
    modifier: Modifier = Modifier,
    stepDelay: Long = 100L, // Minimum value is 1L milliseconds.
    onClick: () -> Unit
) {
    val interactionSource = remember { MutableInteractionSource() }
    val isPressed by interactionSource.collectIsPressedAsState()
    val pressedListener by rememberUpdatedState(onClick)

    LaunchedEffect(isPressed) {
        while (isPressed) {
            delay(stepDelay.coerceIn(1L, Long.MAX_VALUE))
            pressedListener()
        }
    }

    IconButton(
        modifier = modifier,
        onClick = onClick,
        interactionSource = interactionSource
    ) {
        Icon(
            painter = if (isPressed) painterResource(id = selectedImage) else painterResource(id = unselectedImage),
            contentDescription = contentDescription,
        )
    }
}
IconButton.kt

Key points about the code

• MomentaryIconButton takes an unselectedImage: Int, the drawable resource ID for the icon when the button is not pressed, and selectedImage: Int, the drawable resource ID for the icon when the button is pressed.
• It uses an interactionSource to specifically track "press" interactions from the user.
• isPressed is true when the button is actively being pressed and false otherwise. When isPressed is true, the LaunchedEffect enters a loop.
  • Inside this loop, it uses a delay (with stepDelay) to create pauses between triggering actions. coerceIn ensures the delay is at least 1ms to prevent infinite loops.
  • The pressedListener is invoked after each delay within the loop. This makes the action repeat.
• The pressedListener uses rememberUpdatedState to ensure that the onClick lambda (the action to perform) is always the most up-to-date from the latest composition.
• The Icon changes its displayed image based on whether the button is currently pressed or not.
  • If isPressed is true, the selectedImage is shown.
  • Otherwise, the unselectedImage is shown.

Next, use this MomentaryIconButton in an example. The following snippet demonstrates two icon buttons controlling a counter:

@Preview()
@Composable
fun MomentaryIconButtonExample() {
    var pressedCount by remember { mutableIntStateOf(0) }

    Row(
        modifier = Modifier.fillMaxWidth(),
        verticalAlignment = Alignment.CenterVertically
    ) {
        MomentaryIconButton(
            unselectedImage = R.drawable.fast_rewind,
            selectedImage = R.drawable.fast_rewind_filled,
            stepDelay = 100L,
            onClick = { pressedCount -= 1 },
            contentDescription = "Decrease count button"
        )
        Spacer(modifier = Modifier)
        Text("advanced by $pressedCount frames")
        Spacer(modifier = Modifier)
        MomentaryIconButton(
            unselectedImage = R.drawable.fast_forward,
            selectedImage = R.drawable.fast_forward_filled,
            contentDescription = "Increase count button",
            stepDelay = 100L,
            onClick = { pressedCount += 1 }
        )
    }
}
IconButton.kt

Key points about the code

• The MomentaryIconButtonExample composable displays a Row containing two MomentaryIconButton instances and a Text composable to build a UI for incrementing and decrementing a counter.
• It maintains a pressedCount mutable state variable using remember and mutableIntStateOf, initialized to 0. When pressedCount changes, any composables observing it (like the Text composable) recompose to reflect the new value.
• The first MomentaryIconButton decreases pressedCount when clicked or held.
• The second MomentaryIconButton increases pressedCount when clicked or held.
• Both buttons use a stepDelay of 100 milliseconds, meaning the onClick action repeats every 100ms while a button is held.

Result

The following video shows the UI with the icon buttons and the counter:

Additional resources

• Material 3 - Icon buttons