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CustomStateDescriptions.md

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Custom State Descriptions

Some standard Android composables also contain state which they expose to Accessibility Services. For example, a Checkbox composable has two states announced by TalkBack as "checked" and "not checked". Similarly, the Switch composable has the states "On" and "Off". It is possible to customize these state descriptions to improve the user experience in TalkBack.

To change the state description of a stateful composable, use the Modifier.semantics stateDescription property as follows:

val (isAlarmActive, setIsAlarmActive) = remember { mutableStateOf(false) }
Row(
    modifier = modifier
        .toggleable(
            value = isAlarmActive,
            role = Role.Checkbox,
            onValueChange = setIsAlarmActive
        )
        .semantics {
            // Key technique: Set the Modifier.semantics stateDescription property based on the 
            // toggleable widget's current state.
            stateDescription = if (isAlarmActive) "Activated" else "Deactivated"
        },
    verticalAlignment = Alignment.CenterVertically
) {
    Checkbox(
        checked = isAlarmActive,
        onCheckedChange = null,
        modifier = Modifier.minimumInteractiveComponentSize()
    )
    Text("Home alarm system")
}

This Checkbox will announce its state in TalkBack as "Activated" or "Deactivated" instead of "Checked" and "Not checked".

Notes:

  • Customizing stateDescription may not work successfully on all Android platforms; ViewCompat.setStateDescription() certainly does not. However, if stateDescription does not work, the standard state description text is announced. So attempting to improve the user experience by customizing the state description does no harm.
  • The hard-coded text shown in these examples is only used for simplicity. Always use externalized string resource references in actual code.
    • When strings are externalized, the conditional code determining the localized state description value should be moved outside of the Modifier.semantics block so stringResource() can be called in a Composable context.

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