Improve accessibility of checkbox.

[johnjohndoe]

• Add missing Checkbox role which is only set if onClick is set.
• Add state description to output the checked state via TalkBack.

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Relates #453, #417, #318

[johnjohndoe]

Where do you want strings to be maintained in the project?

[mikepenz]

I wonder if we can depend on the string from the material component, or mimic that one, as I would hope that they handle it properly already

[johnjohndoe]

Yes, I agree. Ultimately it would be patched there to not depend on the handler being set.

[keta1]

https://github.com/androidx/androidx/blob/b55ab743eb05c12eac83aa9c77900bd2c4eb773f/compose/material/material/src/commonMain/kotlin/androidx/compose/material/Checkbox.kt#L141

@Composable
fun Checkbox(
    checked: Boolean,
    onCheckedChange: ((Boolean) -> Unit)?,
    modifier: Modifier = Modifier,
    enabled: Boolean = true,
    interactionSource: MutableInteractionSource? = null,
    colors: CheckboxColors = CheckboxDefaults.colors(),
) {
    TriStateCheckbox(
        state = ToggleableState(checked),
        onClick =
            if (onCheckedChange != null) {
                { onCheckedChange(!checked) }
            } else null,
        interactionSource = interactionSource,
        enabled = enabled,
        colors = colors,
        modifier = modifier,
    )
}

val toggleableModifier =
        if (onClick != null) {
            Modifier.triStateToggleable(
                state = state,
                onClick = onClick,
                enabled = enabled,
                role = Role.Checkbox,
                interactionSource = interactionSource,
                indication = ripple(bounded = false, radius = CheckboxRippleRadius),
            )
        } else {
            Modifier
        }

it may only be necessary to pass an empty lambda to onCheckedChange

[johnjohndoe]

Thanks, I will try that out.

[johnjohndoe]

Yes, once I set onCheckedChange = { _ -> }, then TalkBack will read out the checked state. It does break the layout though:

Also, once I set semantics(mergeDescendants = true) {} on the Row in MarkdownListItem then the checkbox state is not longer output.

[johnjohndoe]

⏸️ I won't be able to work on this within this month.

[johnjohndoe]

I rebased the branch and check the rendering and TalkBack output again. Now it looks fine - to layout issue anymore. Hence, ready for review.