Source code
Revision control
Copy as Markdown
Other Tools
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
package org.mozilla.fenix.utils
import android.view.View
import androidx.annotation.VisibleForTesting
import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.AppCompatImageButton
import androidx.appcompat.widget.Toolbar
import androidx.core.view.children
import org.mozilla.fenix.HomeActivity
import org.mozilla.fenix.R
/**
* General utilities to to improve a11y support, such as managing screen reader focus.
*/
object AccessibilityUtils {
private val debouncer = AnnouncementDebouncer()
/**
* This function attempts to move focus to the back button on the navigation bar as a generic
* default location to send focus.
*
* Only use this function when focus should be specifically controlled due to TalkBack focus not
* consistently setting or other inconsistent behavior.
*
* Caution, focus should only be manually controlled in certain situations. Be sure this is the
* ideal solution.
*
* @param activity The activity that focus should move to.
*/
fun moveFocusToBackNavButton(activity: AppCompatActivity) {
val toolbar = (activity as HomeActivity).findViewById<Toolbar>(R.id.navigationToolbar)
var backNavigationView: AppCompatImageButton? = null
for (child in toolbar.children) {
if (child is AppCompatImageButton) {
backNavigationView = child
}
}
// Ensures the back button is focusable
backNavigationView?.isFocusableInTouchMode = true
// Clear current focus
backNavigationView?.clearFocus()
backNavigationView?.requestFocus()
// Removes depressed UI state from back button
backNavigationView?.clearFocus()
}
/**
* Sends an accessibility event. The announcement is only triggered after a minimum time interval.
*/
fun View.announcePrivateModeForAccessibility() = debouncer.debounce {
// Using the deprecated method instead of recommended setStateDescription()
// due to limited support when called on binding.root
@Suppress("Deprecation")
announceForAccessibility(
context.getString(R.string.private_browsing_a11y_session_announcement),
)
}
}
/**
* Debounces accessibility announcements so they fire at most once per [debounce] delay window.
*
* @param currentTimeMillis provider for the current time in milliseconds, injectable for testing.
*/
@VisibleForTesting
internal class AnnouncementDebouncer(
private val currentTimeMillis: () -> Long = { System.currentTimeMillis() },
) {
private var lastAnnouncementTime = 0L
/**
* Executes the given [action] only if the time since the last invocation is at least [delay].
*
* @param delay Minimum interval in milliseconds between allowed executions.
* @param action The action to execute.
*/
fun debounce(delay: Long = 2000, action: () -> Unit) {
val currentTime = currentTimeMillis()
if (currentTime - lastAnnouncementTime >= delay) {
lastAnnouncementTime = currentTime
action()
}
}
}