Android accessibility

Accessibility /ˈapps for everybody/ Android apps that are usable by everyone. Make no assumptions about the user.

AppFoundry appfoundry.be

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Why?

Assumptions Sight See the screen Mobility Touch the screen Audio Hear Speech Interact

Accessibility? 2 % visual impairment 8 % men color blind 0,1 % blind 8 out of 10 with visual impairment or blindness are older than 65

Accessibility? up to 20 % motor impairment Permanent Parkinson’s Tremor … Situational Injury … Hands busy

Accessibility services Talkback Screen reader Brailleback Braille display Switch Access Control by switch Voice Access Interact

Brailleback

Switch Access

Voice access Voice Assistant High-level voice commands Accessibility Low-level commands Device control Scrolling, clicking, text editing

Android - iOS

Improve user experience for accessibility

Color blindness Normal vision Deuteranopia Protanopia Tritanopia

Contrast

Color correction Accessibility options Color simulation Developer options

Color contrast WCAG : background - foreground : 4.5 contrast ratio

Android Accessibility features Large Text Magnification Gestures High Contrast Text Color inversion Color correction Caption support App developer Text size = sp Layouts = responsive

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Content description

Content description

Meaningful image

Meaningful image

Decorative image

Decorative image

Content description

Content description

States public void setIconAccessibilityText(boolean isFavorite, String teamName) {
 favoriteTeamMenuItem.setTitle(
 isFavorite ?
 ”defavoritise {teamName}” :
 ”mark {teamName} as favorite”;
 }

AccessibilityLiveRegion

AccessibilityLiveRegion

AnnounceForAccessibility private void makeViewVisible() {
 view.setVisibility(View.VISIBLE);
 view.announceForAccessibility(getString(R.string.acc));
 }

AnnounceForAccessibility private void makeViewVisible() {
 view.setVisibility(View.VISIBLE);
 view.announceForAccessibility(getString(R.string.acc));
 }

AnnounceForAccessibility private void setFavoriteListener(final Team team, final boolean isFavorite) {
 view.setOnClickListener(new View.OnClickListener() {
 
 @Override
 public void onClick(View v) {
 teamListener.onTeamClicked(team);
 String announcement = isFavorite
 ? "Removed " + team.displayTitle() + " from favourites"
 : "Added " + team.displayTitle() + " to favourites";
 view.announceForAccessibility(announcement);
 }
 
 });
 }

AnnounceForAccessibility private void setFavoriteListener(final Team team, final boolean isFavorite) {
 view.setOnClickListener(new View.OnClickListener() {
 
 @Override
 public void onClick(View v) {
 teamListener.onTeamClicked(team);
 String announcement = isFavorite
 ? "Removed " + team.displayTitle() + " from favourites"
 : "Added " + team.displayTitle() + " to favourites";
 view.announceForAccessibility(announcement);
 }
 
 });
 }

Control focus order 
 
 
 
 


Control focus order 
 
 
 
 


Filter / change if necessary

Ads ☹ No Ads Accessibility services detected

Talkback detection public boolean isAccessibilityEnabled() { 
 final AccessibilityManager am = (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE); 
 boolean isAccessibilityEnabled = am.isEnabled();
 boolean isExploreByTouchEnabled = am.isTouchExplorationEnabled(); 
 return isAccessibilityEnabled && isExploreByTouchEnabled;
 }

Talkback detection public boolean isAccessibilityEnabled() {
 final AccessibilityManager am = (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE); 
 boolean isAccessibilityEnabled = am.isEnabled();
 boolean isExploreByTouchEnabled = am.isTouchExplorationEnabled(); 
 boolean isSpokenFeedbackEnabled = isSpokenFeedbackEnabled(am);
 return isAccessibilityEnabled && isExploreByTouchEnabled && isSpokenFeedbackEnabled;
 } 
 
 /**
 * Check whether 'spoken feedback' services are enabled.
 */
 private boolean isSpokenFeedbackEnabled(final AccessibilityManager am) {
 List enabledSpokenFeedbackServices = am.getEnabledAccessibilityServiceList(AccessibilityServiceInfo.FEEDBACK_SPOKEN); 
 return !enabledSpokenFeedbackServices.isEmpty();
 }

Content description good / meaningful texts

Meaningful description private void setAccessibilityText(final TeamInfo teamInfo) {
 String accessibilityText;
 if (teamInfo.coaches().isEmpty()) {
 accessibilityText = getString(R.string.no_trainer_acc, teamInfo.teamName());
 } else {
 List trainerNames = getTrainerNames(teamInfo.coaches());
 
 Joiner joiner = Joiner.on(andStr).skipNulls();
 String concatTrainers = joiner.join(trainerNames);
 accessibilityText = getQuantityString(R.plurals.trainer_acc, teamInfo.coaches().size(), teamInfo.teamName(), concatTrainers);
 }
 
 getItemView().setContentDescription(accessibilityText);
 }

Help from your backend

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Custom views

Custom actions

MatchView public interface MatchListener {
 
 void onMatchClicked(Match match);
 
 void onMatchComment(Match match);
 
 void onMatchShare(Match match);
 
 void onMatchLiked(Match match);
 }

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Don’t descend into view android:importantForAccessibility="noHideDescendants"

DIY public void showMatch(final Match match, final MatchListener listener) {
 …
 
 setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View view) {
 if (isAccessibilityEnabled) {
 showCustomActions(match);
 } else {
 listener.onMatchClicked(match);
 }
 }
 });

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Accessibility delegate public static class MatchAccessibilityDelegate extends AccessibilityDelegateCompat {
 
 private final Match match;
 private final MatchListener listener;
 
 public MatchAccessibilityDelegate(final Match match, final MatchListener listener) {
 this.match = match;
 this.listener = listener;
 }
 
 @Override
 public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) {
 super.onInitializeAccessibilityNodeInfo(host, info);
 info.addAction(new AccessibilityNodeInfoCompat.AccessibilityActionCompat(R.id.comment, "Comment"));
 info.addAction(new AccessibilityNodeInfoCompat.AccessibilityActionCompat(R.id.share, "Share"));
 …
 }
 
 @Override
 public boolean performAccessibilityAction(View host, int action, Bundle args) {
 switch (action) {
 case R.id.comment:
 listener.onMatchComment(match);
 return true;
 case R.id.share:
 listener.onMatchShare(match);
 return true;
 …
 return true;


Accessibility delegate public static class MatchAccessibilityDelegate extends AccessibilityDelegateCompat {
 
 private final Match match;
 private final MatchListener listener;
 
 public MatchAccessibilityDelegate(final Match match, final MatchListener listener) {
 this.match = match;
 this.listener = listener;
 }
 
 @Override
 public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) {
 super.onInitializeAccessibilityNodeInfo(host, info);
 info.addAction(new AccessibilityNodeInfoCompat.AccessibilityActionCompat(R.id.comment, "Comment"));
 info.addAction(new AccessibilityNodeInfoCompat.AccessibilityActionCompat(R.id.share, "Share"));
 …
 }
 
 @Override
 public boolean performAccessibilityAction(View host, int action, Bundle args) {
 switch (action) {
 case R.id.comment:
 listener.onMatchComment(match);
 return true;
 case R.id.share:
 listener.onMatchShare(match);
 return true;
 …


Accessibility delegate public void showMatch(final Match match, final MatchListener listener) {
 …
 
 ViewCompat.setAccessibilityDelegate(this, new MatchAccessibilityDelegate(match, listener));
 
 …

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Testing

Manual testing

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Talkback basics Touch to explore Advance through elements (swipe left - right) Double tap selection Gestures for Back, Home, Context menus, …

Accessibility scanner

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Code scanning (Lint)

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Lint rules lintOptions { abortOnError true }

Instrumentation tests

Espresso - Accessibility @Test
 public void testPlayStopButtonContentDescription() {
 final ViewInteraction playButtonInteraction = onView(withId(R.id.play_button));
 playButtonInteraction.check(matches(withContentDescription("Play")));
 
 playButtonInteraction.perform(click());
 playButtonInteraction.check(matches(withContentDescription("Stop")));
 }

Espresso - Accessibility androidTestCompile 'com.android.support.test.espresso:espresso-contrib:2.2.2' @Before
 public void setUp() {
 AccessibilityChecks.enable();
 }

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Accessibility checks com..…AccessibilityViewCheckException: There were 2 accessibility errors: AppCompatImageButton{id=2131427416, res-name=imageButton1, visibility=VISIBLE, width=144, height=132, has- focus=true, has-focusable=true, has-window-focus=false, is-clickable=true, is-enabled=true, is- focused=true, is-focusable=true, is-layout-requested=false, is-selected=false, root-is-layout- requested=false, has-input-connection=false, x=48.0, y=48.0}: View falls below the minimum recommended size for touch targets. Minimum touch target size is 48x48dp. Actual size is 48.0x44.0dp (screen density is 3.0)., AppCompatImageButton{id=2131427416, res-name=imageButton1, visibility=VISIBLE, width=144, height=132, has- focus=true, has-focusable=true, has-window-focus=false, is-clickable=true, is-enabled=true, is- focused=true, is-focusable=true, is-layout-requested=false, is-selected=false, root-is-layout- requested=false, has-input-connection=false, x=48.0, y=48.0}: View is missing speakable text needed for a screen reader at … at android.support.test.espresso.contrib.AccessibilityChecks$2.check(AccessibilityChecks.java:58) at android.support.test.espresso.action.ViewActions$1.perform(ViewActions.java:131) … at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Android Testing Support Library https://developer.android.com/guide/topics/ui/accessibility

Sample github.com/filipmaelbrancke/AndroidAccessibility Accessibility sample Sample used in this presentation: Custom Actions Espresso Test

Resources Accessibility Testing Checklist https://developer.android.com/training/accessibility/testing.html Google’s Accessibility Test Framework github.com/google/Accessibility-Test-Framework-for-Android Espresso Accessibility Checking google.github.io/android-testing-support-library/docs/accesibility-checking/ Talkback Gestures support.google.com/accessibility/android/answer/6151827?hl=en

+ accessibility + accessibility

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Questions? Filip Maelbrancke Consultant @ AppFoundry filip.maelbrancke@appfoundry.be @fmaelbrancke