Android accessibility

Accessibility = Lint nagging…??

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

AppFoundry appfoundry.be

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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 by voice

Brailleback

Switch Access

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

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

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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"

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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 Accessibility Documentation 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 fi[email protected] @fmaelbrancke