Android Accessibility at GDG Devfest Brussels 2016

'Accessibility for everyone' session at the GDG Brussels 2016 Devfest.

Transcript

1. Android accessibility
2. Accessibility /ˈapps for everybody/ Android apps that are usable by everyone. Make no assumptions about the user.
3. AppFoundry appfoundry.be
7. Why?
8. Assumptions Sight See the screen Mobility Touch the screen Audio Hear Speech Interact
9. Accessibility? 2 % visual impairment 8 % men color blind 0,1 % blind 8 out of 10 with visual impairment or blindness are older than 65
10. Accessibility? up to 20 % motor impairment Permanent Parkinson’s Tremor … Situational Injury … Hands busy
11. Accessibility services Talkback Screen reader Brailleback Braille display Switch Access Control by switch Voice Access Interact
12. Brailleback
13. Switch Access
14. Voice access Voice Assistant High-level voice commands Accessibility Low-level commands Device control Scrolling, clicking, text editing
15. Android - iOS
16. Improve user experience for accessibility
17. Color blindness Normal vision Deuteranopia Protanopia Tritanopia
18. Contrast
19. Color correction Accessibility options Color simulation Developer options
20. Color contrast WCAG : background - foreground : 4.5 contrast ratio
21. Android Accessibility features Large Text Magnification Gestures High Contrast Text Color inversion Color correction Caption support App developer Text size = sp Layouts = responsive
23. Content description <TextView
 android:id="@+id/day"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="@string/mon"
 android:contentDescription="@string/monday" />
24. Content description <TextView
 android:id="@+id/day"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="@string/mon"
 android:contentDescription="@string/monday" />
25. Meaningful image <ImageView
 android:id="@+id/action_mode_close_button"
 android:contentDescription="Done"
 android:focusable="true"
 android:clickable="true"
 app:srcCompat="?attr/actionModeCloseDrawable"
 style="?attr/actionModeCloseButtonStyle"
 android:layout_width="wrap_content"
 android:layout_height="match_parent"/>
26. Meaningful image <ImageView
 android:id="@+id/action_mode_close_button"
 android:contentDescription="Done"
 android:focusable="true"
 android:clickable="true"
 app:srcCompat="?attr/actionModeCloseDrawable"
 style="?attr/actionModeCloseButtonStyle"
 android:layout_width="wrap_content"
 android:layout_height="match_parent"/>
27. Decorative image <ImageView
 android:contentDescription=“@null"
 app:srcCompat=“@drawable/decoration“
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"/>
28. Decorative image <ImageView
 android:contentDescription=“@null"
 app:srcCompat=“@drawable/decoration“
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"/>
29. Content description <RelativeLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:contentDescription="@string/acc">
30. Content description <RelativeLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:contentDescription="@string/acc">
31. States public void setIconAccessibilityText(boolean isFavorite, String teamName) {
 favoriteTeamMenuItem.setTitle(
 isFavorite ?
 ”defavoritise {teamName}” :
 ”mark {teamName} as favorite”;
 }
32. AccessibilityLiveRegion <TextView
 android:id="@+id/evaluation_result"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:accessibilityLiveRegion="polite"/>
33. AccessibilityLiveRegion <TextView
 android:id="@+id/evaluation_result"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:accessibilityLiveRegion="polite"/>
34. AnnounceForAccessibility private void makeViewVisible() {
 view.setVisibility(View.VISIBLE);
 view.announceForAccessibility(getString(R.string.acc));
 }
35. AnnounceForAccessibility private void makeViewVisible() {
 view.setVisibility(View.VISIBLE);
 view.announceForAccessibility(getString(R.string.acc));
 }
36. 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);
 }
 
 });
 }
37. 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);
 }
 
 });
 }
38. Control focus order <LinearLayout
 android:orientation="horizontal">
 
 <EditText
 android:id="@+id/edit"
 android:nextFocusForward="@+id/text" />
 
 <TextView
 android:id="@+id/text"
 android:focusable="true"
 android:text="Hello, I am a focusable TextView" />
 </LinearLayout>
39. Control focus order <LinearLayout
 android:orientation="horizontal">
 
 <EditText
 android:id="@+id/edit"
 android:nextFocusForward="@+id/text" />
 
 <TextView
 android:id="@+id/text"
 android:focusable="true"
 android:text="Hello, I am a focusable TextView" />
 </LinearLayout>
40. Filter / change if necessary
41. Ads ☹ No Ads Accessibility services detected
42. 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;
 }
43. 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<AccessibilityServiceInfo> enabledSpokenFeedbackServices = am.getEnabledAccessibilityServiceList(AccessibilityServiceInfo.FEEDBACK_SPOKEN); 
 return !enabledSpokenFeedbackServices.isEmpty();
 }
44. Content description good / meaningful texts
45. 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<String> 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);
 }
46. Help from your backend
49. Custom views
50. Custom actions
51. MatchView public interface MatchListener {
 
 void onMatchClicked(Match match);
 
 void onMatchComment(Match match);
 
 void onMatchShare(Match match);
 
 void onMatchLiked(Match match);
 }
53. Don’t descend into view android:importantForAccessibility="noHideDescendants"
54. 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);
 }
 }
 });
57. 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;

58. 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;
 …

59. Accessibility delegate public void showMatch(final Match match, final MatchListener listener) {
 …
 
 ViewCompat.setAccessibilityDelegate(this, new MatchAccessibilityDelegate(match, listener));
 
 …
61. Testing
62. Manual testing
64. Talkback basics Touch to explore Advance through elements (swipe left - right) Double tap selection Gestures for Back, Home, Context menus, …
65. Accessibility scanner
71. Code scanning (Lint)
74. Lint rules <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="ContentDescription" severity="error" /> </lint> lintOptions { abortOnError true }
75. Instrumentation tests
76. 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")));
 }
77. Espresso - Accessibility androidTestCompile 'com.android.support.test.espresso:espresso-contrib:2.2.2' @Before
 public void setUp() {
 AccessibilityChecks.enable();
 }
79. 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)
80. Android Testing Support Library https://developer.android.com/guide/topics/ui/accessibility
81. Sample github.com/filipmaelbrancke/AndroidAccessibility Accessibility sample Sample used in this presentation: Custom Actions Espresso Test
82. 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
83. + accessibility + accessibility
85. Questions? Filip Maelbrancke Consultant @ AppFoundry filip.maelbrancke@appfoundry.be @fmaelbrancke