Android accessibility 9th_april_droidcon
- 1. Google Confidential and Proprietary Designing Accessible Android Applications April 9, 2013
- 2. Google Confidential and Proprietary Agenda ● What is accessibility? ● What features are available? ● How do you make your app accessible? ● Testing and Debugging
- 3. Google Confidential and Proprietary
- 4. Google Confidential and Proprietary What framework provides ● User interactions and system events generate AccessibilityEvents and send them to services ● AccessibilityServices like TalkBack respond to these events and provide feedback to the user
- 5. Google Confidential and Proprietary What framework provides Donut (1.6) through Honeycomb (3.x) ● Spoken feedback through TextToSpeech APIs ● Modify your device's display and sound options ○ Large text ○ Change speed at which text is spoken ○ Disable screen rotation Ice Cream Sandwich (4.0) ● Touch exploration for devices without D-Pad ● Services can inspect view hierarchy
- 6. Google Confidential and Proprietary What framework provides JellyBean (4.1) ● Supports Accessibility focus ○ Services can place this focus on any view ○ Indicated on-screen via yellow rectangle ● Supports Braille I/O devices via BrailleBack service
- 7. Google Confidential and Proprietary What framework provides JellyBean (4.1) ● Many actions available ○ Move input focus ○ Click on views ○ Scroll within views ○ Navigate text by words, etc. ○ Perform global actions
- 8. Google Confidential and Proprietary Features in Jelly Bean Gestures ● Services can respond to user- drawn gestures ○ Perform accessibility actions ○ Invoke global actions (Home, Back, etc.) ● Deterministic access to screen content
- 9. Google Confidential and Proprietary Features in Jelly Bean Magnification ● Available in Android 4.2 ● Multiple zoom modes ○ Triple-tap to toggle ○ Triple-tap and hold for momentary zoom
- 10. Google Confidential and Proprietary Features in Jelly Bean Gestures ● Quick shortcuts available in Global Context Menu ○ Pause feedback ○ Repeat/spell last utterance ○ TalkBack Settings
- 11. Google Confidential and Proprietary (demo)
- 12. Google Confidential and Proprietary What framework provides Android sensors ● SMS, Video chats, Videos with Captions ● Location aware, GPS, maps, places ● proximity ● eyes free - motion / accelerometer / velocity tracker / light sensor ● motion, environmental and position sensors Read the Android Developer Guide for Sensors
- 13. Google Confidential and Proprietary What framework provides Google Play ● Paid apps in many Countries ● DCB Developer Console ● Countries and currencies ● Auto Translate feature ● Statistics Global accessibility ● i18n and l10n Read the Android Developer Guide for Localization
- 14. Google Confidential and Proprietary What framework provides Design recommendations ● Navigation should be easy ● Use recommended touch target sizes ● Alternatives to time-out controls ● Label UI elements meaningfully ○ Minimize Chatter ○ Provide feedback Read the Android Design Guide for Accessibility
- 15. Google Confidential and Proprietary (demo)
- 16. Google Confidential and Proprietary Code changes for Accessibility Labeling content ● Controls without text need android:contentDescription ● Android Lint tool warns when images are missing descriptions ● Purely decorative Views should set android: contentDescription="@null" ● Use setContentDescription() to update a View's description ○ Don't override getContentDescription() ● EditTexts should use android:hint
- 17. Google Confidential and Proprietary <ImageView android:id="@+id/rounded_corner" android:contentDescription="@null" ... /> <ImageView android:id="@+id/search_button" android:focusable=”true” android:contentDescription="@string/search" ... /> <EditText android:id="@+id/search_field" android:hint="@string/search_hint" ... />
- 18. Google Confidential and Proprietary Code changes for Accessibility Supporting D-Pad navigation ● Prior to Android 4.0, app needs to be accessible via D-Pad ○ Includes arrow keys on USB and Bluetooth keyboards ○ This is easy to test in the emulator! ● May need to manually specify that clickable items (e.g. ImageViews) are focusable using android:focusable="true" ● Make important text focusable ● Control order using android:nextFocusDown
- 19. Google Confidential and Proprietary <LinearLayout android:orientation="horizontal" ... > <EditText android:id="@+id/edit" android:focusable=”true” android:nextFocusDown=”@+id/text” ... /> <TextView android:id="@+id/text" android:focusable=”true” android:text="@string/terms_of_service" android:nextFocusUp=”@id/edit” ... /> </LinearLayout>
- 20. Google Confidential and Proprietary Code changes for Accessibility Supporting scaled text ● Android supports large fonts for low-vision use ● Text sizes should be in sp "scaled pixels" instead of dips ● Always test your app for text cropping, wrapping, etc. ○ You should be doing this for i18n anyway! <TextView android:id="@+id/intro_text" android:textSize="14sp" .... />
- 21. Google Confidential and Proprietary (demo)
- 22. Google Confidential and Proprietary Logical grouping and ordering ● View hierarchy order and on-screen positioning determine grouping for accessibility focus and ordering of spoken feedback ● Group non-focusable items (e.g. TextViews) in a focusable container to have them read as a single item ● Set content description on a container to override automatic grouping and ordering of contained items
- 23. Google Confidential and Proprietary Logical grouping and ordering
- 24. Google Confidential and Proprietary FolderIcon android:id="@+id/folder" android:focusable="true" android:contentDescription="@string/folder_google" ...> <ImageView android:id="@+id/preview_background" android:contentDescription="@null" ... /> <BubbleTextView android:id="@+id/folder_icon_name" android:text="@string/google" ... /> </LinearLayout>
- 25. Google Confidential and Proprietary Testing and Debugging for Accessibility For all Android apps ○ Create checklist ○ Check with real simulation ○ Test on all supported Platforms ○ Test on screens and densities Screens: small, normal, large, xlarge Densities: (low (ldpi), medium (mdpi), high (hdpi), extra high (xhdpi))
- 26. Google Confidential and Proprietary Testing and Debugging for Accessibility For all Android apps ● Enable Accessibility features ○ Turn on TalkBack logging in Accessibility > TalkBack > Settings > Developer settings ● Android Lint tool
- 27. Google Confidential and Proprietary Summary Must do: ● Use built-in Android components ○ Label controls ○ Make controls focusable ○ Ensure traversal order is correct ○ Specify text in sp ○ Logically group UI elements ● Fix custom components ○ Implement accessibility interfaces ○ Use Support library ○ TouchExplorationHelper is available on Google Code ● Test and Fix
- 28. Google Confidential and Proprietary Summary Good to have: ● Augment audio-only prompts ○ Visual cues ○ Haptic feedback ● Evaluate sensors ● Add captions to videos ● Follow UI guidelines ● Reach globally Read the Android Developer Guide for Accessibility
- 29. Google Confidential and Proprietary Thanks and Questions? Send feedback to: soniash@google.com