Android accessibility till_kitkat_nov2013_andevcon

Google Confidential and Proprietary

Designing AccessibleAndroid Applications(information provided till Kitkat)

Nov, 2013

Sample Projecthttp://goo.gl/m3LUx

http://goo.gl/m3LUx

http://goo.gl/m3LUx


Agenda

WHAT WHY HOW

is Accessibility? do we care? to implement it?

is provided in Framework?

to test it?


What is Accessibility. Mostly used for people with special needs.

Visual

motion

Hearing

Visual


Why make your apps accessible?

Reach!

Approximate number of people with special needs



Reach!

Approximate number of people with special needs

~1 billion users out of 7 billion



Empowering users!We don’t use all the senses every time..


How?

Feedback in many ways

sight (visual)hear (audio)touch (haptic) tastesmell

No taste and smell feedback in apps yet !


What framework provides

● User interactions and system events generate AccessibilityEvents and send them to services

● AccessibilityServices like TalkBack and BrailleBack respond to these events and provide feedback to the user


What framework provides - Accessibility Services

TalkBack (Froyo and above)Provides spoken, auditory, and haptic feedbackAllows for random access and linear access of content

BrailleBack (Jelly Bean and above)Allows users to access content on virtual braille displaySupports navigation and text input from a braille keyboard



Donut (1.6) through Honeycomb (3.x)● Spoken feedback through TextToSpeech APIs● Power button ends call● 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



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



JellyBean (4.1)

● Many actions available○ Move input focus○ Click on views○ Scroll within views○ Navigate text by words, etc.○ Perform global actions


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


Features in Jelly BeanUpdated in Kitkat

Gestures

● Quick shortcuts available in Global Context Menu


Features in Jelly Bean

Magnification

● Available in Android 4.2● Multiple zoom modes

○ Triple-tap to toggle○ Triple-tap and hold for

momentary zoom


Features in Kitkat

Global Captioning Preferences

● Available in Android 4.4○ Open caption settings menu from

your application.

Settings.ACTION_CAPTIONING_SETTINGS


Features in Kitkat

Global Captioning Preferences

● Use Videoview API in your applications and use addSubtitleSource() method.

● Captioning Manager API available.


Chrome Browser

● Follow same accessibility guidelines as desktop web○ Provide alt text○ Use ARIA

● Similar to ChromeVox used in desktop Chrome


Just Speak

Accessibility Service to perform major tasks via speech command.

Beta version is released

More info: http://eyes-free.blogspot.com/

http://eyes-free.blogspot.com/


(demo)


What framework providesAndroid applications and sensors

● SMS, Video chats, Videos with Captions● Location aware, GPS, Maps, Places● Proximity● Motion, Accelerometer, Velocity tracker, Light sensor● Environmental and Position sensors

Sensor batching available to reduce power consumption (Introduced in Kitkat).

Read the Android Developer Guide for Sensors

http://developer.android.com/guide/topics/sensors/index.html



Google Play● Paid apps in many Countries● DCB

Developer Console● Countries and currencies ● Statistics



Developer Console● Auto Translate feature● Purchase professional

translations or rely on autotranslate.

Global accessibility● i18n and l10n● Read the Android Developer

Guide for Localization

http://developer.android.com/guide/topics/resources/localization.html





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

http://developer.android.com/design/patterns/accessibility.html


(demo)


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


<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" ... />



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

http://developer.android.com/design/patterns/accessibility.html


<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>



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" .... />


(demo)


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


Logical grouping and ordering


<LinearLayout>….<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" ... /></FolderIcon>….</LinearLayout>


Custom-drawn views

● Use or extend existing classes and interfaces when possible

● Android 4.1 added support for AccessibilityNodeProviders


Custom-drawn views

Use ExploreByTouchHelper. Wraps AccessibilityNodeProviderCompat.You need to implement 5 Abstract methods.

Detail here: http://developer.android.com/reference/android/support/v4/widget/ExploreByTouchHelper.html

http://developer.android.com/reference/android/support/v4/widget/ExploreByTouchHelper.html





Custom-drawn views

Delegate handling of certain events

Implement support for Explore by Touch

Expose information to accessibility services

Provide support for user interaction

Test, ensure feature parity

More details in this I/O talk:https://developers.google.com/events/io/sessions/258451203

https://developers.google.com/events/io/sessions/258451203

https://developers.google.com/events/io/sessions/258451203


Testing and Debugging for Accessibility

For all Android apps

○ Create checklist of what should be tested for Accessibility

○ Check with real simulation○ Test on all supported platforms○ Test on screens and densities

Screens: small, normal, large, xlargeDensities: (low (ldpi), medium (mdpi), high (hdpi), extra high (xhdpi))


Testing and Debugging for Accessibility

For all Android apps● Enable verbose logging for

Accessibility in: Accessibility > TalkBack > Settings > Developer settings

● Android Lint tool


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○ Add captions to videos

● Fix custom components○ Use ExploreByTouchHelper

● Test and Fix


Summary

Good to have:● Augment audio-only prompts

○ Visual cues○ Haptic feedback

● Evaluate sensors● Follow UI guidelines● Reach globally

Read the Android Developer Guide for Accessibility

http://developer.android.com/guide/topics/ui/accessibility/index.html


Thanks and Questions?Send feedback to:[email protected]@gmail.com G+ soniash@sonia1sh

mailto:[email protected]




Technology

Android accessibility till_kitkat_nov2013_andevcon