docs/html/sdk/android-4.0.jd - platform/frameworks/base - Gitiles

 page.title=Android 4.0 Platform
 sdk.platform.version=4.0
 sdk.platform.apiLevel=14
 @jd:body

 <div id="qv-wrapper">
 <div id="qv">

 <h2>In this document</h2>
 <ol>
   <li><a href="#relnotes">Revisions</a></li>
   <li><a href="#api">API Overview</a></li>
   <li><a href="#Honeycomb">Previous APIs</a></li>
   <li><a href="#api-diff">API Differences Report</a></li>
   <li><a href="#api-level">API Level</a></li>
   <li><a href="#apps">Built-in Applications</a></li>
   <li><a href="#locs">Locales</a></li>
   <li><a href="#skins">Emulator Skins</a></li>
 </ol>

 <h2>Reference</h2>
 <ol>
 <li><a
 href="{@docRoot}sdk/api_diff/14/changes.html">API
 Differences Report &raquo;</a> </li>
 </ol>

 </div>
 </div>


 <p><em>API Level:</em>&nbsp;<strong>{@sdkPlatformApiLevel}</strong></p>

 <p>Android 4.0 (Ice Cream Sandwich) is a major platform release that adds new
 capabilities for users and developers. The sections below provide an overview
 of the new features and developer APIs.</p>

 <p>For developers, the Android {@sdkPlatformVersion} platform is available as a
 downloadable component for the Android SDK. The downloadable platform includes
 an Android library and system image, as well as a set of emulator skins and
 more. The downloadable platform includes no external libraries.</p>

 <p>To start developing or testing against Android {@sdkPlatformVersion},
 use the Android SDK Manager to download the platform into your SDK. For more
 information, see <a href="{@docRoot}sdk/adding-components.html">Adding SDK
 Components</a>. If you are new to Android, <a
 href="{@docRoot}sdk/index.html">download the SDK Starter Package</a> first.</p>

 <p class="note"><strong>Reminder:</strong> If you've already published an
 Android application, please test your application on Android {@sdkPlatformVersion} as
 soon as possible to be sure your application provides the best
 experience possible on the latest Android-powered devices.</p>

 <p>For a high-level introduction to the new user and developer features in Android 4.0, see the
 <a href="http://developer.android.com/sdk/android-4.0-highlights.html">Platform Highlights</a>.</p>


 <h2 id="relnotes">Revisions</h2>

 <p>To determine what revision of the Android {@sdkPlatformVersion} platform you
 have installed, refer to the "Installed Packages" listing in the Android SDK Manager.</p>


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   <p><a href="#" onclick="return toggleContent(this)">
     <img src="{@docRoot}assets/images/triangle-opened.png"
 class="toggle-content-img" alt="" />
     Android {@sdkPlatformVersion}, Revision 1</a> <em>(October 2011)</em>
   </a></p>

   <div class="toggle-content-toggleme" style="padding-left:2em;">

 <dl>
 <dt>Initial release. SDK Tools r14 or higher is recommended.</dt>
 </dl>

   </div>
 </div>


 <h2 id="api">API Overview</h2>

 <p>The sections below provide a technical overview of new APIs in Android 4.0.</p>

 <div class="toggle-content closed" style="padding-left:1em;">

   <p><a href="#" onclick="return toggleContent(this)">
     <img src="{@docRoot}assets/images/triangle-closed.png"
 class="toggle-content-img" alt="" />
     <strong>Table of Contents</strong>
   </a></p>

   <div class="toggle-content-toggleme" style="padding-left:2em;">
     <ol class="toc" style="margin-left:-1em">
       <li><a href="#Contacts">Contact Provider</a></li>
       <li><a href="#Calendar">Calendar Provider</a></li>
       <li><a href="#Voicemail">Voicemail Provider</a></li>
       <li><a href="#Camera">Camera</a></li>
       <li><a href="#Multimedia">Multimedia</a></li>
       <li><a href="#Bluetooth">Bluetooth</a></li>
       <li><a href="#AndroidBeam">Android Beam (NDEF Push with NFC)</a></li>
       <li><a href="#WiFiDirect">Wi-Fi Direct</a></li>
       <li><a href="#NetworkUsage">Network Usage</a></li>
       <li><a href="#RenderScript">RenderScript</a></li>
       <li><a href="#A11y">Accessibility</a></li>
       <li><a href="#Enterprise">Enterprise</a></li>
       <li><a href="#Sensors">Device Sensors</a></li>
       <li><a href="#TTS">Text-to-speech Engines</a></li>
       <li><a href="#SpellChecker">Spell Checker Services</a></li>
       <li><a href="#ActionBar">Action Bar</a></li>
       <li><a href="#UI">User Interface and Views</a></li>
       <li><a href="#Properties">Properties</a></li>
       <li><a href="#HwAccel">Hardware Acceleration</a></li>
       <li><a href="#Jni">JNI Changes</a></li>
       <li><a href="#WebKit">WebKit</a></li>
       <li><a href="#Permissions">Permissions</a></li>
       <li><a href="#DeviceFeatures">Device Features</a></li>
     </ol>
   </div>
 </div>


 <h3 id="Contacts">Contact Provider</h3>

 <p>The contact APIs that are defined by the {@link android.provider.ContactsContract} provider have
 been extended to support new features such as a personal profile for the device owner, high
 resolution contact photos, and the ability for users to invite individual contacts to social
 networks that are installed on the device.</p>


 <h4>User Profile</h4>

 <p>Android now includes a personal profile that represents the device owner, as defined by the
 {@link android.provider.ContactsContract.Profile} table.  Social apps that maintain a user identity
 can contribute to the user's profile data by creating a new {@link
 android.provider.ContactsContract.RawContacts} entry within the {@link
 android.provider.ContactsContract.Profile}. That is, raw contacts that represent the device user do
 not belong in the traditional raw contacts table defined by the {@link
 android.provider.ContactsContract.RawContacts} Uri; instead, you must add a profile raw contact in
 the table at {@link android.provider.ContactsContract.Profile#CONTENT_RAW_CONTACTS_URI}. Raw
 contacts in this table are then aggregated into the single user-visible profile labeled "Me".</p>

 <p>Adding a new raw contact for the profile requires the {@link
 android.Manifest.permission#WRITE_PROFILE} permission. Likewise, in order to read from the profile
 table, you must request the {@link android.Manifest.permission#READ_PROFILE} permission. However,
 most apps should need to read the user profile, even when contributing data to the
 profile. Reading the user profile is a sensitive permission and you should expect users to be
 skeptical of apps that request it.</p>


 <h4>Large photos</h4>

 <p>Android now supports high resolution photos for contacts. Now, when you push a photo into a
 contact record, the system processes it into both a 96x96 thumbnail (as it has previously) and a
 256x256 "display photo" that's stored in a new file-based photo store (the exact dimensions that the
 system chooses may vary in the future). You can add a large photo to a contact by putting a large
 photo in the usual {@link android.provider.ContactsContract.CommonDataKinds.Photo#PHOTO} column of a
 data row, which the system will then process into the appropriate thumbnail and display photo
 records.</p>


 <h4>Invite Intent</h4>

 <p>The {@link android.provider.ContactsContract.Intents#INVITE_CONTACT} intent action allows an app
 to invoke an action that indicates the user wants to add a contact to a social network. The app
 receiving the app uses it to invite the specified contact to that
 social network. Most apps will be on the receiving-end of this operation. For example, the
 built-in People app invokes the invite intent when the user selects "Add connection" for a specific
 social app that's listed in a person's contact details.</p>

 <p>To make your app visible as in the "Add connection" list, your app must provide a sync adapter to
 sync contact information from your social network. You must then indicate to the system that your
 app responds to the {@link android.provider.ContactsContract.Intents#INVITE_CONTACT} intent by
 adding the {@code inviteContactActivity} attribute to your app’s sync configuration file, with a
 fully-qualified name of the activity that the system should start when sending the invite intent.
 The activity that starts can then retrieve the URI for the contact in question from the intent’s
 data and perform the necessary work to invite that contact to the network or add the person to the
 user’s connections.</p>

 <p>See the <a href="{@docRoot}resources/samples/SampleSyncAdapter/index.html">Sample Sync
 Adapter</a> app for an example (specifically, see the <a
 href="{@docRoot}resources/samples/SampleSyncAdapter/res/xml-v14/contacts.html">contacts.xml</a>
 file).</p>


 <h4>Contact Usage Feedback</h4>

 <p>The new {@link android.provider.ContactsContract.DataUsageFeedback} APIs allow you to  help track
 how often the user uses particular methods of contacting people, such as how often the user uses
 each phone number or e-mail address. This information helps improve the ranking for each contact
 method associated with each person and provide better suggestions for contacting each person.</p>


 <h3 id="Calendar">Calendar Provider</h3>

 <p>The new calendar APIs allow you to read, add, modify and delete calendars, events, attendees,
 reminders and alerts, which are stored in the Calendar Provider.</p>

 <p>A variety of apps and widgets can use these APIs to read and modify calendar events. However,
 some of the most compelling use cases are sync adapters that synchronize the user's calendar from
 other calendar services with the Calendar Provider, in order to offer a unified location for all the
 user's events. Google Calendar events, for example, are synchronized with the Calendar Provider by
 the Google Calendar Sync Adapter, allowing these events to be viewed with Android's built-in
 Calendar app.</p>

 <p>The data model for calendars and event-related information in the Calendar Provider is
 defined by {@link android.provider.CalendarContract}. All the user’s calendar data is stored in a
 number of tables defined by various subclasses of {@link android.provider.CalendarContract}:</p>

 <ul>
 <li>The {@link android.provider.CalendarContract.Calendars} table holds the calendar-specific
 information. Each row in this table contains the details for a single calendar, such as the name,
 color, sync information, and so on.</li>

 <li>The {@link android.provider.CalendarContract.Events} table holds event-specific information.
 Each row in this table contains the information for a single event, such as the
 event title, location, start time, end time, and so on. The event can occur one time or recur
 multiple times. Attendees, reminders, and extended properties are stored in separate tables and
 use the event’s {@code _ID} to link them with the event.</li>

 <li>The {@link android.provider.CalendarContract.Instances} table holds the start and end time for
 occurrences of an event. Each row in this table represents a single occurrence. For one-time events
 there is a one-to-one mapping of instances to events. For recurring events, multiple rows are
 automatically generated to correspond to the multiple occurrences of that event.</li>

 <li>The {@link android.provider.CalendarContract.Attendees} table holds the event attendee or guest
 information. Each row represents a single guest of an event. It specifies the type of guest the
 person is and the person’s response for the event.</li>

 <li>The {@link android.provider.CalendarContract.Reminders} table holds the alert/notification data.
 Each row represents a single alert for an event. An event can have multiple reminders. The number of
 reminders per event is specified in {@code MAX_REMINDERS}, which is set by the sync adapter that
 owns the given calendar. Reminders are specified in number-of-minutes before the event is
 scheduled and specify an alarm method such as to use an alert, email, or SMS to remind
 the user.</li>

 <li>The {@link android.provider.CalendarContract.ExtendedProperties} table hold opaque data fields
 used by the sync adapter. The provider takes no action with items in this table except to delete
 them when their related events are deleted.</li>
 </ul>

 <p>To access a user’s calendar data with the Calendar Provider, your application must request
 the {@link android.Manifest.permission#READ_CALENDAR} permission (for read access) and
 {@link android.Manifest.permission#WRITE_CALENDAR} (for write access).</p>


 <h4>Event intent</h4>

 <p>If all you want to do is add an event to the user’s calendar, you can use an
 {@link android.content.Intent#ACTION_INSERT} intent with a {@code "vnd.android.cursor.item/event"}
 MIME type to start an activity in the Calendar app that creates new events. Using the intent does
 not require any permission and you can specify event details with the following extras:</p>

 <ul>
   <li>{@link android.provider.CalendarContract.EventsColumns#TITLE Events.TITLE}: Name for the
 event</li>
   <li>{@link
 android.provider.CalendarContract#EXTRA_EVENT_BEGIN_TIME CalendarContract.EXTRA_EVENT_BEGIN_TIME}:
 Event begin time in milliseconds from the
 epoch</li>
   <li>{@link
 android.provider.CalendarContract#EXTRA_EVENT_END_TIME CalendarContract.EXTRA_EVENT_END_TIME}: Event
 end time in milliseconds from the epoch</li>
   <li>{@link android.provider.CalendarContract.EventsColumns#EVENT_LOCATION Events.EVENT_LOCATION}:
 Location of the event</li>
   <li>{@link android.provider.CalendarContract.EventsColumns#DESCRIPTION Events.DESCRIPTION}: Event
 description</li>
   <li>{@link android.content.Intent#EXTRA_EMAIL Intent.EXTRA_EMAIL}: Email addresses of those to
 invite</li>
   <li>{@link android.provider.CalendarContract.EventsColumns#RRULE Events.RRULE}: The recurrence
 rule for the event</li>
   <li>{@link android.provider.CalendarContract.EventsColumns#ACCESS_LEVEL Events.ACCESS_LEVEL}:
 Whether the event is private or public</li>
   <li>{@link android.provider.CalendarContract.EventsColumns#AVAILABILITY Events.AVAILABILITY}:
 Whether the time period of this event allows for other events to be scheduled at the same time</li>
 </ul>


 <h3 id="Voicemail">Voicemail Provider</h3>

 <p>The new voicemail APIs allows applications to add voicemails to a content provider on the device.
 Because the APIs currently do not allow third party apps to read all the voicemails from the system,
 the only third-party apps that should use the voicemail APIs are those that have voicemail to
 deliver to the user. For instance, it’s possible that a user has multiple voicemail sources, such as
 one provided by the phone’s service provider and others from VoIP or other alternative voice
 services. These apps can use the APIs to add their voicemails to the system for quick playback. The
 built-in Phone application presents all voicemails from the Voicemail Provider with a single list.
 Although the system’s Phone application is the only application that can read all the voicemails,
 each application that provides voicemails can read those that it has added to the system (but cannot
 read voicemails from other services).</p>

 <p>The {@link android.provider.VoicemailContract} class defines the content provider for the
 voicemail APIs. The subclasses {@link android.provider.VoicemailContract.Voicemails} and {@link
 android.provider.VoicemailContract.Status} provide tables in which the Voicemail Providers can
 insert voicemail data for storage on the device. For an example of a voicemail provider app, see the
 <a href="{@docRoot}resources/samples/VoicemailProviderDemo/index.html">Voicemail Provider
 Demo</a>.</p>


 <h3 id="Camera">Camera</h3>

 <p>The {@link android.hardware.Camera} class now includes APIs for detecting faces and controlling
 focus and metering areas.</p>


 <h4>Face detection</h4>

 <p>Camera apps can now enhance their abilities with Android’s face detection APIs, which not
 only detect the face of a subject, but also specific facial features, such as the eyes and mouth.
 </p>

 <p>To detect faces in your camera application, you must register a {@link
 android.hardware.Camera.FaceDetectionListener} by calling {@link
 android.hardware.Camera#setFaceDetectionListener setFaceDetectionListener()}. You can then start
 your camera surface and start  detecting faces by calling {@link
 android.hardware.Camera#startFaceDetection}.</p>

 <p>When the system detects one or more faces in the camera scene, it calls the {@link
 android.hardware.Camera.FaceDetectionListener#onFaceDetection onFaceDetection()} callback in your
 implementation of {@link android.hardware.Camera.FaceDetectionListener}, including an array of
 {@link android.hardware.Camera.Face} objects.</p>

 <p>An instance of the {@link android.hardware.Camera.Face} class provides various information about
 the face detected, including:</p>
 <ul>
 <li>A {@link android.graphics.Rect} that specifies the bounds of the face, relative to the camera's
 current field of view</li>
 <li>An integer betwen 1 and 100 that indicates how confident the system is that the object is a
 human face</li>
 <li>A unique ID so you can track multiple faces</li>
 <li>Several {@link android.graphics.Point} objects that indicate where the eyes and mouth are
 located</li>
 </ul>

 <p class="note"><strong>Note:</strong> Face detection may not be supported on some
 devices, so you should check by calling {@link
 android.hardware.Camera.Parameters#getMaxNumDetectedFaces()} and ensure the return
 value is greater than zero. Also, some devices may not support identification of eyes and mouth,
 in which case, those fields in the {@link android.hardware.Camera.Face} object will be null.</p>


 <h4>Focus and metering areas</h4>

 <p>Camera apps can now control the areas that the camera uses for focus and for metering white
 balance
 and auto-exposure. Both features use the new {@link android.hardware.Camera.Area} class to specify
 the region of the camera’s current view that should be focused or metered. An instance of the {@link
 android.hardware.Camera.Area} class defines the bounds of the area with a {@link
 android.graphics.Rect} and the area's weight&mdash;representing the level of importance of that
 area, relative to other areas in consideration&mdash;with an integer.</p>

 <p>Before setting either a focus area or metering area, you should first call {@link
 android.hardware.Camera.Parameters#getMaxNumFocusAreas} or {@link
 android.hardware.Camera.Parameters#getMaxNumMeteringAreas}, respectively. If these return zero, then
 the device does not support the corresponding feature.</p>

 <p>To specify the focus or metering areas to use, simply call {@link
 android.hardware.Camera.Parameters#setFocusAreas setFocusAreas()} or {@link
 android.hardware.Camera.Parameters#setFocusAreas setMeteringAreas()}. Each take a {@link
 java.util.List} of {@link android.hardware.Camera.Area} objects that indicate the areas to consider
 for focus or metering. For example, you might implement a feature that allows the user to set the
 focus area by touching an area of the preview, which you then translate to an {@link
 android.hardware.Camera.Area} object and request that the camera focus on that area of the scene.
 The focus or exposure in that area will continually update as the scene in the area changes.</p>


 <h4>Continuous auto focus for photos</h4>

 <p>You can now enable continuous auto focusing (CAF) when taking photos. To enable CAF in your
 camera app, pass {@link android.hardware.Camera.Parameters#FOCUS_MODE_CONTINUOUS_PICTURE}
 to {@link android.hardware.Camera.Parameters#setFocusMode setFocusMode()}. When ready to capture
 a photo, call {@link android.hardware.Camera#autoFocus autoFocus()}. Your {@link
 android.hardware.Camera.AutoFocusCallback} immediately receives a callback to indicate whether
 focus was acheived. To resume CAF after receiving the callback, you must call {@link
 android.hardware.Camera#cancelAutoFocus()}.</p>

 <p class="note"><strong>Note:</strong> Continuous auto focus is also supported when capturing
 video, using {@link android.hardware.Camera.Parameters#FOCUS_MODE_CONTINUOUS_VIDEO}, which was
 added in API level 9.</p>


 <h4>Other camera features</h4>

 <ul>
 <li>While recording video, you can now call {@link android.hardware.Camera#takePicture
 takePicture()} to save a photo without interrupting the video session. Before doing so, you should
 call {@link android.hardware.Camera.Parameters#isVideoSnapshotSupported} to be sure the hardware
 supports it.</li>

 <li>You can now lock auto exposure and white balance with {@link
 android.hardware.Camera.Parameters#setAutoExposureLock setAutoExposureLock()} and {@link
 android.hardware.Camera.Parameters#setAutoWhiteBalanceLock setAutoWhiteBalanceLock()} to prevent
 these properties from changing.</li>

 <li>You can now call {@link android.hardware.Camera#setDisplayOrientation
 setDisplayOrientation()} while the camera preview is running. Previously, you could call this
 only before beginning the preview, but you can now change the orientation at any time.</li>
 </ul>


 <h4>Camera broadcast intents</h4>

 <ul>
 <li>{@link android.hardware.Camera#ACTION_NEW_PICTURE Camera.ACTION_NEW_PICTURE}:
 This indicates that the user has captured a new photo. The built-in Camera app invokes this
 broadcast after a photo is captured and third-party camera apps should also broadcast this intent
 after capturing a photo.</li>
 <li>{@link android.hardware.Camera#ACTION_NEW_VIDEO Camera.ACTION_NEW_VIDEO}:
 This indicates that the user has captured a new video. The built-in Camera app invokes this
 broadcast after a video is recorded and third-party camera apps should also broadcast this intent
 after capturing a video.</li>
 </ul>


 <h3 id="Multimedia">Multimedia</h3>

 <p>Android 4.0 adds several new APIs for applications that interact with media such as photos,
 videos, and music.</p>


 <h4>Media player</h4>

 <ul>
 <li>Streaming online media from {@link android.media.MediaPlayer} now requires the {@link
 android.Manifest.permission#INTERNET} permission. If you use {@link android.media.MediaPlayer} to
 play content from the Internet, be sure to add the {@link android.Manifest.permission#INTERNET}
 permission to your manifest or else your media playback will not work beginning with Android
 4.0.</li>

 <li>{@link android.media.MediaPlayer#setSurface(Surface) setSurface()} allows you define a {@link
 android.view.Surface} to behave as the video sink.</li>

 <li>{@link android.media.MediaPlayer#setDataSource(Context,Uri,Map) setDataSource()} allows you to
 send additional HTTP headers with your request, which can be useful for HTTP(S) live streaming</li>

 <li>HTTP(S) live streaming now respects HTTP cookies across requests</li>
 </ul>


 <h4>Media types</h4>

 <p>Android 4.0 adds support for:</p>
 <ul>
 <li>HTTP/HTTPS live streaming protocol version 3 </li>
 <li>ADTS raw AAC audio encoding</li>
 <li>WEBP images</li>
 <li>Matroska video</li>
 </ul>
 <p>For more info, see <a href="{@docRoot}guide/appendix/media-formats.html">Supported Media
 Formats</a>.</p>


 <h4>Remote control client</h4>

 <p>The new {@link android.media.RemoteControlClient} allows media players to enable playback
 controls from remote control clients such as the device lock screen. Media players can also expose
 information about the media currently playing for display on the remote control, such as track
 information and album art.</p>

 <p>To enable remote control clients for your media player, instantiate a {@link
 android.media.RemoteControlClient} with its constructor, passing it a {@link
 android.app.PendingIntent} that broadcasts {@link
 android.content.Intent#ACTION_MEDIA_BUTTON}. The intent must also declare the explicit {@link
 android.content.BroadcastReceiver} component in your app that handles the {@link
 android.content.Intent#ACTION_MEDIA_BUTTON} event.</p>

 <p>To declare which media control inputs your player can handle, you must call {@link
 android.media.RemoteControlClient#setTransportControlFlags setTransportControlFlags()} on your
 {@link android.media.RemoteControlClient}, passing a set of {@code FLAG_KEY_MEDIA_*} flags, such as
 {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_PREVIOUS} and {@link
 android.media.RemoteControlClient#FLAG_KEY_MEDIA_NEXT}.</p>

 <p>You must then register your {@link android.media.RemoteControlClient} by passing it to {@link
 android.media.AudioManager#registerRemoteControlClient MediaManager.registerRemoteControlClient()}.
 Once registered, the broadcast receiver you declared when you instantiated the {@link
 android.media.RemoteControlClient} will receive {@link android.content.Intent#ACTION_MEDIA_BUTTON}
 events when a button is pressed from a remote control. The intent you receive includes the {@link
 android.view.KeyEvent} for the media key pressed, which you can retrieve from the intent with {@link
 android.content.Intent#getParcelableExtra getParcelableExtra(Intent.EXTRA_KEY_EVENT)}.</p>

 <p>To display information on the remote control about the media playing, call {@link
 android.media.RemoteControlClient#editMetadata editMetaData()} and add metadata to the returned
 {@link android.media.RemoteControlClient.MetadataEditor}. You can supply a bitmap for media artwork,
 numerical information such as elapsed time, and text information such as the track title. For
 information on available keys see the {@code METADATA_KEY_*} flags in {@link
 android.media.MediaMetadataRetriever}.</p>

 <p>For a sample implementation, see the <a
 href="{@docRoot}resources/samples/RandomMusicPlayer/index.html">Random Music Player</a>, which
 provides compatibility logic such that it enables the remote control client on Android 4.0
 devices while continuing to support devices back to Android 2.1.</p>


 <h4>Media Effects</h4>

 <p>A new media effects framework allows you to apply a variety of visual effects to images and
 videos. For example, image effects allow you to easily fix red-eye, convert an image to grayscale,
 adjust brightness, adjust saturation, rotate an image, apply a fisheye effect, and much more. The
 system performs all effects processing on the GPU to obtain maximum performance.</p>

 <p>For maximum performance, effects are applied directly to OpenGL textures, so your application
 must have a valid OpenGL context before it can use the effects APIs. The textures to which you apply
 effects may be from bitmaps, videos or even the camera. However, there are certain restrictions that
 textures must meet:</p>
 <ol>
 <li>They must be bound to a {@link android.opengl.GLES20#GL_TEXTURE_2D} texture image</li>
 <li>They must contain at least one mipmap level</li>
 </ol>

 <p>An {@link android.media.effect.Effect} object defines a single media effect that you can apply to
 an image frame. The basic workflow to create an {@link android.media.effect.Effect} is:</p>

 <ol>
 <li>Call {@link android.media.effect.EffectContext#createWithCurrentGlContext
 EffectContext.createWithCurrentGlContext()} from your OpenGL ES 2.0 context.</li>
 <li>Use the returned {@link android.media.effect.EffectContext} to call {@link
 android.media.effect.EffectContext#getFactory EffectContext.getFactory()}, which returns an instance
 of {@link android.media.effect.EffectFactory}.</li>
 <li>Call {@link android.media.effect.EffectFactory#createEffect createEffect()}, passing it an
 effect name from @link android.media.effect.EffectFactory}, such as {@link
 android.media.effect.EffectFactory#EFFECT_FISHEYE} or {@link
 android.media.effect.EffectFactory#EFFECT_VIGNETTE}.</li>
 </ol>

 <p>Not all devices support all effects, so you must first check if the desired effect is supported
 by calling {@link android.media.effect.EffectFactory#isEffectSupported isEffectSupported()}.</p>

 <p>You can adjust an effect’s parameters by calling {@link android.media.effect.Effect#setParameter
 setParameter()} and passing a parameter name and parameter value. Each type of effect accepts
 different parameters, which are documented with the effect name. For example, {@link
 android.media.effect.EffectFactory#EFFECT_FISHEYE} has one parameter for the {@code scale} of the
 distortion.</p>

 <p>To apply an effect on a texture, call {@link android.media.effect.Effect#apply apply()} on the
 {@link
 android.media.effect.Effect} and pass in the input texture, it’s width and height, and the output
 texture. The input texture  must be bound to a {@link android.opengl.GLES20#GL_TEXTURE_2D} texture
 image (usually done by calling the {@link android.opengl.GLES20#glTexImage2D glTexImage2D()}
 function). You may provide multiple mipmap levels. If the output texture has not been bound to a
 texture image, it will be automatically bound by the effect as a {@link
 android.opengl.GLES20#GL_TEXTURE_2D} and with one mipmap level (0), which will have the same
 size as the input.</p>


 <h3 id="Bluetooth">Bluetooth</h3>

 <p>Android now supports Bluetooth Health Profile devices, so you can create applications that use
 Bluetooth to communicate with health devices that support Bluetooth, such as heart-rate monitors,
 blood meters, thermometers, and scales.</p>

 <p>Similar to regular headset and A2DP profile devices, you must call {@link
 android.bluetooth.BluetoothAdapter#getProfileProxy getProfileProxy()} with a {@link
 android.bluetooth.BluetoothProfile.ServiceListener} and the {@link
 android.bluetooth.BluetoothProfile#HEALTH} profile type to establish a connection with the profile
 proxy object.</p>

 <p>Once you’ve acquired the Health Profile proxy (the {@link android.bluetooth.BluetoothHealth}
 object), connecting to and communicating with paired health devices involves the following new
 Bluetooth classes:</p>
 <ul>
 <li>{@link android.bluetooth.BluetoothHealthCallback}: You must extend this class and implement the
 callback methods to receive updates about changes in the application’s registration state and
 Bluetooth channel state.</li>
 <li>{@link android.bluetooth.BluetoothHealthAppConfiguration}: During callbacks to your {@link
 android.bluetooth.BluetoothHealthCallback}, you’ll receive an instance of this object, which
 provides configuration information about the available Bluetooth health device, which you must use
 to perform various operations such as initiate and terminate connections with the {@link
 android.bluetooth.BluetoothHealth} APIs.</li>
 </ul>

 <p>For more information about using the Bluetooth Health Profile, see the documentation for {@link
 android.bluetooth.BluetoothHealth}.</p>


 <h3 id="AndroidBeam">Android Beam (NDEF Push with NFC)</h3>

 <p>Android Beam is a new NFC feature that allows you to send NDEF messages from one device to
 another (a process also known as “NDEF Push"). The data transfer is initiated when two
 Android-powered devices that support Android Beam are in close proximity (about 4 cm), usually with
 their backs touching. The data inside the NDEF message can contain any data that you wish to share
 between devices. For example, the People app shares contacts, YouTube shares videos, and Browser
 shares URLs using Android Beam.</p>

 <p>To transmit data between devices using Android Beam, you need to create an {@link
 android.nfc.NdefMessage} that contains the information you want to share while your activity is in
 the foreground. You must then pass the {@link android.nfc.NdefMessage} to the system in one of two
 ways:</p>

 <ul>
 <li>Define a single {@link android.nfc.NdefMessage} to push while in the activity:
 <p>Call {@link android.nfc.NfcAdapter#setNdefPushMessage setNdefPushMessage()} at any time to set
 the message you want to send. For instance, you might call this method and pass it your {@link
 android.nfc.NdefMessage} during your activity’s {@link android.app.Activity#onCreate onCreate()}
 method. Then, whenever Android Beam is activated with another device while the activity is in the
 foreground, the system sends the {@link android.nfc.NdefMessage} to the other device.</p></li>

 <li>Define the {@link android.nfc.NdefMessage} to push at the time that Android Beam is initiated:
 <p>Implement {@link android.nfc.NfcAdapter.CreateNdefMessageCallback}, in which your
 implementation of the {@link
 android.nfc.NfcAdapter.CreateNdefMessageCallback#createNdefMessage createNdefMessage()}
 method returns the {@link android.nfc.NdefMessage} you want to send. Then pass the {@link
 android.nfc.NfcAdapter.CreateNdefMessageCallback} implementation to {@link
 android.nfc.NfcAdapter#setNdefPushMessageCallback setNdefPushMessageCallback()}.</p>
 <p>In this case, when Android Beam is activated with another device while your activity is in the
 foreground, the system calls {@link
 android.nfc.NfcAdapter.CreateNdefMessageCallback#createNdefMessage createNdefMessage()} to retrieve
 the {@link android.nfc.NdefMessage} you want to send. This allows you to define the {@link
 android.nfc.NdefMessage} to deliver only once Android Beam is initiated, in case the contents
 of the message might vary throughout the life of the activity.</p></li>
 </ul>

 <p>In case you want to run some specific code once the system has successfully delivered your NDEF
 message to the other device, you can implement {@link
 android.nfc.NfcAdapter.OnNdefPushCompleteCallback} and set it with {@link
 android.nfc.NfcAdapter#setOnNdefPushCompleteCallback setNdefPushCompleteCallback()}. The system will
 then call {@link android.nfc.NfcAdapter.OnNdefPushCompleteCallback#onNdefPushComplete
 onNdefPushComplete()} when the message is delivered.</p>

 <p>On the receiving device, the system dispatches NDEF Push messages in a similar way to regular NFC
 tags. The system invokes an intent with the {@link android.nfc.NfcAdapter#ACTION_NDEF_DISCOVERED}
 action to start an activity, with either a URL or a MIME type set according to the first {@link
 android.nfc.NdefRecord} in the {@link android.nfc.NdefMessage}. For the activity you want to
 respond, you can declare intent filters for the URLs or MIME types your app cares about. For more
 information about Tag Dispatch see the <a
 href="{@docRoot}guide/topics/nfc/index.html#dispatch">NFC</a> developer guide.</p>

 <p>If you want your {@link android.nfc.NdefMessage} to carry a URI, you can now use the convenience
 method {@link android.nfc.NdefRecord#createUri createUri} to construct a new {@link
 android.nfc.NdefRecord} based on either a string or a {@link android.net.Uri} object. If the URI is
 a special format that you want your application to also receive during an Android Beam event, you
 should create an intent filter for your activity using the same URI scheme in order to receive the
 incoming NDEF message.</p>

 <p>You should also pass an “Android application record" with your {@link android.nfc.NdefMessage} in
 order to guarantee that your application handles the incoming NDEF message, even if other
 applications filter for the same intent action. You can create an Android application record by
 calling {@link android.nfc.NdefRecord#createApplicationRecord createApplicationRecord()}, passing it
 your application’s package name. When the other device receives the NDEF message with the
 application record and multiple applications contain activities that handle the specified intent,
 the system always delivers the message to the activity in your application (based on the matching
 application record). If the target device does not currently have your application installed, the
 system uses the Android application record to launch Android Market and take the user to the
 application in order to install it.</p>

 <p>If your application doesn’t use NFC APIs to perform NDEF Push messaging, then Android provides a
 default behavior: When your application is in the foreground on one device and Android Beam is
 invoked with another Android-powered device, then the other device receives an NDEF message with an
 Android application record that identifies your application. If the receiving device has the
 application installed, the system launches it; if it’s not installed, Android Market opens and takes
 the user to your application in order to install it.</p>

 <p>For some example code, see the <a
 href="{@docRoot}resources/samples/AndroidBeamDemo/src/com/example/android/beam/Beam.html">Android
 Beam Demo</a> sample app.</p>


 <h3 id="WiFiDirect">Wi-Fi Direct</h3>

 <p>Android now supports Wi-Fi Direct for peer-to-peer (P2P) connections between Android-powered
 devices and other device types without a hotspot or Internet connection. The Android framework
 provides a set of Wi-Fi P2P APIs that allow you to discover and connect to other devices when each
 device supports Wi-Fi Direct, then communicate over a speedy connection across distances much longer
 than a Bluetooth connection.</p>

 <p>A new package, {@link android.net.wifi.p2p}, contains all the APIs for performing peer-to-peer
 connections with Wi-Fi. The primary class you need to work with is {@link
 android.net.wifi.p2p.WifiP2pManager}, which you can acquire by calling {@link
 android.app.Activity#getSystemService getSystemService(WIFI_P2P_SERVICE)}. The {@link
 android.net.wifi.p2p.WifiP2pManager} includes APIs that allow you to:</p>
 <ul>
 <li>Initialize your application for P2P connections by calling {@link
 android.net.wifi.p2p.WifiP2pManager#initialize initialize()}</li>

 <li>Discover nearby devices by calling {@link android.net.wifi.p2p.WifiP2pManager#discoverPeers
 discoverPeers()}</li>

 <li>Start a P2P connection by calling {@link android.net.wifi.p2p.WifiP2pManager#connect
 connect()}</li>
 <li>And more</li>
 </ul>

 <p>Several other interfaces and classes are necessary as well, such as:</p>
 <ul>
 <li>The {@link android.net.wifi.p2p.WifiP2pManager.ActionListener} interface allows you to receive
 callbacks when an operation such as discovering peers or connecting to them succeeds or fails.</li>

 <li>{@link android.net.wifi.p2p.WifiP2pManager.PeerListListener} interface allows you to receive
 information about discovered peers. The callback provides a {@link
 android.net.wifi.p2p.WifiP2pDeviceList}, from which you can retrieve a {@link
 android.net.wifi.p2p.WifiP2pDevice} object for each device within range and get information such as
 the device name, address, device type, the WPS configurations the device supports, and more.</li>

 <li>The {@link android.net.wifi.p2p.WifiP2pManager.GroupInfoListener} interface allows you to
 receive information about a P2P group. The callback provides a {@link
 android.net.wifi.p2p.WifiP2pGroup} object, which provides group information such as the owner, the
 network name, and passphrase.</li>

 <li>{@link android.net.wifi.p2p.WifiP2pManager.ConnectionInfoListener} interface allows you to
 receive information about the current connection. The callback provides a {@link
 android.net.wifi.p2p.WifiP2pInfo} object, which has information such as whether a group has been
 formed and who is the group owner.</li>
 </ul>

 <p>In order to use the Wi-Fi P2P APIs, your app must request the following user permissions:</p>
 <ul>
 <li>{@link android.Manifest.permission#ACCESS_WIFI_STATE}</li>
 <li>{@link android.Manifest.permission#CHANGE_WIFI_STATE}</li>
 <li>{@link android.Manifest.permission#INTERNET} (although your app doesn’t technically connect
 to the Internet, communicating to Wi-Fi Direct peers with standard java sockets requires Internet
 permission).</li>
 </ul>

 <p>The Android system also broadcasts several different actions during certain Wi-Fi P2P events:</p>
 <ul>
 <li>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_CONNECTION_CHANGED_ACTION}: The P2P
 connection state has changed. This carries {@link
 android.net.wifi.p2p.WifiP2pManager#EXTRA_WIFI_P2P_INFO} with a {@link
 android.net.wifi.p2p.WifiP2pInfo} object and {@link
 android.net.wifi.p2p.WifiP2pManager#EXTRA_NETWORK_INFO} with a {@link android.net.NetworkInfo}
 object.</li>

 <li>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_STATE_CHANGED_ACTION}: The P2P state has
 changed between enabled and disabled. It carries {@link
 android.net.wifi.p2p.WifiP2pManager#EXTRA_WIFI_STATE} with either {@link
 android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_STATE_DISABLED} or {@link
 android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_STATE_ENABLED}</li>

 <li>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_PEERS_CHANGED_ACTION}: The list of peer
 devices has changed.</li>

 <li>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_THIS_DEVICE_CHANGED_ACTION}: The details for
 this device have changed.</li>
 </ul>

 <p>See the  {@link android.net.wifi.p2p.WifiP2pManager} documentation for more information. Also
 look at the <a href="{@docRoot}resources/samples/WiFiDirectDemo/index.html">Wi-Fi Direct Demo</a>
 sample application.</p>


 <h3 id="NetworkUsage">Network Usage</h3>

 <p>Android 4.0 gives users precise visibility of how much network data their applications are using.
 The Settings app provides controls that allow users to manage set limits for network data usage and
 even disable the use of background data for individual apps. In order to avoid users disabling your
 app’s access to data from the background, you should develop strategies to use use the data
 connection efficiently and adjust your usage depending on the type of connection available.</p>

 <p>If your application performs a lot of network transactions, you should provide user settings that
 allow users to control your app’s data habits, such as how often your app syncs data, whether to
 perform uploads/downloads only when on Wi-Fi, whether to use data while roaming, etc. With these
 controls available to them, users are much less likely to disable your app’s access to data when
 they approach their limits, because they can instead precisely control how much data your app uses.
 If you provide a preference activity with these settings, you should include in its manifest
 declaration an intent filter for the {@link android.content.Intent#ACTION_MANAGE_NETWORK_USAGE}
 action. For example:</p>

 <pre>
 &lt;activity android:name="DataPreferences" android:label="@string/title_preferences">
     &lt;intent-filter>
        &lt;action android:name="android.intent.action.MANAGE_NETWORK_USAGE" />
        &lt;category android:name="android.intent.category.DEFAULT" />
     &lt;/intent-filter>
 &lt;/activity>
 </pre>

 <p>This intent filter indicates to the system that this is the activity that controls your
 application’s data usage. Thus, when the user inspects how much data your app is using from the
 Settings app, a “View application settings" button is available that launches your
 preference activity so the user can refine how much data your app uses.</p>

 <p>Also beware that {@link android.net.ConnectivityManager#getBackgroundDataSetting()} is now
 deprecated and always returns true&mdash;use  {@link
 android.net.ConnectivityManager#getActiveNetworkInfo()} instead. Before you attempt any network
 transactions, you should always call {@link android.net.ConnectivityManager#getActiveNetworkInfo()}
 to get the {@link android.net.NetworkInfo} that represents the current network and query {@link
 android.net.NetworkInfo#isConnected()} to check whether the device has a
 connection. You can then check other connection properties, such as whether the device is
 roaming or connected to Wi-Fi.</p>


 <h3 id="RenderScript">RenderScript</h3>

 <p>Three major features have been added to RenderScript:</p>

 <ul>
   <li>Off-screen rendering to a framebuffer object</li>
   <li>Rendering inside a view</li>
   <li>RS for each from the framework APIs</li>
 </ul>

 <p>The {@link android.renderscript.Allocation} class now supports a {@link
 android.renderscript.Allocation#USAGE_GRAPHICS_RENDER_TARGET} memory space, which allows you to
 render things directly into the {@link android.renderscript.Allocation} and use it as a framebuffer
 object.</p>

 <p>{@link android.renderscript.RSTextureView} provides a means to display RenderScript graphics
 inside of a {@link android.view.View},  unlike {@link android.renderscript.RSSurfaceView}, which
 creates a separate window. This key difference allows you to do things such as move, transform, or
 animate an {@link android.renderscript.RSTextureView} as well as draw RenderScript graphics inside
 a view that lies within an activity layout.</p>

 <p>The {@link android.renderscript.Script#forEach Script.forEach()} method allows you to call
 RenderScript compute scripts from the VM level and have them automatically delegated to available
 cores on the device. You do not use this method directly, but any compute RenderScript that you
 write will have a {@link android.renderscript.Script#forEach forEach()}  method that you can call in
 the reflected RenderScript class. You can call the reflected {@link
 android.renderscript.Script#forEach forEach()} method by passing in an input {@link
 android.renderscript.Allocation} to process, an output {@link android.renderscript.Allocation} to
 write the result to, and a {@link android.renderscript.FieldPacker} data structure in case the
 RenderScript needs more information. Only one of the {@link android.renderscript.Allocation}s is
 necessary and the data structure is optional.</p>


 <h3 id="A11y">Accessibility</h3>

 <p>Android 4.0 improves accessibility for sight-impaired users with new explore-by-touch mode
 and extended APIs that allow you to provide more information about view content or
 develop advanced accessibility services.</p>


 <h4>Explore-by-touch mode</h4>

 <p>Users with vision loss can now explore the screen by touching and dragging a finger across the
 screen to hear voice descriptions of the content. Because the explore-by-touch mode works like a
 virtual cursor, it allows screen readers to identify the descriptive text the same way that screen
 readers can when the user navigates with a d-pad or trackball&mdash;by reading information provided
 by {@link android.R.attr#contentDescription android:contentDescription} and {@link
 android.view.View#setContentDescription setContentDescription()} upon a simulated "hover" event. So,
 consider this is a reminder that you should provide descriptive text for the views in your
 application, especially for {@link android.widget.ImageButton}, {@link android.widget.EditText},
 {@link android.widget.ImageView} and other widgets that might not naturally contain descriptive
 text.</p>


 <h4>Accessibility for views</h4>

 <p>To enhance the information available to accessibility services such as screen readers, you can
 implement new callback methods for accessibility events in your custom {@link
 android.view.View} components.</p>

 <p>It's important to first note that the behavior of the {@link
 android.view.View#sendAccessibilityEvent sendAccessibilityEvent()} method has changed in Android
 4.0. As with previous version of Android, when the user enables accessibility services on the device
 and an input event such as a click or hover occurs, the respective view is notified with a call to
 {@link android.view.View#sendAccessibilityEvent sendAccessibilityEvent()}. Previously, the
 implementation of {@link android.view.View#sendAccessibilityEvent sendAccessibilityEvent()} would
 initialize an {@link android.view.accessibility.AccessibilityEvent} and send it to {@link
 android.view.accessibility.AccessibilityManager}. The new behavior involves some additional callback
 methods that allow the view and its parents to add more contextual information to the event:
 <ol>
   <li>When invoked, the {@link
 android.view.View#sendAccessibilityEvent sendAccessibilityEvent()} and {@link
 android.view.View#sendAccessibilityEventUnchecked sendAccessibilityEventUnchecked()} methods defer
 to {@link android.view.View#onInitializeAccessibilityEvent onInitializeAccessibilityEvent()}.
   <p>Custom implementations of {@link android.view.View} might want to implement {@link
 android.view.View#onInitializeAccessibilityEvent onInitializeAccessibilityEvent()} to
 attach additional accessibility information to the {@link
 android.view.accessibility.AccessibilityEvent}, but should also call the super implementation to
 provide default information such as the standard content description, item index, and more.
 However, you should not add additional text content in this callback&mdash;that happens
 next.</p></li>
   <li>Once initialized, if the event is one of several types that should be populated with text
 information, the view then receives a call to {@link
 android.view.View#dispatchPopulateAccessibilityEvent dispatchPopulateAccessibilityEvent()}, which
 defers to the {@link android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()}
 callback.
   <p>Custom implementations of {@link android.view.View} should usually implement {@link
 android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()} to add additional
 text content to the {@link android.view.accessibility.AccessibilityEvent} if the {@link
 android.R.attr#contentDescription android:contentDescription} text is missing or
 insufficient. To add more text description to the
 {@link android.view.accessibility.AccessibilityEvent}, call {@link
 android.view.accessibility.AccessibilityEvent#getText()}.{@link java.util.List#add add()}.</p>
 </li>
   <li>At this point, the {@link android.view.View} passes the event up the view hierarchy by calling
 {@link android.view.ViewGroup#requestSendAccessibilityEvent requestSendAccessibilityEvent()} on the
 parent view. Each parent view then has the chance to augment the accessibility information by
 adding an {@link android.view.accessibility.AccessibilityRecord}, until it
 ultimately reaches the root view, which sends the event to the {@link
 android.view.accessibility.AccessibilityManager} with {@link
 android.view.accessibility.AccessibilityManager#sendAccessibilityEvent
 sendAccessibilityEvent()}.</li>
 </ol>

 <p>In addition to the new methods above, which are useful when extending the {@link
 android.view.View} class, you can also intercept these event callbacks on any {@link
 android.view.View} by extending {@link
 android.view.View.AccessibilityDelegate AccessibilityDelegate} and setting it on the view with
 {@link android.view.View#setAccessibilityDelegate setAccessibilityDelegate()}.
 When you do, each accessibility method in the view defers the call to the corresponding method in
 the delegate. For example, when the view receives a call to {@link
 android.view.View#onPopulateAccessibilityEvent onPopulateAccessibilityEvent()}, it passes it to the
 same method in the {@link android.view.View.AccessibilityDelegate}. Any methods not handled by
 the delegate are given right back to the view for default behavior. This allows you to override only
 the methods necessary for any given view without extending the {@link android.view.View} class.</p>


 <p>If you want to maintain compatibility with Android versions prior to 4.0, while also supporting
 the new the accessibility APIs, you can do so with the latest version of the <em>v4 support
 library</em> (in <a href="{@docRoot}sdk/compatibility-library.html">Compatibility Package, r4</a>)
 using a set of utility classes that provide the new accessibility APIs in a backward-compatible
 design.</p>


 <h4>Accessibility services</h4>

 <p>If you're developing an accessibility service, the information about various accessibility events
 has been significantly expanded to enable more advanced accessibility feedback for users. In
 particular, events are generated based on view composition, providing better context information and
 allowing accessibility services to traverse view hierarchies to get additional view information and
 deal with special cases.</p>

 <p>If you're developing an accessibility service (such as a screen reader), you can access
 additional content information and traverse view hierarchies with the following procedure:</p>
 <ol>
 <li>Upon receiving an {@link android.view.accessibility.AccessibilityEvent} from an application,
 call the {@link android.view.accessibility.AccessibilityEvent#getRecord(int)
 AccessibilityEvent.getRecord()} to retrieve a specific {@link
 android.view.accessibility.AccessibilityRecord} (there may be several records attached to the
 event).</li>

 <li>From either {@link android.view.accessibility.AccessibilityEvent} or an individual {@link
 android.view.accessibility.AccessibilityRecord}, you can call {@link
 android.view.accessibility.AccessibilityRecord#getSource() getSource()} to retrieve a {@link
 android.view.accessibility.AccessibilityNodeInfo} object.
   <p>An {@link android.view.accessibility.AccessibilityNodeInfo} represents a single node
 of the window content in a format that allows you to query accessibility information about that
 node. The {@link android.view.accessibility.AccessibilityNodeInfo} object returned from {@link
 android.view.accessibility.AccessibilityEvent} describes the event source, whereas the source from
 an {@link android.view.accessibility.AccessibilityRecord} describes the predecessor of the event
 source.</p></li>

 <li>With the {@link android.view.accessibility.AccessibilityNodeInfo}, you can query information
 about it, call {@link
 android.view.accessibility.AccessibilityNodeInfo#getParent getParent()} or {@link
 android.view.accessibility.AccessibilityNodeInfo#getChild getChild()} to traverse the view
 hierarchy, and even add child views to the node.</li>
 </ol>

 <p>In order for your application to publish itself to the system as an accessibility service, it
 must declare an XML configuration file that corresponds to {@link
 android.accessibilityservice.AccessibilityServiceInfo}. For more information about creating an
 accessibility service, see {@link
 android.accessibilityservice.AccessibilityService} and {@link
 android.accessibilityservice.AccessibilityService#SERVICE_META_DATA
 SERVICE_META_DATA} for information about the XML configuration.</p>


 <h4>Other accessibility APIs</h4>

 <p>If you're interested in the device's accessibility state, the {@link
 android.view.accessibility.AccessibilityManager} has some new APIs such as:</p>
 <ul>
   <li>{@link android.view.accessibility.AccessibilityManager.AccessibilityStateChangeListener}
 is an interface that allows you to receive a callback whenever accessibility is enabled or
 disabled.</li>
   <li>{@link android.view.accessibility.AccessibilityManager#getEnabledAccessibilityServiceList
     getEnabledAccessibilityServiceList()} provides information about which accessibility services
     are currently enabled.</li>
   <li>{@link android.view.accessibility.AccessibilityManager#isTouchExplorationEnabled()} tells
   you whether the explore-by-touch mode is enabled.</li>
 </ul>


 <h3 id="Enterprise">Enterprise</h3>

 <p>Android 4.0 expands the capabilities for enterprise application with the following features.</p>

 <h4>VPN services</h4>

 <p>The new {@link android.net.VpnService} allows applications to build their own VPN (Virtual
 Private Network), running as a {@link android.app.Service}. A VPN service creates an interface for a
 virtual network with its own address and routing rules and performs all reading and writing with a
 file descriptor.</p>

 <p>To create a VPN service, use {@link android.net.VpnService.Builder}, which allows you to specify
 the network address, DNS server, network route, and more. When complete, you can establish the
 interface by calling {@link android.net.VpnService.Builder#establish()}, which returns a {@link
 android.os.ParcelFileDescriptor}. </p>

 <p>Because  a VPN service can intercept packets, there are security implications.  As such, if you
 implement {@link android.net.VpnService}, then your service must require the {@link
 android.Manifest.permission#BIND_VPN_SERVICE} to ensure that only the system can bind to it (only
 the system is granted this permission&mdash;apps cannot request it). To then use your VPN service,
 users must manually enable it in the system settings.</p>


 <h4>Device restrictions</h4>

 <p>Applications that manage the device restrictions can now disable the camera using {@link
 android.app.admin.DevicePolicyManager#setCameraDisabled setCameraDisabled()} and the {@link
 android.app.admin.DeviceAdminInfo#USES_POLICY_DISABLE_CAMERA} property (applied with a {@code
 &lt;disable-camera /&gt;} element in the policy configuration file).</p>


 <h4>Certificate management</h4>

 <p>The new {@link android.security.KeyChain} class provides APIs that allow you to import and access
 certificates in the system key store. Certificates streamline the installation of both client
 certificates (to validate the identity of the user) and certificate authority certificates (to
 verify server identity). Applications such as web browsers or email clients can access the installed
 certificates to authenticate users to servers. See the {@link android.security.KeyChain}
 documentation for more information.</p>


 <h3 id="Sensors">Device Sensors</h3>

 <p>Two new sensor types have been added in Android 4.0:</p>

 <ul>
   <li>{@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE}: A temperature sensor that provides
 the ambient (room) temperature in degrees Celsius.</li>
   <li>{@link android.hardware.Sensor#TYPE_RELATIVE_HUMIDITY}: A humidity sensor that provides the
 relative ambient (room) humidity as a percentage.</li>
 </ul>

 <p>If a device has both {@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE} and  {@link
 android.hardware.Sensor#TYPE_RELATIVE_HUMIDITY} sensors, you can use them to calculate the dew point
 and the absolute humidity.</p>

 <p>The previous temperature sensor, {@link android.hardware.Sensor#TYPE_TEMPERATURE}, has been
 deprecated. You should use the {@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE} sensor
 instead.</p>

 <p>Additionally, Android’s three synthetic sensors have been improved so they now have lower latency
 and smoother output. These sensors include the gravity sensor ({@link
 android.hardware.Sensor#TYPE_GRAVITY}), rotation vector sensor ({@link
 android.hardware.Sensor#TYPE_ROTATION_VECTOR}), and linear acceleration sensor ({@link
 android.hardware.Sensor#TYPE_LINEAR_ACCELERATION}). The improved sensors rely on the gyroscope
 sensor to improve their output, so the sensors appear only on devices that have a gyroscope.</p>


 <h3 id="TTS">Text-to-speech Engines</h3>

 <p>Android’s text-to-speech (TTS) APIs have been significantly extended to allow applications to
 more easily implement custom TTS engines, while applications that want to use a TTS engine have a
 couple new APIs for selecting an engine.</p>


 <h4>Using text-to-speech engines</h4>

 <p>In previous versions of Android, you could use the {@link android.speech.tts.TextToSpeech} class
 to perform text-to-speech (TTS) operations using the TTS engine provided by the system or set a
 custom engine using {@link android.speech.tts.TextToSpeech#setEngineByPackageName
 setEngineByPackageName()}. In Android 4.0, the {@link
 android.speech.tts.TextToSpeech#setEngineByPackageName setEngineByPackageName()} method has been
 deprecated and you can now specify the engine to use with a new {@link
 android.speech.tts.TextToSpeech} constructor that accepts the package name of a TTS engine.</p>

 <p>You can also query the available TTS engines with {@link
 android.speech.tts.TextToSpeech#getEngines()}. This method returns a list of {@link
 android.speech.tts.TextToSpeech.EngineInfo} objects, which include meta data such as the engine’s
 icon, label, and package name.</p>


 <h4>Building text-to-speech engines</h4>

 <p>Previously, custom engines required that the engine be built using an undocumented native header
 file. In Android 4.0, there is a complete set of framework APIs for building TTS engines. </p>

 <p>The basic setup requires an implementation of {@link android.speech.tts.TextToSpeechService} that
 responds to the {@link android.speech.tts.TextToSpeech.Engine#INTENT_ACTION_TTS_SERVICE} intent. The
 primary work for a TTS engine happens during the {@link
 android.speech.tts.TextToSpeechService#onSynthesizeText onSynthesizeText()} callback in a service
 that extends {@link android.speech.tts.TextToSpeechService}. The system delivers this method two
 objects:</p>
 <ul>
 <li>{@link android.speech.tts.SynthesisRequest}: This contains various data including the text to
 synthesize, the locale, the speech rate, and voice pitch.</li>
 <li>{@link android.speech.tts.SynthesisCallback}: This is the interface by which your TTS engine
 delivers the resulting speech data as streaming audio. First the engine must call {@link
 android.speech.tts.SynthesisCallback#start start()} to indicate that the engine is ready to deliver
 the audio, then call {@link android.speech.tts.SynthesisCallback#audioAvailable audioAvailable()},
 passing it the audio data in a byte buffer. Once your engine has passed all audio through the
 buffer, call {@link android.speech.tts.SynthesisCallback#done()}.</li>
 </ul>

 <p>Now that the framework supports a true API for creating TTS engines, support for the native code
 implementation has been removed. Look for a blog post about a compatibility layer
 that you can use to convert your old TTS engines to the new framework.</p>

 <p>For an example TTS engine using the new APIs, see the <a
 href="{@docRoot}resources/samples/TtsEngine/index.html">Text To Speech Engine</a> sample app.</p>


 <h3 id="SpellChecker">Spell Checker Services</h3>

 <p>A new spell checker framework allows apps to create spell checkers in a manner similar to the
 input method framework. To create a new spell checker, you must implement a service that extends
 {@link android.service.textservice.SpellCheckerService} and extend the {@link
 android.service.textservice.SpellCheckerService.Session} class to provide spelling suggestions based
 on text provided by interface callback methods. In the {@link
 android.service.textservice.SpellCheckerService.Session} callback methods, you must return the
 spelling suggestions as {@link android.view.textservice.SuggestionsInfo} objects. </p>

 <p>Applications with a spell checker service must declare the {@link
 android.Manifest.permission#BIND_TEXT_SERVICE} permission as required by the service, such that
 other services must have this permission in order for them to bind with the spell checker service.
 The service must also declare an intent filter with {@code &lt;action
 android:name="android.service.textservice.SpellCheckerService" />} as the intent’s action and should
 include a {@code &lt;meta-data&gt;} element that declares configuration information for the spell
 checker. </p>


 <h3 id="ActionBar">Action Bar</h3>

 <p>The {@link android.app.ActionBar} has been updated to support several new behaviors. Most
 importantly, the system gracefully manages the action bar’s size and configuration when running on
 smaller screens in order to provide an optimal user experience on all screen sizes. For example,
 when the screen is narrow (such as when a handset is in portrait orientation), the action bar’s
 navigation tabs appear in a “stacked bar," which appears directly below the main action bar. You can
 also opt-in to a “split action bar," which places all action items in a separate bar at the bottom
 of the screen when the screen is narrow.</p>


 <h4>Split action bar</h4>

 <p>If your action bar includes several action items, not all of them will fit into the action bar on
 a narrow screen, so the system will place more of them into the overflow menu. However, Android 4.0
 allows you to enable “split action bar" so that more action items can appear on the screen in a
 separate bar at the bottom of the screen. To enable split action bar, add {@link
 android.R.attr#uiOptions android:uiOptions} with {@code "splitActionBarWhenNarrow"} to either your
 <a href="guide/topics/manifest/application-element.html">{@code &lt;application&gt;}</a> tag or
 individual <a href="guide/topics/manifest/activity-element.html">{@code &lt;activity&gt;}</a> tags
 in your manifest file. When enabled, the system will add an additional bar at the bottom of the
 screen for all action items when the screen is narrow (no action items will appear in the primary
 action bar).</p>

 <p>If you want to use the navigation tabs provided by the {@link android.app.ActionBar.Tab} APIs,
 but don’t need the main action bar on top (you want only the tabs to appear at the top), then enable
 the split action bar as described above and also call {@link
 android.app.ActionBar#setDisplayShowHomeEnabled setDisplayShowHomeEnabled(false)} to disable the
 application icon in the action bar. With nothing left in the main action bar, it
 disappears&mdash;all that’s left are the navigation tabs at the top and the action items at the
 bottom of the screen.</p>


 <h4>Action bar styles</h4>

 <p>If you want to apply custom styling to the action bar, you can use new style properties {@link
 android.R.attr#backgroundStacked} and {@link android.R.attr#backgroundSplit} to apply a background
 drawable or color to the stacked bar and split bar, respectively. You can also set these styles at
 runtime with {@link android.app.ActionBar#setStackedBackgroundDrawable
 setStackedBackgroundDrawable()} and {@link android.app.ActionBar#setSplitBackgroundDrawable
 setSplitBackgroundDrawable()}.</p>


 <h4>Action provider</h4>

 <p>The new {@link android.view.ActionProvider} class allows you to create a specialized handler for
 action items. An action provider can define an action view, a default action behavior, and a submenu
 for each action item to which it is associated. When you want to create an action item that has
 dynamic behaviors (such as a variable action view, default action, or submenu), extending {@link
 android.view.ActionProvider} is a good solution in order to create a reusable component, rather than
 handling the various action item transformations in your fragment or activity.</p>

 <p>For example, the {@link android.widget.ShareActionProvider} is an extension of {@link
 android.view.ActionProvider} that facilitates a “share" action from the action bar. Instead of using
 traditional action item that invokes the {@link android.content.Intent#ACTION_SEND} intent, you can
 use this action provider to present an action view with a drop-down list of applications that handle
 the {@link android.content.Intent#ACTION_SEND} intent. When the user selects an application to use
 for the action, {@link android.widget.ShareActionProvider} remembers that selection and provides it
 in the action view for faster access to sharing with that app.</p>

 <p>To declare an action provider for an action item, include the {@code android:actionProviderClass}
 attribute in the <a href="{@docRoot}guide/topics/resources/menu-resource.html#item-element">{@code
 &lt;item&gt;}</a> element for your activity’s options menu, with the class name of the action
 provider as the value. For example:</p>

 <pre>
 &lt;item android:id="@+id/menu_share"
       android:title="Share"
       android:showAsAction="ifRoom"
       android:actionProviderClass="android.widget.ShareActionProvider" /&gt;
 </pre>

 <p>In your activity’s {@link android.app.Activity#onCreateOptionsMenu onCreateOptionsMenu()}
 callback method, retrieve an instance of the action provider from the menu item and set the
 intent:</p>

 <pre>
 public boolean onCreateOptionsMenu(Menu menu) {
     getMenuInflater().inflate(R.menu.options, menu);
     ShareActionProvider shareActionProvider =
           (ShareActionProvider) menu.findItem(R.id.menu_share).getActionProvider();
     // Set the share intent of the share action provider.
     shareActionProvider.setShareIntent(createShareIntent());
     ...
     return super.onCreateOptionsMenu(menu);
 }
 </pre>

 <p>For an example using the {@link android.widget.ShareActionProvider}, see the <a
 href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/app/
 ActionBarActionProviderActivity.html">ActionBarActionProviderActivity</a>
 class in ApiDemos.</p>


 <h4>Collapsible action views</h4>

 <p>Action items that provide an action view can now toggle between their action view state and
 traditional action item state. Previously only the {@link android.widget.SearchView} supported
 collapsing when used as an action view, but now you can add an action view for any action item and
 switch between the expanded state (action view is visible) and collapsed state (action item is
 visible).</p>

 <p>To declare that an action item that contains an action view be collapsible, include the {@code
 “collapseActionView"} flag in the {@code android:showAsAction} attribute for the <a
 href="{@docRoot}guide/topics/resources/menu-resource.html#item-element">{@code
 &lt;item&gt;}</a> element in the menu’s XML file.</p>

 <p>To receive callbacks when an action view switches between expanded and collapsed, register an
 instance of {@link android.view.MenuItem.OnActionExpandListener} with the respective {@link
 android.view.MenuItem} by calling {@link android.view.MenuItem#setOnActionExpandListener
 setOnActionExpandListener()}. Typically, you should do so during the {@link
 android.app.Activity#onCreateOptionsMenu onCreateOptionsMenu()} callback.</p>

 <p>To control a collapsible action view, you can call {@link
 android.view.MenuItem#collapseActionView()} and {@link android.view.MenuItem#expandActionView()} on
 the respective {@link android.view.MenuItem}.</p>

 <p>When creating a custom action view, you can also implement the new {@link
 android.view.CollapsibleActionView} interface to receive callbacks when the view is expanded and
 collapsed.</p>


 <h4>Other APIs for action bar</h4>
 <ul>
 <li>{@link android.app.ActionBar#setHomeButtonEnabled setHomeButtonEnabled()} allows you to specify
 whether the icon/logo behaves as a button to navigate home or “up" (pass “true" to make it behave as
 a button).</li>

 <li>{@link android.app.ActionBar#setIcon setIcon()} and {@link android.app.ActionBar#setLogo
 setLogo()} allow you to define the action bar icon or logo at runtime.</li>

 <li>{@link android.app.Fragment#setMenuVisibility Fragment.setMenuVisibility()} allows you to enable
 or disable the visibility of the options menu items declared by the fragment. This is useful if the
 fragment has been added to the activity, but is not visible, so the menu items should be
 hidden.</li>

 <li>{@link android.app.FragmentManager#invalidateOptionsMenu
 FragmentManager.invalidateOptionsMenu()}
 allows you to invalidate the activity options menu during various states of the fragment lifecycle
 in which using the equivalent method from {@link android.app.Activity} might not be available.</li>
 </ul>


 <h3 id="UI">User Interface and Views</h3>

 <p>Android 4.0 introduces a variety of new views and other UI components.</p>


 <h4>System UI</h4>

 <p>Since the early days of Android, the system has managed a UI component known as the <em>status
 bar</em>, which resides at the top of handset devices to deliver information such as the carrier
 signal, time, notifications, and so on. Android 3.0 added the <em>system bar</em> for tablet
 devices, which resides at the bottom of the screen to provide system navigation controls (Home,
 Back, and so forth) and also an interface for elements traditionally provided by the status bar.  In
 Android 4.0, the system provides a new type of system UI called the <em>navigation bar</em>. The
 navigation bar shares some qualities with the system bar, because it provides navigation controls
 for devices that don’t have hardware counterparts for navigating the system, but the navigation
 controls is all that the navigation bar offers (a device with the navigation bar, thus, also
 includes the status bar at the top of the screen).</p>

 <p>To this day, you can hide the status bar on handsets using the {@link
 android.view.WindowManager.LayoutParams#FLAG_FULLSCREEN} flag. In Android 4.0, the APIs that control
 the system bar’s visibility have been updated to better reflect the behavior of both the system bar
 and navigation bar:</p>
 <ul>
 <li>The {@link android.view.View#SYSTEM_UI_FLAG_LOW_PROFILE} flag replaces View.STATUS_BAR_HIDDEN
 flag. When set, this flag enables “low profile" mode for the system bar or
 navigation bar. Navigation buttons dim and other elements in the system bar also hide.</li>

 <li>The {@link android.view.View#SYSTEM_UI_FLAG_VISIBLE} flag replaces the {@code
 STATUS_BAR_VISIBLE} flag to request the system bar or navigation bar be visible.</li>

 <li>The {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION} is a new flag that requests that
 the navigation bar hide completely. Take note that this works only for the <em>navigation bar</em>
 used by some handsets (it does <strong>not</strong> hide the system bar on tablets). The navigation
 bar returns as soon as the system receives user input. As such, this mode is generally used for
 video playback or other cases in which the whole screen is needed but user input is not
 required.</li>
 </ul>

 <p>You can set each of these flags for the system bar and navigation bar by calling {@link
 android.view.View#setSystemUiVisibility setSystemUiVisibility()} on any view in your activity. The
 window manager will combine (OR-together) all flags from all views in your window and
 apply them to the system UI as long as your window has input focus. When your window loses input
 focus (the user navigates away from your app, or a dialog appears), your flags cease to have effect.
 Similarly, if you remove those views from the view hierarchy their flags no longer apply.</p>

 <p>To synchronize other events in your activity with visibility changes to the system UI (for
 example, hide the action bar or other UI controls when the system UI hides), you should register a
 {@link android.view.View.OnSystemUiVisibilityChangeListener} to be notified when the visibility
 of the system bar or navigation bar changes.</p>

 <p>See the <a
 href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/view/OverscanActivity.html">
 OverscanActivity</a> class for a demonstration of different system UI options.</p>


 <h4>GridLayout</h4>

 <p>{@link android.widget.GridLayout} is a new view group that places child views in a rectangular
 grid. Unlike {@link android.widget.TableLayout}, {@link android.widget.GridLayout} relies on a flat
 hierarchy and does not make use of intermediate views such as table rows for providing structure.
 Instead, children specify which row(s) and column(s) they should occupy (cells can span multiple
 rows and/or columns), and by default are laid out sequentially across the grid’s rows and columns.
 The {@link android.widget.GridLayout} orientation determines whether sequential children are by
 default laid out horizontally or vertically. Space between children may be specified either by using
 instances of the new {@link android.widget.Space} view or by setting the relevant margin parameters
 on children.</p>

 <p>See <a
 href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/view/index.html">ApiDemos</a
 >
 for samples using {@link android.widget.GridLayout}.</p>


 <h4>TextureView</h4>

 <p>{@link android.view.TextureView} is a new view that allows you to display a content stream, such
 as a video or an OpenGL scene. Although similar to {@link android.view.SurfaceView}, {@link
 android.view.TextureView} is unique in that it behaves like a regular view, rather than creating a
 separate window, so you can treat it like any other {@link android.view.View} object. For example,
 you can apply transforms, animate it using {@link android.view.ViewPropertyAnimator}, or
 adjust its opacity with {@link android.view.View#setAlpha setAlpha()}.</p>

 <p>Beware that {@link android.view.TextureView} works only within a hardware accelerated window.</p>

 <p>For more information, see the {@link android.view.TextureView} documentation.</p>


 <h4>Switch widget</h4>

 <p>The new {@link android.widget.Switch} widget is a two-state toggle that users can drag to one
 side or the other (or simply tap) to toggle an option between two states.</p>

 <p>You can use the {@code android:textOn} and {@code android:textOff} attributes to specify the text
 to appear on the switch when in the on and off setting. The {@code android:text} attribute also
 allows you to place a label alongside the switch.</p>

 <p>For a sample using switches, see the <a
 href="{@docRoot}resources/samples/ApiDemos/res/layout/switches.html">switches.xml</a> layout file
 and respective <a
 href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/view/Switches.html">Switches
 </a> activity.</p>


 <h4>Popup menus</h4>

 <p>Android 3.0 introduced {@link android.widget.PopupMenu} to create short contextual menus that pop
 up at an anchor point you specify (usually at the point of the item selected). Android 4.0 extends
 the {@link android.widget.PopupMenu} with a couple useful features:</p>
 <ul>
 <li>You can now easily inflate the contents of a popup menu from an XML <a
 href="{@docRoot}guide/topics/resources/menu-resource.html">menu resource</a> with {@link
 android.widget.PopupMenu#inflate inflate()}, passing it the menu resource ID.</li>
 <li>You can also now create a {@link android.widget.PopupMenu.OnDismissListener} that receives a
 callback when the menu is dismissed.</li>
 </ul>


 <h4>Preferences</h4>

 <p>A new {@link android.preference.TwoStatePreference} abstract class serves as the basis for
 preferences that provide a two-state selection option. The new {@link
 android.preference.SwitchPreference} is an extension of {@link
 android.preference.TwoStatePreference} that provides a {@link android.widget.Switch} widget in the
 preference view to allow users to toggle a setting on or off without the need to open an additional
 preference screen or dialog. For example, the Settings application uses a {@link
 android.preference.SwitchPreference} for the Wi-Fi and Bluetooth settings.</p>


 <h4>Hover events</h4>

 <p>The {@link android.view.View} class now supports “hover" events to enable richer interactions
 through the use of pointer devices (such as a mouse or other devices that drive an on-screen
 cursor).</p>

 <p>To receive hover events on a view, implement the {@link android.view.View.OnHoverListener} and
 register it with {@link android.view.View#setOnHoverListener setOnHoverListener()}. When a hover
 event occurs on the view, your listener receives a call to {@link
 android.view.View.OnHoverListener#onHover onHover()}, providing the {@link android.view.View} that
 received the event and a {@link android.view.MotionEvent} that describes the type of hover event
 that occurred. The hover event can be one of the following:</p>
 <ul>
 <li>{@link android.view.MotionEvent#ACTION_HOVER_ENTER}</li>
 <li>{@link android.view.MotionEvent#ACTION_HOVER_EXIT}</li>
 <li>{@link android.view.MotionEvent#ACTION_HOVER_MOVE}</li>
 </ul>

 <p>Your {@link android.view.View.OnHoverListener} should return true from {@link
 android.view.View.OnHoverListener#onHover onHover()} if it handles the hover event.  If your
 listener returns false, then the hover event will be dispatched to the parent view as usual.</p>

 <p>If your application uses buttons or other widgets that change their appearance based on the
 current state, you can now use the {@code android:state_hovered} attribute in a <a
 href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">state list drawable</a> to
 provide a different background drawable when a cursor hovers over the view.</p>

 <p>For a demonstration of the new hover events, see the <a
 href="{@docRoot}samples/ApiDemos/src/com/example/android/apis/view/Hover.html">Hover</a> class in
 ApiDemos.</p>


 <h4>Stylus and mouse button events</h4>

 <p>Android now provides APIs for receiving input from a stylus input device such as a digitizer
 tablet peripheral or a stylus-enabled touch screen.</p>

 <p>Stylus input operates in a similar manner to touch or mouse input.  When the stylus is in contact
 with the digitizer, applications receive touch events just like they would when a finger is used to
 touch the display.  When the stylus is hovering above the digitizer, applications receive hover
 events just like they would when a mouse pointer was being moved across the display when no buttons
 are pressed.</p>

 <p>Your application can distinguish between finger, mouse, stylus and eraser input by querying the
 “tool type" associated with each pointer in a {@link android.view.MotionEvent} using {@link
 android.view.MotionEvent#getToolType getToolType()}.  The currently defined tool types are: {@link
 android.view.MotionEvent#TOOL_TYPE_UNKNOWN}, {@link android.view.MotionEvent#TOOL_TYPE_FINGER},
 {@link android.view.MotionEvent#TOOL_TYPE_MOUSE}, {@link android.view.MotionEvent#TOOL_TYPE_STYLUS},
 and {@link android.view.MotionEvent#TOOL_TYPE_ERASER}.  By querying the tool type, your application
 can choose to handle stylus input in different ways from finger or mouse input.</p>

 <p>Your application can also query which mouse or stylus buttons are pressed by querying the “button
 state" of a {@link android.view.MotionEvent} using {@link android.view.MotionEvent#getButtonState
 getButtonState()}.  The currently defined button states are: {@link
 android.view.MotionEvent#BUTTON_PRIMARY}, {@link android.view.MotionEvent#BUTTON_SECONDARY}, {@link
 android.view.MotionEvent#BUTTON_TERTIARY}, {@link android.view.MotionEvent#BUTTON_BACK}, and {@link
 android.view.MotionEvent#BUTTON_FORWARD}. For convenience, the back and forward mouse buttons are
 automatically mapped to the {@link android.view.KeyEvent#KEYCODE_BACK} and {@link
 android.view.KeyEvent#KEYCODE_FORWARD} keys.  Your application can handle these keys to support
 mouse button based back and forward navigation.</p>

 <p>In addition to precisely measuring the position and pressure of a contact, some stylus input
 devices also report the distance between the stylus tip and the digitizer, the stylus tilt angle,
 and the stylus orientation angle.  Your application can query this information using {@link
 android.view.MotionEvent#getAxisValue getAxisValue()} with the axis codes {@link
 android.view.MotionEvent#AXIS_DISTANCE}, {@link android.view.MotionEvent#AXIS_TILT}, and {@link
 android.view.MotionEvent#AXIS_ORIENTATION}.</p>

 <p>For a demonstration of tool types, button states and the new axis codes, see the <a
 href="{@docRoot}samples/ApiDemos/src/com/example/android/apis/graphics/TouchPaint.html">TouchPaint
 </a> class in ApiDemos.</p>


 <h3 id="Properties">Properties</h3>

 <p>The new {@link android.util.Property} class provides a fast, efficient, and easy way to specify a
 property on any object that allows callers to generically set/get values on target objects. It also
 allows the functionality of passing around field/method references and allows code to set/get values
 of the property without knowing the details of what the fields/methods are.</p>

 <p>For example, if you want to set the value of field {@code bar} on object {@code foo}, you would
 previously do this:</p>
 <pre>
 foo.bar = value;
 </pre>

 <p>If you want to call the setter for an underlying private field {@code bar}, you would previously
 do this:</p>
 <pre>
 foo.setBar(value);
 </pre>

 <p>However, if you want to pass around the {@code foo} instance and have some other code set the
 {@code bar} value, there is really no way to do it prior to Android 4.0.</p>

 <p>Using the {@link android.util.Property} class, you can declare a {@link android.util.Property}
 object {@code BAR} on class {@code Foo} so that you can set the field on instance {@code foo} of
 class {@code Foo} like this:</p>
 <pre>
 BAR.set(foo, value);
 </pre>

 <p>The {@link android.view.View} class now leverages the {@link android.util.Property} class to
 allow you to set various fields, such as transform properties that were added in Android 3.0 ({@link
 android.view.View#ROTATION}, {@link android.view.View#ROTATION_X}, {@link
 android.view.View#TRANSLATION_X}, etc.).</p>

 <p>The {@link android.animation.ObjectAnimator} class also uses the {@link android.util.Property}
 class, so you can create an {@link android.animation.ObjectAnimator} with a {@link
 android.util.Property}, which is faster, more efficient, and more type-safe than the string-based
 approach.</p>


 <h3 id="HwAccel">Hardware Acceleration</h3>

 <p>Beginning with Android 4.0, hardware acceleration for all windows is enabled by default if your
 application has set either <a
 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code targetSdkVersion}</a> or
 <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code minSdkVersion}</a> to
 {@code “14"} or higher. Hardware acceleration generally results in smoother animations, smoother
 scrolling, and overall better performance and response to user interaction.</p>

 <p>If necessary, you can manually disable hardware acceleration with the <a
 href="{@docRoot}guide/topics/manifest/activity-element.html#hwaccel">{@code hardwareAccelerated}</a>
 attribute for individual <a href="{@docRoot}guide/topics/manifest/activity-element.html">{@code
 &lt;activity&gt;}</a> elements or the <a
 href="{@docRoot}guide/topics/manifest/application-element.html">{@code &lt;application&gt;}</a>
 element. You can alternatively disable hardware acceleration for individual views by calling {@link
 android.view.View#setLayerType setLayerType(LAYER_TYPE_SOFTWARE)}.</p>

 <p>For more information about hardware acceleration, including a list of unsupported drawing
 operations, see the <a href="{@docRoot}guide/topics/graphics/hardware-accel.html">Hardware
 Acceleration</a> document.</p>


 <h3 id="Jni">JNI Changes</h3>

 <p>In previous versions of Android, JNI local references weren’t indirect handles; Android used
 direct pointers. This wasn't a problem as long as the garbage collector didn't move objects, but it
 seemed to work because it made it possible to write buggy code. In Android 4.0, the system now uses
 indirect references in order to detect these bugs.</p>

 <p>The ins and outs of JNI local references are described in “Local and Global References" in <a
 href="{@docRoot}guide/practices/design/jni.html">JNI Tips</a>. In Android 4.0, <a
 href="http://android-developers.blogspot.com/2011/07/debugging-android-jni-with-checkjni.html">
 CheckJNI</a> has been enhanced to detect these errors. Watch the <a
 href="http://android-developers.blogspot.com/">Android Developers Blog</a> for an upcoming post
 about common errors with JNI references and how you can fix them.</p>

 <p>This change in the JNI implementation only affects apps that target Android 4.0 by setting either
 the <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code
 targetSdkVersion}</a> or <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code
 minSdkVersion}</a> to {@code “14"} or higher. If you’ve set these attributes to any lower value,
 then JNI local references behave the same as in previous versions.</p>


 <h3 id="WebKit">WebKit</h3>
 <ul>
 <li>WebKit updated to version 534.30</li>
 <li>Support for Indic fonts (Devanagari, Bengali, and Tamil, including the complex character support
 needed for combining glyphs) in {@link android.webkit.WebView} and the built-in Browser</li>
 <li>Support for Ethiopic, Georgian, and Armenian fonts in {@link android.webkit.WebView} and the
 built-in Browser</li>
 <li>Support for <a
 href="http://google-opensource.blogspot.com/2009/05/introducing-webdriver.html">WebDriver</a> makes
 it easier for you to test apps that use {@link android.webkit.WebView}</li>
 </ul>


 <h4>Android Browser</h4>

 <p>The Browser application adds the following features to support web applications:</p>
 <ul>
 <li>Updated V8 JavaScript compiler for faster performance</li>
 <li>Plus other notable enhancements carried over from <a
 href="{@docRoot}sdk/android-3.0.html">Android
 3.0</a> are now available for handsets:
 <ul>
 <li>Support for fixed position elements on all pages</li>
 <li><a href="http://dev.w3.org/2009/dap/camera/">HTML media capture</a></li>
 <li><a href="http://dev.w3.org/geo/api/spec-source-orientation.html">Device orientation
 events</a></li>
 <li><a href="http://www.w3.org/TR/css3-3d-transforms/">CSS 3D transformations</a></li>
 </ul>
 </li>
 </ul>


 <h3 id="Permissions">Permissions</h3>

 <p>The following are new permissions:</p>
 <ul>
 <li>{@link android.Manifest.permission#ADD_VOICEMAIL}: Allows a voicemail service to add voicemail
 messages to the device.</li>
 <li>{@link android.Manifest.permission#BIND_TEXT_SERVICE}: A service that implements {@link
 android.service.textservice.SpellCheckerService} must require this permission for itself.</li>
 <li>{@link android.Manifest.permission#BIND_VPN_SERVICE}: A service that implements {@link
 android.net.VpnService} must require this permission for itself.</li>
 <li>{@link android.Manifest.permission#READ_PROFILE}: Provides read access to the {@link
 android.provider.ContactsContract.Profile} provider.</li>
 <li>{@link android.Manifest.permission#WRITE_PROFILE}: Provides write access to the {@link
 android.provider.ContactsContract.Profile} provider.</li>
 </ul>


 <h3 id="DeviceFeatures">Device Features</h3>

 <p>The following are new device features:</p>
 <ul>
 <li>{@link android.content.pm.PackageManager#FEATURE_WIFI_DIRECT}: Declares that the application
 uses
 Wi-Fi for peer-to-peer communications.</li>
 </ul>


 <h2 id="Honeycomb">Previous APIs</h2>

 <p>In addition to everything above, Android 4.0 naturally supports all APIs from previous releases.
 Because the Android 3.x (Honeycomb) platform is available only for large-screen devices, if you've
 been developing primarily for handsets, then you might not be aware of all the APIs added to Android
 in these recent releases.</p>

 <p>Here's a look at some of the most notable APIs you might have missed that are now available
 on handsets as well:</p>

 <dl>
   <dt><a href="android-3.0.html">Android 3.0</a></dt>
   <dd>
     <ul>
       <li>{@link android.app.Fragment}: A framework component that allows you to separate distinct
 elements of an activity into self-contained modules that define their own UI and lifecycle. See the
 <a href="{@docRoot}guide/topics/fundamentals/fragments.html">Fragments</a> developer guide.</li>
       <li>{@link android.app.ActionBar}: A replacement for the traditional title bar at the top of
 the activity window. It includes the application logo in the left corner and provides a new
 interface for menu items. See the
 <a href="{@docRoot}guide/topics/ui/actionbar.html">Action Bar</a> developer guide.</li>
       <li>{@link android.content.Loader}: A framework component that facilitates asynchronour
 loading of data in combination with UI components to dynamically load data without blocking the
 main thread. See the
 <a href="{@docRoot}guide/topics/fundamentals/loaders.html">Loaders</a> developer guide.</li>
       <li>System clipboard: Applications can copy and paste data (beyond mere text) to and from
 the system-wide clipboard. Clipped data can be plain text, a URI, or an intent. See the
 <a href="{@docRoot}guide/topics/clipboard/copy-paste.html">Copy and Paste</a> developer guide.</li>
       <li>Drag and drop: A set of APIs built into the view framework that facilitates drag and drop
 operations. See the
 <a href="{@docRoot}guide/topics/ui/drag-drop.html">Drag and Drop</a> developer guide.</li>
       <li>An all new flexible animation framework allows you to animate arbitrary properties of any
 object (View, Drawable, Fragment, Object, or anything else) and define animation aspects such
 as duration, interpolation, repeat and more. The new framework makes Animations in Android
 simpler than ever. See the
 <a href="{@docRoot}guide/topics/graphics/property-animation.html">Property Animation</a> developer
 guide.</li>
       <li>RenderScript graphics and compute engine: RenderScript offers a high performance 3D
 graphics rendering and compute API at the native level, which you write in the C (C99 standard),
 providing the type of performance you expect from a native environment while remaining portable
 across various CPUs and GPUs. See the
 <a href="{@docRoot}guide/topics/renderscript/index.html">RenderScript</a> developer
 guide.</li>
       <li>Hardware accelerated 2D graphics: You can now enable the OpenGL renderer for your
 application by setting {android:hardwareAccelerated="true"} in your manifest element's <a
 href="{@docRoot}guide/topics/manifest/application-element.html"><code>&lt;application&gt;</code></a>
 element or for individual <a
 href="{@docRoot}guide/topics/manifest/activity-element.html"><code>&lt;activity&gt;</code></a>
 elements. This results
 in smoother animations, smoother scrolling, and overall better performance and response to user
 interaction.
       <p class="note"><strong>Note:</strong> If you set your application's <a
 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code minSdkVersion}</a> or <a
 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code targetSdkVersion}</a> to
 {@code "14"} or higher, hardware acceleration is enabled by default.</p></li>
       <li>And much, much more. See the <a href="android-3.0.html">Android 3.0 Platform</a>
 notes for more information.</li>
     </ul>
   </dd>

   <dt><a href="android-3.1.html">Android 3.1</a></dt>
   <dd>
     <ul>
       <li>USB APIs: Powerful new APIs for integrating connected peripherals with
 Android applications. The APIs are based on a USB stack and services that are
 built into the platform, including support for both USB host and device interactions. See the <a
 href="{@docRoot}guide/topics/usb/index.html">USB Host and Accessory</a> developer guide.</li>
       <li>MTP/PTP APIs: Applications can interact directly with connected cameras and other PTP
 devices to receive notifications when devices are attached and removed, manage files and storage on
 those devices, and transfer files and metadata to and from them. The MTP API implements the PTP
 (Picture Transfer Protocol) subset of the MTP (Media Transfer Protocol) specification. See the
 {@link android.mtp} documentation.</li>
       <li>RTP APIs: Android exposes an API to its built-in RTP (Real-time Transport Protocol) stack,
 which applications can use to manage on-demand or interactive data streaming. In particular, apps
 that provide VOIP, push-to-talk, conferencing, and audio streaming can use the API to initiate
 sessions and transmit or receive data streams over any available network. See the {@link
 android.net.rtp} documentation.</li>
       <li>Support for joysticks and other generic motion inputs.</li>
       <li>See the <a href="android-3.1.html">Android 3.1 Platform</a>
 notes for many more new APIs.</li>
     </ul>
   </dd>

   <dt><a href="android-3.2.html">Android 3.2</a></dt>
   <dd>
     <ul>
       <li>New screens support APIs that give you more control over how your applications are
 displayed across different screen sizes. The API extends the existing screen support model with the
 ability to precisely target specific screen size ranges by dimensions, measured in
 density-independent pixel units (such as 600dp or 720dp wide), rather than by their generalized
 screen sizes (such as large or xlarge). For example, this is important in order to help you
 distinguish between a 5" device and a 7" device, which would both traditionally be bucketed as
 "large" screens. See the blog post, <a
 href="http://android-developers.blogspot.com/2011/07/new-tools-for-managing-screen-sizes.html">
 New Tools for Managing Screen Sizes</a>.</li>
       <li>New constants for <a
 href="{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code &lt;uses-feature&gt;}</a> to
 declare landscape or portrait screen orientation requirements.</li>
       <li>The device "screen size" configuration now changes during a screen orientation
 change. If your app targets API level 13 or higher, you must handle the {@code "screenSize"}
 configuration change if you also want to handle the {@code "orientation"} configuration change. See
 <a href="{@docRoot}guide/topics/manifest/activity-element.html#config">{@code
 android:configChanges}</a> for more information.</li>
       <li>See the <a href="android-3.2.html">Android 3.2 Platform</a>
 notes for other new APIs.</li>
     </ul>
   </dd>

 </dl>


 <h2 id="api-diff">API Differences Report</h2>

 <p>For a detailed view of all API changes in Android {@sdkPlatformVersion} (API Level
 {@sdkPlatformApiLevel}), see the <a
 href="{@docRoot}sdk/api_diff/{@sdkPlatformApiLevel}/changes.html">API Differences Report</a>.</p>


 <h2 id="api-level">API Level</h2>

 <p>The Android {@sdkPlatformVersion} API is assigned an integer
 identifier&mdash;<strong>{@sdkPlatformApiLevel}</strong>&mdash;that is stored in the system itself.
 This identifier, called the "API level", allows the system to correctly determine whether an
 application is compatible with the system, prior to installing the application. </p>

 <p>To use APIs introduced in Android {@sdkPlatformVersion} in your application, you need compile the
 application against an Android platform that supports API level {@sdkPlatformApiLevel} or
 higher. Depending on your needs, you might also need to add an
 <code>android:minSdkVersion="{@sdkPlatformApiLevel}"</code> attribute to the
 <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">{@code &lt;uses-sdk&gt;}</a>
 element.</p>

 <p>For more information, see the <a href="{@docRoot}guide/appendix/api-levels.html">API Levels</a>
 document. </p>


 <h2 id="apps">Built-in Applications</h2>

 <p>The system image included in the downloadable platform provides these
 built-in applications:</p>

 <table style="border:0;padding-bottom:0;margin-bottom:0;">
 <tr>
 <td style="border:0;padding-bottom:0;margin-bottom:0;">
 <ul>
 <li>API Demos</li>
 <li>Browser</li>
 <li>Calculator</li>
 <li>Calendar</li>
 <li>Camera</li>
 <li>Clock</li>
 <li>Custom Locale</li>
 <li>Dev Tools</li>
 <li>Downloads</li>
 <li>Email</li>
 <li>Gallery</li>
 </ul>
 </td>
 <td style="border:0;padding-bottom:0;margin-bottom:0;padding-left:5em;">
 <ul>
 <li>Gestures Builder</li>
 <li>Messaging</li>
 <li>Music</li>
 <li>People</li>
 <li>Phone</li>
 <li>Search</li>
 <li>Settings</li>
 <li>Speech Recorder</li>
 <li>Speech Recorder</li>
 <li>Widget Preview</li>
 </ul>
 </td>
 </tr>
 </table>


 <h2 id="locs" style="margin-top:.75em;">Locales</h2>

 <p>The system image included in the downloadable SDK platform provides a variety of built-in
 locales. In some cases, region-specific strings are available for the locales. In other cases, a
 default version of the language is used. The languages that are available in the Android 3.0 system
 image are listed below (with <em>language</em>_<em>country/region</em> locale descriptor).</p>

 <table style="border:0;padding-bottom:0;margin-bottom:0;">
 <tr>
 <td style="border:0;padding-bottom:0;margin-bottom:0;">
 <ul>
 <li>Arabic, Egypt (ar_EG)</li>
 <li>Arabic, Israel (ar_IL)</li>
 <li>Bulgarian, Bulgaria (bg_BG)</li>
 <li>Catalan, Spain (ca_ES)</li>
 <li>Czech, Czech Republic (cs_CZ)</li>
 <li>Danish, Denmark(da_DK)</li>
 <li>German, Austria (de_AT)</li>
 <li>German, Switzerland (de_CH)</li>
 <li>German, Germany (de_DE)</li>
 <li>German, Liechtenstein (de_LI)</li>
 <li>Greek, Greece (el_GR)</li>
 <li>English, Australia (en_AU)</li>
 <li>English, Canada (en_CA)</li>
 <li>English, Britain (en_GB)</li>
 <li>English, Ireland (en_IE)</li>
 <li>English, India (en_IN)</li>
 <li>English, New Zealand (en_NZ)</li>
 <li>English, Singapore(en_SG)</li>
 <li>English, US (en_US)</li>
 <li>English, Zimbabwe (en_ZA)</li>
 <li>Spanish (es_ES)</li>
 <li>Spanish, US (es_US)</li>
 <li>Finnish, Finland (fi_FI)</li>
 <li>French, Belgium (fr_BE)</li>
 <li>French, Canada (fr_CA)</li>
 <li>French, Switzerland (fr_CH)</li>
 <li>French, France (fr_FR)</li>
 <li>Hebrew, Israel (he_IL)</li>
 <li>Hindi, India (hi_IN)</li>
 </ul>
 </td>
 <td style="border:0;padding-bottom:0;margin-bottom:0;padding-left:5em;">
 <li>Croatian, Croatia (hr_HR)</li>
 <li>Hungarian, Hungary (hu_HU)</li>
 <li>Indonesian, Indonesia (id_ID)</li>
 <li>Italian, Switzerland (it_CH)</li>
 <li>Italian, Italy (it_IT)</li>
 <li>Japanese (ja_JP)</li>
 <li>Korean (ko_KR)</li>
 <li>Lithuanian, Lithuania (lt_LT)</li>
 <li>Latvian, Latvia (lv_LV)</li>
 <li>Norwegian bokmål, Norway (nb_NO)</li>
 <li>Dutch, Belgium (nl_BE)</li>
 <li>Dutch, Netherlands (nl_NL)</li>
 <li>Polish (pl_PL)</li>
 <li>Portuguese, Brazil (pt_BR)</li>
 <li>Portuguese, Portugal (pt_PT)</li>
 <li>Romanian, Romania (ro_RO)</li>
 <li>Russian (ru_RU)</li></li>
 <li>Slovak, Slovakia (sk_SK)</li>
 <li>Slovenian, Slovenia (sl_SI)</li>
 <li>Serbian (sr_RS)</li>
 <li>Swedish, Sweden (sv_SE)</li>
 <li>Thai, Thailand (th_TH)</li>
 <li>Tagalog, Philippines (tl_PH)</li>
 <li>Turkish, Turkey (tr_TR)</li>
 <li>Ukrainian, Ukraine (uk_UA)</li>
 <li>Vietnamese, Vietnam (vi_VN)</li>
 <li>Chinese, PRC (zh_CN)</li>
 <li>Chinese, Taiwan (zh_TW)</li>
 </td>
 </tr>
 </table>

 <p class="note"><strong>Note:</strong> The Android platform may support more
 locales than are included in the SDK system image. All of the supported locales
 are available in the <a href="http://source.android.com/">Android Open Source
 Project</a>.</p>

 <h2 id="skins">Emulator Skins</h2>

 <p>The downloadable platform includes the following emulator skins:</p>

 <ul>
   <li>
     QVGA (240x320, low density, small screen)
   </li>
   <li>
     WQVGA400 (240x400, low density, normal screen)
   </li>
   <li>
     WQVGA432 (240x432, low density, normal screen)
   </li>
   <li>
     HVGA (320x480, medium density, normal screen)
   </li>
   <li>
     WVGA800 (480x800, high density, normal screen)
   </li>
   <li>
     WVGA854 (480x854 high density, normal screen)
   </li>
   <li>
     WXGA720 (1280x720, extra-high density, normal screen) <span class="new">new</span>
   </li>
   <li>
     WSVGA (1024x600, medium density, large screen) <span class="new">new</span>
   </li>
   <li>
     WXGA (1280x800, medium density, xlarge screen)
   </li>
 </ul>

 <p>To test your application on an emulator that represents the latest Android device, you can create
 an AVD with the new WXGA720 skin (it's an xhdpi, normal screen device). Note that the emulator
 currently doesn't support the new on-screen navigation bar for devices without hardware navigation
 buttons, so when using this skin, you must use keyboard keys <em>Home</em> for the Home button,
 <em>ESC</em> for the Back button, and <em>F2</em> or <em>Page-up</em> for the Menu button.</p>

 <p>However, due to performance issues in the emulator when running high-resolution screens such as
 the one for the WXGA720 skin, we recommend that you primarily use the traditional WVGA800 skin
 (hdpi, normal screen) to test your application.</p>