docs/html/preview/api-overview.jd

page.title=API Overview
page.keywords=preview,sdk,compatibility
page.tags=previewresources, androidm
sdk.platform.apiLevel=22-mnc
page.image=images/cards/card-api-overview_16-9_2x.png
@jd:body


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

<h2>In this document
    <a href="#" onclick="hideNestedItems('#toc44',this);return false;" class="header-toggle">
        <span class="more">show more</span>
        <span class="less" style="display:none">show less</span></a></h2>

<ol id="toc44" class="hide-nested">
  <li><a href="#app-linking">App Linking</a></li>
  <li><a href="#backup">Auto Backup for Apps</a></li>
  <li><a href="#authentication">Authentication</a>
    <ol>
      <li><a href="#fingerprint-authentication">Fingerprint Authentication</a></li>
      <li><a href="#confirm-credential">Confirm Credential</a></li>
    </ol>
  </li>
  <li><a href="#direct-share">Direct Share</a></li>
  <li><a href="#voice-interactions">Voice Interactions</a></li>
  <li><a href="#assist">Assist API</a></li>
  <li><a href="#notifications">Notifications</a></li>
  <li><a href="#bluetooth-stylus">Bluetooth Stylus Support</a></li>
  <li><a href="#ble-scanning">Improved Bluetooth Low Energy Scanning</a></li>
  <li><a href="#hotspot">Hotspot 2.0 Release 1 Support</a></li>
  <li><a href="#4K-display">4K Display Mode</a></li>
  <li><a href="#behavior-themeable-colorstatelists">Themeable ColorStateLists</a></li>
  <li><a href="#audio">Audio Features</a></li>
  <li><a href="#video">Video Features</a></li>
  <li><a href="#camera">Camera Features</a>
    <ol>
      <li><a href="#flashlight">Flashlight API</a></li>
      <li><a href="#reprocessing">Camera Reprocessing</a></li>
    </ol>
  </li>
  <li><a href="#afw">Android for Work Features</a></li>
</ol>

<h2>API Differences</h2>
<ol>
<li><a href="{@docRoot}preview/download.html">API level 22 to M Preview &raquo;</a> </li>
</ol>

</div>
</div>

<p>The M Developer Preview gives you an advance look at the upcoming release
for the Android platform, which offers new features for users and app
developers. This document provides an introduction to the most notable APIs.</p>

<p>The M Developer Preview is intended for <strong>developer early
adopters</strong> and <strong>testers</strong>. If you are interested in
influencing the direction of the Android framework,
<a href="{@docRoot}preview/setup-sdk.html">give the M Developer Preview a
try</a> and send us your feedback!</p>

<p class="caution"><strong>Caution:</strong> Do not publish apps
that use the M Developer Preview to the Google Play store.</p>

<p class="note"><strong>Note:</strong> This document often refers to classes and
methods that do not yet have reference material available on <a
href="{@docRoot}">developer.android.com</a>. These API elements are
formatted in {@code code style} in this document (without hyperlinks). For the
preliminary API documentation for these elements, download the <a
href="{@docRoot}preview/download.html#docs"> preview reference</a>.</p>

<h3>Important behavior changes</h3>

<p>If you have previously published an app for Android, be aware that your app might be affected
by changes in the platform.</p>

<p>Please see <a href="behavior-changes.html">Behavior Changes</a> for complete information.</p>

<h2 id="app-linking">App Linking</h2>
<p>This preview enhances Android’s intent system by providing more powerful app linking.
This feature allows you to associate an app with a web domain you own. Based on this
association, the platform can determine the default app to use to handle a particular
web link and skip prompting users to select an app. To learn how to implement this feature, see
<a href="{@docRoot}preview/features/app-linking.html">App Linking</a>.

<h2 id="backup">Auto Backup for Apps</h2>
<p>The system now performs automatic full data backup and restore for apps. For the
duration of the <a href="{@docRoot}preview/overview.html">M Developer Preview program</a>, all
apps are backed up, independent of which SDK version they target. After the final M SDK release,
your app must target M to enable this behavior; you do not need to add any additional code. If users
delete their Google accounts, their backup data is deleted as well. To learn how this feature
works and how to configure what to back up on the file system, see
<a href="{@docRoot}preview/backup/index.html">Auto Backup for Apps</a>.</p>

<h2 id="authentication">Authentication</h2>
<p>This preview offers new APIs to let you authenticate users by using their fingerprint scans on
supported devices, and check how recently the user was last authenticated using a device unlocking
mechanism (such as a lockscreen password). Use these APIs in conjunction with
the <a href="{@docRoot}training/articles/keystore.html">Android Keystore system</a>.</p>

<h3 id="fingerprint-authentication">Fingerprint Authentication</h3>

<p>To authenticate users via fingerprint scan, get an instance of the new
{@link android.hardware.fingerprint.FingerprintManager} class and call the
{@link android.hardware.fingerprint.FingerprintManager#authenticate(android.hardware.fingerprint.FingerprintManager.CryptoObject, android.os.CancellationSignal, int, android.hardware.fingerprint.FingerprintManager.AuthenticationCallback, android.os.Handler) authenticate()}
method. Your app must be running on a compatible
device with a fingerprint sensor. You must implement the user interface for the fingerprint
authentication flow on your app, and use the standard Android fingerprint icon in your UI.
The Android fingerprint icon ({@code c_fp_40px.png}) is included in the
<a href="https://github.com/googlesamples/android-FingerprintDialog"
class="external-link">sample app</a>. If you are developing multiple apps that use fingerprint
authentication, note that each app must authenticate the user’s fingerprint independently.
</p>

<p>To use this feature in your app, first add the
  {@link android.Manifest.permission#USE_FINGERPRINT} permission in your manifest.</p>

<pre>
&lt;uses-permission
        android:name="android.permission.USE_FINGERPRINT" /&gt;
</pre>
<img src="{@docRoot}preview/images/fingerprint-screen.png"
srcset="{@docRoot}preview/images/fingerprint-screen.png 1x, {@docRoot}preview/images/fingerprint-screen_2x.png 2x"
style="float:right; margin:0 0 10px 20px" width="282" height="476" />

<p>To see an app implementation of fingerprint authentication, refer to the
<a href="https://github.com/googlesamples/android-FingerprintDialog" class="external-link">
  Fingerprint Dialog sample</a>. For a demonstration of how you can use these authentication
  APIs in conjunction with other Android APIs, see the video
  <a class="video-shadowbox-button" href="https://www.youtube.com/watch?v=VOn7VrTRlA4">
  Fingerprint and Payment APIs</a>.</p>

<p>If you are testing this feature, follow these steps:</p>
<ol>
<li>Install Android SDK Tools Revision 24.3, if you have not done so.</li>
<li>Enroll a new fingerprint in the emulator by going to
<strong>Settings > Security > Fingerprint</strong>, then follow the enrollment instructions.</li>
<li>Use an emulator to emulate fingerprint touch events with the
following command. Use the same command to emulate fingerprint touch events on the lockscreen or
in your app.
<pre class="no-prettyprint">
adb -e emu finger touch &lt;finger_id&gt;
</pre>
<p>On Windows, you may have to run {@code telnet 127.0.0.1 &lt;emulator-id&gt;} followed by
  {@code finger touch &lt;finger_id&gt;}.
</p>
</li>
</ol>

<h3 id="confirm-credential">Confirm Credential</h3>
<p>Your app can authenticate users based on how recently they last unlocked their device. This
feature frees users from having to remember additional app-specific passwords, and avoids the need
for you to implement your own authentication user interface. Your app should use this feature in
conjunction with a public or secret key implementation for user authentication.</p>

<p>To set the timeout duration for which the same key can be re-used after a user is successfully
authenticated, call the new
{@link android.security.keystore.KeyGenParameterSpec.Builder#setUserAuthenticationValidityDurationSeconds(int) setUserAuthenticationValidityDurationSeconds()}
method when you set up a {@link javax.crypto.KeyGenerator} or
{@link java.security.KeyPairGenerator}.</p>

<p>Avoid showing the re-authentication dialog excessively -- your apps should try using the
cryptographic object first and if the the timeout expires, use the
{@link android.app.KeyguardManager#createConfirmDeviceCredentialIntent(java.lang.CharSequence, java.lang.CharSequence) createConfirmDeviceCredentialIntent()}
method to re-authenticate the user within your app.
</p>

<p>To see an app implementation of this feature, refer to the
<a href="https://github.com/googlesamples/android-ConfirmCredential" class="external-link">
  Confirm Credential sample</a>.</p>

<h2 id="direct-share">Direct Share</h2>

<img src="{@docRoot}preview/images/direct-share-screen.png"
srcset="{@docRoot}preview/images/direct-share-screen.png 1x, {@docRoot}preview/images/direct-share-screen_2x.png 2x"
style="float:right; margin:0 0 20px 30px" width="312" height="329" />

<p>This preview provides you with APIs to make sharing intuitive and quick for users. You can now
define <em>direct share targets</em> that launch a specific activity in your app. These direct share
targets are exposed to users via the <em>Share</em> menu. This feature allows users to share
content to targets, such as contacts, within other apps. For example, the direct share target might
launch an activity in another social network app, which lets the user share content directly to a
specific friend or community in that app.</p>

<p>To enable direct share targets you must define a class that extends the
{@link android.service.chooser.ChooserTargetService} class. Declare your
service in the manifest. Within that declaration, specify the
{@link android.Manifest.permission#BIND_CHOOSER_TARGET_SERVICE} permission and an
intent filter using the
{@link android.service.chooser.ChooserTargetService#SERVICE_INTERFACE SERVICE_INTERFACE} action.</p>
<p>The following example shows how you might declare the
{@link android.service.chooser.ChooserTargetService} in your manifest.</p>
<pre>
&lt;service android:name=".ChooserTargetService"
        android:label="&#64;string/service_name"
        android:permission="android.permission.BIND_CHOOSER_TARGET_SERVICE"&gt;
    &lt;intent-filter&gt;
        &lt;action android:name="android.service.chooser.ChooserTargetService" /&gt;
    &lt;/intent-filter&gt;
&lt;/service&gt;
</pre>

<p>For each activity that you want to expose to
{@link android.service.chooser.ChooserTargetService}, add a
{@code &lt;meta-data&gt;} element with the name
{@code "android.service.chooser.chooser_target_service"} in your app manifest.
</p>

<pre>
&lt;activity android:name=".MyShareActivity”
        android:label="&#64;string/share_activity_label"&gt;
    &lt;intent-filter>
        &lt;action android:name="android.intent.action.SEND" /&gt;
    &lt;/intent-filter>
&lt;meta-data
        android:name="android.service.chooser.chooser_target_service"
        android:value=".ChooserTargetService" /&gt;
&lt;/activity>
</pre>

<h2 id="voice-interactions">Voice Interactions</h2>
<p>
This preview provides a new voice interaction API which, together with
<a href="https://developers.google.com/voice-actions/" class="external-link">Voice Actions</a>,
allows you to build conversational voice experiences into your apps. Call the
{@link android.app.Activity#isVoiceInteraction()} method to determine if a voice action triggered
your activity. If so, your app can use the
{@link android.app.VoiceInteractor} class to request a voice confirmation from the user, select
from a list of options, and more.</p>

<p>Most voice interactions originate from a user voice action. A voice interaction activity can
also, however, start without user input. For example, another app launched through a voice
interaction can also send an intent to launch a voice interaction. To determine if your activity
launched from a user voice query or from another voice interaction app, call the
{@link android.app.Activity#isVoiceInteractionRoot()} method. If another app launched your
activity, the method returns {@code false}. Your app may then prompt the user to confirm that
they intended this action.</p>

<p>To learn more about implementing voice actions, see the
<a href="https://developers.google.com/voice-actions/interaction/"
class="external-link">Voice Actions developer site</a>.
</p>

<h2 id="assist">Assist API</h2>
<p>
This preview offers a new way for users to engage with your apps through an assistant. To use this
feature, the user must enable the assistant to use the current context. Once enabled, the user
can summon the assistant within any app, by long-pressing on the <strong>Home</strong> button.</p>
<p>Your app can elect to not share the current context with the assistant by setting the
{@link android.view.WindowManager.LayoutParams#FLAG_SECURE} flag. In addition to the
standard set of information that the platform passes to the assistant, your app can share
additional information by using the new {@link android.app.assist.AssistContent} class.</p>

<p>To provide the assistant with additional context from your app, follow these steps:</p>

<ol>
<li>Implement the {@link android.app.Application.OnProvideAssistDataListener} interface.</li>
<li>Register this listener by using
{@link android.app.Application#registerOnProvideAssistDataListener(android.app.Application.OnProvideAssistDataListener) registerOnProvideAssistDataListener()}.</li>
<li>In order to provide activity-specific contextual information, override the
{@link android.app.Activity#onProvideAssistData(android.os.Bundle) onProvideAssistData()}
callback and, optionally, the new
{@link android.app.Activity#onProvideAssistContent(android.app.assist.AssistContent) onProvideAssistContent()}
callback.
</ol>

<h2 id="notifications">Notifications</h2>
<p>This preview adds the following API changes for notifications:</p>
<ul>
  <li>New {@link android.app.NotificationManager#INTERRUPTION_FILTER_ALARMS} filter level that
    corresponds to the new <em>Alarms only</em> do not disturb mode.</li>
  <li>New {@link android.app.Notification#CATEGORY_REMINDER} category value that is used to
  distinguish user-scheduled reminders from other events
  ({@link android.app.Notification#CATEGORY_EVENT}) and alarms
  ({@link android.app.Notification#CATEGORY_ALARM}).</li>
  <li>New {@link android.graphics.drawable.Icon} class that you can attach to your notifications
  via the
  {@link android.app.Notification.Builder#setSmallIcon(android.graphics.drawable.Icon) setSmallIcon()}
  and {@link android.app.Notification.Builder#setLargeIcon(android.graphics.drawable.Icon) setLargeIcon()}
  methods. Similarly, the
  {@link android.app.Notification.Builder#addAction(int, java.lang.CharSequence, android.app.PendingIntent)
  addAction()} method now accepts an {@link android.graphics.drawable.Icon} object instead of a
  drawable resource ID.</li>
  <li>New {@link android.app.NotificationManager#getActiveNotifications()} method that allows your
  apps to find out which of their notifications are currently alive. To see an app implementation
  that uses this feature, see the <a href="https://github.com/googlesamples/android-ActiveNotifications"
  class="external-link">Active Notifications sample</a>.</li>
</ul>

<h2 id="bluetooth-stylus">Bluetooth Stylus Support</h2>
<p>This preview provides improved support for user input using a Bluetooth stylus. Users can pair
and connect a compatible Bluetooth stylus with their phone or tablet.  While connected, position
information from the touch screen is fused with pressure and button information from the stylus to
provide a greater range of expression than with the touch screen alone. Your app can listen for
stylus button presses and perform secondary actions, by registering
{@link android.view.View.OnContextClickListener} and
{@link android.view.GestureDetector.OnContextClickListener} objects in your activity.</p>

<p>Use the {@link android.view.MotionEvent} methods and constants to detect stylus button
interactions:</p>
<ul>
<li>If the user touches a stylus with a button on the screen of your app, the
{@link android.view.MotionEvent#getToolType(int) getTooltype()} method returns
{@link android.view.MotionEvent#TOOL_TYPE_STYLUS}.</li>
<li>For apps targeting M Preview, the
{@link android.view.MotionEvent#getButtonState() getButtonState()}
method returns {@link android.view.MotionEvent#BUTTON_STYLUS_PRIMARY} when the user
presses the primary stylus button. If the stylus has a second button, the same method returns
{@link android.view.MotionEvent#BUTTON_STYLUS_SECONDARY} when the user presses it. If the user presses
both buttons simultaneously, the method returns both values OR'ed together
({@link android.view.MotionEvent#BUTTON_STYLUS_PRIMARY}|{@link android.view.MotionEvent#BUTTON_STYLUS_SECONDARY}).</li>
<li>
For apps targeting a lower platform version, the
{@link android.view.MotionEvent#getButtonState() getButtonState()} method returns
{@link android.view.MotionEvent#BUTTON_SECONDARY} (for primary stylus button press),
{@link android.view.MotionEvent#BUTTON_TERTIARY} (for secondary stylus button press), or both.
</li>
</ul>

<h2 id="ble-scanning">Improved Bluetooth Low Energy Scanning</h2>
<p>
If your app performs performs Bluetooth Low Energy scans, use the new
{@link android.bluetooth.le.ScanSettings.Builder#setCallbackType(int) setCallbackType()}
method to specify that you want the system to notify callbacks when it first finds, or sees after a
long time, an advertisement packet matching the set {@link android.bluetooth.le.ScanFilter}. This
approach to scanning is more power-efficient than what’s provided in the previous platform version.
</p>

<h2 id="hotspot">Hotspot 2.0 Release 1 Support</h2>
<p>
This preview adds support for the Hotspot 2.0 Release 1 spec on Nexus 6 and Nexus 9 devices. To
provision Hotspot 2.0 credentials in your app, use the new methods of the
{@link android.net.wifi.WifiEnterpriseConfig} class, such as
{@link android.net.wifi.WifiEnterpriseConfig#setPlmn(java.lang.String) setPlmn()} and
{@link android.net.wifi.WifiEnterpriseConfig#setRealm(java.lang.String) setRealm()}. In the
{@link android.net.wifi.WifiConfiguration} object, you can set the
{@link android.net.wifi.WifiConfiguration#FQDN} and the
{@link android.net.wifi.WifiConfiguration#providerFriendlyName} fields.
The new {@link android.net.wifi.ScanResult#isPasspointNetwork()} method indicates if a detected
network represents a Hotspot 2.0 access point.
</p>

<h2 id="4K-display">4K Display Mode</h2>
<p>The platform now allows apps to request that the display resolution be upgraded to 4K rendering
on compatible hardware. To query the current physical resolution, use the new
{@link android.view.Display.Mode} APIs. If the UI is drawn at a lower logical resolution and is
upscaled to a larger physical resolution, be aware that the physical resolution the
{@link android.view.Display.Mode#getPhysicalWidth()} method returns may differ from the logical
resolution reported by {@link android.view.Display#getSize(android.graphics.Point) getSize()}.</p>

<p>You can request the system to change the physical resolution in your app as it runs, by setting
the {@link android.view.WindowManager.LayoutParams#preferredDisplayModeId} property of your app’s
window.  This feature is useful if you want to switch to 4K display resolution. While in 4K display
mode, the UI continues to be rendered at the original resolution (such as 1080p) and is upscaled to
4K, but {@link android.view.SurfaceView} objects may show content at the native resolution.</p>

<h2 id="behavior-themeable-colorstatelists">Themeable ColorStateLists</h2>
<p>Theme attributes are now supported in
{@link android.content.res.ColorStateList} for devices running the M Preview. The
{@link android.content.res.Resources#getColorStateList(int) getColorStateList()} and
{@link android.content.res.Resources#getColor(int) getColor()} methods have been deprecated. If
you are calling these APIs, call the new
{@link android.content.Context#getColorStateList(int) getColorStateList()} or
{@link android.content.Context#getColor(int) getColor()} methods instead. These methods are also
available in the v4 appcompat library via {@link android.support.v4.content.ContextCompat}.</p>

<h2 id="audio">Audio Features</h2>

<p>This preview adds enhancements to audio processing on Android, including: </p>
<ul>
  <li>Support for the <a href="http://en.wikipedia.org/wiki/MIDI" class="external-link">MIDI</a>
protocol, with the new {@link android.media.midi} APIs. Use these APIs to send and receive MIDI
events.</li>
  <li>New {@link android.media.AudioRecord.Builder} and {@link android.media.AudioTrack.Builder}
classes to create digital audio capture and playback objects respectively, and configure audio
source and sink properties to override the system defaults.</li>
  <li>API hooks for associating audio and input devices. This is particularly useful if your app
allows users to start a voice search from a game controller or remote control connected to Android
TV. The system invokes the new
{@link android.app.Activity#onSearchRequested(android.view.SearchEvent) onSearchRequested()}
callback when the user starts a search. To determine if the user's input device has a built-in
microphone, retrieve the {@link android.view.InputDevice} object from that callback, then call the
new {@link android.view.InputDevice#hasMicrophone()} method.</li>
  <li>New {@link android.media.AudioManager#getDevices(int) getDevices()} method which lets you
retrieve a list of all audio devices currently connected to the system. You can also register an
{@link android.media.AudioDeviceCallback} object if you want the system to notify your app
when an audio device connects or disconnects.</li>
</ul>

<h2 id="video">Video Features</h2>
<p>This preview adds new capabilities to the video processing APIs, including:</p>
<ul>
<li>New {@link android.media.MediaSync} class which helps applications to synchronously render
audio and video streams. The audio buffers are submitted in non-blocking fashion and are
returned via a callback. It also supports dynamic playback rate.
</li>
<li>New {@link android.media.MediaDrm#EVENT_SESSION_RECLAIMED} event, which indicates that a
session opened by the app has been reclaimed by the resource manager. If your app uses DRM sessions,
you should handle this event and make sure not to use a reclaimed session.
</li>
<li>New {@link android.media.MediaCodec.CodecException#ERROR_RECLAIMED} error code, which indicates
that the resource manager reclaimed the media resource used by the codec. With this exception, the
codec must be released, as it has moved to terminal state.
</li>
<li>New {@link android.media.MediaCodecInfo.CodecCapabilities#getMaxSupportedInstances()
getMaxSupportedInstances()} interface to get a hint for the max number of the supported
concurrent codec instances.
</li>
<li>New {@link android.media.MediaPlayer#setPlaybackParams(android.media.PlaybackParams)
setPlaybackParams()} method to set the media playback rate for fast or
slow motion playback. It also stretches or speeds up the audio playback automatically in
conjunction with the video.</li>
</ul>

<h2 id="camera">Camera Features</h2>
<p>This preview includes the following new APIs for accessing the camera’s flashlight and for
camera reprocessing of images:</p>

<h3 id="flashlight">Flashlight API</h3>
<p>If a camera device has a flash unit, you can call the
{@link android.hardware.camera2.CameraManager#setTorchMode(java.lang.String, boolean) setTorchMode()}
method to switch the flash unit’s torch mode on or off without opening the camera device. The app
does not have exclusive ownership of the flash unit or the camera device. The torch mode is turned
off and becomes unavailable whenever the camera device becomes unavailable, or when other camera
resources keeping the torch on become unavailable. Other apps can also call
{@link android.hardware.camera2.CameraManager#setTorchMode(java.lang.String, boolean) setTorchMode()}
to turn off the torch mode. When the last app that turned on the torch mode is closed, the torch
mode is turned off.</p>

<p>You can register a callback to be notified about torch mode status by calling the
{@link android.hardware.camera2.CameraManager#registerTorchCallback(android.hardware.camera2.CameraManager.TorchCallback, android.os.Handler) registerTorchCallback()}
method. The first time the callback is registered, it is immediately called with the torch mode
status of all currently known camera devices with a flash unit. If the torch mode is turned on or
off successfully, the
{@link android.hardware.camera2.CameraManager.TorchCallback#onTorchModeChanged(java.lang.String, boolean) onTorchModeChanged()}
method is invoked.</p>

<h3 id="reprocessing">Reprocessing API</h3>
<p>The {@link android.hardware.camera2 Camera2} API is extended to support YUV and private
opaque format image reprocessing. To determine if these reprocessing capabilities are available,
call {@link android.hardware.camera2.CameraManager#getCameraCharacteristics(java.lang.String)
getCameraCharacteristics()} and check for the
{@link android.hardware.camera2.CameraCharacteristics#REPROCESS_MAX_CAPTURE_STALL} key. If a
device supports reprocessing, you can create a reprocessable camera capture session by calling
<a href="/reference/android/hardware/camera2/CameraDevice.html#createReprocessableCaptureSession(android.hardware.camera2.params.InputConfiguration, java.util.List<android.view.Surface>, android.hardware.camera2.CameraCaptureSession.StateCallback, android.os.Handler)"><code>createReprocessableCaptureSession()</code></a>,
and create requests for input buffer reprocessing.</p>

<p>Use the {@link android.media.ImageWriter} class to connect the input buffer flow to the camera
reprocessing input. To get an empty buffer, follow this programming model:</p>

<ol>
<li>Call the {@link android.media.ImageWriter#dequeueInputImage()} method.</li>
<li>Fill the data into the input buffer.</li>
<li>Send the buffer to the  camera by calling the
{@link android.media.ImageWriter#queueInputImage(android.media.Image) queueInputImage()} method.</li>
</ol>

<p>If you are using a {@link android.media.ImageWriter} object together with an
{@link android.graphics.ImageFormat#PRIVATE} image, your app cannot access the image
data directly. Instead, pass the {@link android.graphics.ImageFormat#PRIVATE} image directly to the
{@link android.media.ImageWriter} by calling the
{@link android.media.ImageWriter#queueInputImage(android.media.Image) queueInputImage()} method
without any buffer copy.</p>

<p>The {@link android.media.ImageReader} class now supports
{@link android.graphics.ImageFormat#PRIVATE} format image streams. This support allows your app to
maintain a circular image queue of {@link android.media.ImageReader} output images, select one or
more images, and send them to the {@link android.media.ImageWriter} for camera reprocessing.</p>

<h2 id="afw">Android for Work Features</h2>
<p>This preview includes the following new APIs for Android for Work:</p>
<ul>
  <li><strong>Enhanced controls for Corporate-Owned, Single-Use devices:</strong> The Device Owner
can now control the following settings to improve management of
Corporate-Owned, Single-Use (COSU) devices:
  <ul>
    <li>Disable or re-enable the keyguard with the
{@link android.app.admin.DevicePolicyManager#setKeyguardDisabled(android.content.ComponentName, boolean)
setKeyguardDisabled()} method.</li>
    <li>Disable or re-enable the status bar (including quick settings, notifications, and the
navigation swipe-up gesture that launches Google Now) with the
{@link android.app.admin.DevicePolicyManager#setStatusBarDisabled(android.content.ComponentName, boolean) setStatusBarDisabled()}
method.</li>
    <li>Disable or re-enable safe boot with the {@link android.os.UserManager} constant
{@link android.os.UserManager#DISALLOW_SAFE_BOOT}.</li>
    <li>Prevent the screen from turning off while plugged in with the
  {@link android.provider.Settings.Global#STAY_ON_WHILE_PLUGGED_IN} constant.</li>
  </ul>
  </li>
  <li><strong>Silent install and uninstall of apps by Device Owner:</strong> A Device Owner can now
silently install and uninstall applications using the {@link android.content.pm.PackageInstaller}
APIs, independent of Google Play for Work. You can now provision devices through a Device Owner that
fetches and installs apps without user interaction. This feature is useful for enabling one-touch
provisioning of kiosks or other such devices without activating a Google account.</li>
<li><strong>Silent enterprise certificate access: </strong> When an app calls
{@link android.security.KeyChain#choosePrivateKeyAlias(android.app.Activity,android.security.KeyChainAliasCallback,java.lang.String[],java.security.Principal[],java.lang.String,int,java.lang.String) choosePrivateKeyAlias()},
prior to the user being prompted to select a certificate, the Profile or Device Owner can now call
the {@link android.app.admin.DeviceAdminReceiver#onChoosePrivateKeyAlias(android.content.Context, android.content.Intent, int, android.net.Uri, java.lang.String) onChoosePrivateKeyAlias()}
method to provide the alias silently to the requesting application. This feature lets you grant
managed apps access to certificates without user interaction.</li>
<li><strong>Auto-acceptance of system updates.</strong> By setting a system update policy with
{@link android.app.admin.DevicePolicyManager#setSystemUpdatePolicy(android.content.ComponentName, android.app.admin.SystemUpdatePolicy) setSystemUpdatePolicy()},
a Device Owner can now auto-accept a system
update, for instance in the case of a kiosk device, or postpone the update and prevent it being
taken by the user for up to 30 days. Furthermore, an administrator can set a daily time window in
which an update must be taken, for example during the hours when a kiosk device is not in use. When
a system update is available, the system checks if the Work Policy Controller app has set a system
update policy, and behaves accordingly.
</li>
<li>
<strong>Delegated certificate installation:</strong> A Profile or Device Owner can now grant a
third-party app the ability to call these {@link android.app.admin.DevicePolicyManager} certificate
management APIs:
<ul>
  <li>{@link android.app.admin.DevicePolicyManager#getInstalledCaCerts(android.content.ComponentName)
getInstalledCaCerts()}</li>
  <li>{@link android.app.admin.DevicePolicyManager#hasCaCertInstalled(android.content.ComponentName,byte[])
hasCaCertInstalled()}</li>
  <li>{@link android.app.admin.DevicePolicyManager#installCaCert(android.content.ComponentName,byte[])
installCaCert()}</li>
  <li>{@link android.app.admin.DevicePolicyManager#uninstallCaCert(android.content.ComponentName,byte[])
uninstallCaCert()}</li>
  <li>{@link android.app.admin.DevicePolicyManager#uninstallAllUserCaCerts(android.content.ComponentName)
uninstallAllUserCaCerts()}</li>
  <li>{@link android.app.admin.DevicePolicyManager#installKeyPair(android.content.ComponentName,java.security.PrivateKey,java.security.cert.Certificate,java.lang.String)
installKeyPair()}</li>
</ul>
</li>
<img src="{@docRoot}preview/images/work-profile-screen.png"
srcset="{@docRoot}preview/images/work-profile-screen.png 1x, {@docRoot}preview/images/work-profile-screen_2x.png 2x"
style="float:right; margin:0 0 10px 20px" width="282" height="476" />
<li><strong>Data usage tracking.</strong> A Profile or Device Owner can now query for the
data usage statistics visible in <strong>Settings > Data</strong> usage by using the new
{@link android.app.usage.NetworkStatsManager} methods. Profile Owners are automatically granted
permission to query data on the profile they manage, while Device Owners get access to usage data
of the managed primary user.</li>
<li><strong>Runtime permission management:</strong>
<p>A Profile or Device Owner can set a permission policy
for all runtime requests of all applications using
{@link android.app.admin.DevicePolicyManager#setPermissionPolicy(android.content.ComponentName, int)
setPermissionPolicy()}, to either prompt the user to grant the permission or automatically grant or
deny the permission silently. If the latter policy is set, the user cannot
modify the selection made by the Profile or Device Owner within the app’s permissions screen in
<strong>Settings</strong>.</p></li>
<li><strong>VPN in Settings:</strong> VPN apps are now visible in
    <strong>Settings > More > VPN</strong>.
Additionally, the notifications that accompany VPN usage are now specific to how that VPN is
configured. For Profile Owner, the notifications are specific to whether the VPN is configured
for a managed profile, a personal profile, or both. For a Device Owner, the notifications are
specific to whether the VPN is configured for the entire device.</li>
<li><strong>Work status notification:</strong> A status bar briefcase icon now appears whenever
an app from the managed profile has an activity in the foreground. Furthermore, if the device is
unlocked directly to the activity of an app in the managed profile, a toast is displayed notifying
the user that they are within the work profile.
</li>
</ul>

<p class="note">
  For a detailed view of all API changes in the M Developer Preview, see the <a href=
  "{@docRoot}preview/download.html">API Differences Report</a>.
</p>