android_frameworks_base/docs/html/training/tv/start/hardware.jd

page.title=Handling TV Hardware
page.tags="unsupported"
trainingnavtop=true

@jd:body

<div id="tb-wrapper">
<div id="tb">
  <h2>This lesson teaches you how to</h2>
  <ol>
    <li><a href="#runtime-check">Check for a TV Device</a>
    <li><a href="#handle-features">Handle Unsupported Hardware Features</a></li>
    <li><a href="#controllers">Manage Hardware Controllers</a>
    </li>
  </ol>
</div>
</div>

<p>
  TV hardware is substantially different from other Android devices. TVs do not
  include some of the hardware features found on other Android devices, such as touch screens,
  cameras, and GPS receivers. TVs are also completely dependent on secondary hardware devices.
  In order for users to interact with TV apps, they must use a remote control or game pad. When
  you build an app for TV, you must carefully consider the hardware limitations and requirements of
  operating on TV hardware.
</p>

<p>
  This lesson discusses how to check if your app is running on a TV, how to handle unsupported
  hardware features, and discusses the requirements for handling controllers for TV devices.
</p>


<h2 id="runtime-check">Check for a TV Device</h2>

<p>
  If you are building an app that operates both on TV devices and other devices, you may need to
  check what kind of device your app is running on and adjust the operation of your app. For
  instance, if you have an app that can be started through an {@link android.content.Intent}, your
  application should check the device properties to determine if it should start a TV-oriented
  activity or a phone activity.
</p>

<p>
  The recommended way to determine if your app is running on a TV device is to use the {@link
  android.app.UiModeManager#getCurrentModeType UiModeManager.getCurrentModeType()} method to check
  if the device is running in television mode. The following example code shows you how to check if
  your app is running on a TV device:
</p>

<pre>
public static final String TAG = "DeviceTypeRuntimeCheck";

UiModeManager uiModeManager = (UiModeManager) getSystemService(UI_MODE_SERVICE);
if (uiModeManager.getCurrentModeType() == Configuration.UI_MODE_TYPE_TELEVISION) {
    Log.d(TAG, "Running on a TV Device")
} else {
    Log.d(TAG, "Running on a non-TV Device")
}
</pre>


<h2 id="handle-features">Handle Unsupported Hardware Features</h2>

<p>
  Depending on the design and functionality of your app, you may be able to work around certain
  hardware features being unavailable. This section discusses what hardware features are typically
  not available for TV, how to detect missing hardware features, and suggests alternatives to
  using these features.
</p>


<h3 id="unsupported-features">Unsupported TV hardware features</h3>

<p>
  TVs have a different purpose from other devices, and so they do not have hardware features that
  other Android-powered devices often have. For this reason, the Android system does not support
  the following features for a TV device:
</p>

<table>
  <tr>
    <th>Hardware</th>
    <th>Android feature descriptor</th>
  </tr>
  <tr>
    <td>Touchscreen</td>
    <td>{@code android.hardware.touchscreen}</td>
  </tr>
  <tr>
    <td>Touchscreen emulator</td>
    <td>{@code android.hardware.faketouch}</td>
  </tr>
  <tr>
    <td>Telephony</td>
    <td>{@code android.hardware.telephony}</td>
  </tr>
  <tr>
    <td>Camera</td>
    <td>{@code android.hardware.camera}</td>
  </tr>
  <tr>
    <td>Bluetooth</td>
    <td>{@code android.hardware.bluetooth}</td>
  </tr>
  <tr>
    <td>Near Field Communications (NFC)</td>
    <td>{@code android.hardware.nfc}</td>
  </tr>
  <tr>
    <td>GPS</td>
    <td>{@code android.hardware.location.gps}</td>
  </tr>
  <tr>
    <td>Microphone <sup><a href="#cont-mic">[1]</a></sup></td>
    <td>{@code android.hardware.microphone}</td>
  </tr>
  <tr>
    <td>Sensors</td>
    <td>{@code android.hardware.sensor}</td>
  </tr>
</table>

<p id="cont-mic" class="note">
  <strong>[1]</strong> Some TV controllers have a microphone, which is
  not the same as the microphone hardware feature described here. The controller microphone is fully
  supported.
</p>

<p>
  See the <a href="{@docRoot}guide/topics/manifest/uses-feature-element.html#features-reference">
  Features Reference</a> for a complete list of features, subfeatures, and their descriptors.
</p>


<h3 id="declare-hardware-requirements">Declaring hardware requirements for TV</h3>

<p>
  Android apps can declare hardware feature requirements in the app manifest to ensure that they do
  not get installed on devices that do not provide those features. If you are extending an existing
  app for use on TV, closely review your app's manifest for any hardware requirement
  declarations that might prevent it from being installed on a TV device.
</p>

<p>
  If your app uses hardware features (such as a touchscreen or camera) that are not available on
  TV, but can operate without the use of those features, modify your app's manifest to
  indicate that these features are not required by your app. The following manifest code snippet
  demonstrates how to declare that your app does not require hardware features which are unavailable
  on TV devices, even though your app may use these features on non-TV devices:
</p>

<pre>
&lt;uses-feature android:name="android.hardware.touchscreen"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.faketouch"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.telephony"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.camera"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.bluetooth"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.nfc"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.gps"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.microphone"
        android:required="false"/&gt;
&lt;uses-feature android:name="android.hardware.sensor"
        android:required="false"/&gt;
</pre>

<p class="note"><strong>Note:</strong> Some features have subfeatures like {@code android.hardware.camera.front},
  as described in the <a href="guide/topics/manifest/uses-feature-element.html#features-reference">
  Feature Reference</a>. Be sure to mark as {@code required="false"} any subfeatures also used in
  your app.</p>

<p>
  All apps intended for use on TV devices must declare that the touch screen feature is not required
  as described in <a href="{@docRoot}training/tv/start/start.html#no-touchscreen">Get Started with
  TV Apps</a>. If your app normally uses one or more of the features listed above, change the
  {@code android:required} attribute setting to {@code false} for those features in your manifest.
</p>

<p class="caution">
  <strong>Caution:</strong> Declaring a hardware feature as required by setting its
  value to {@code true}  prevents your app from being installed on TV
  devices or appearing in the Android TV home screen launcher.
</p>

<p>
  Once you decide to make hardware features optional for your app, you must check for the
  availability of those features at runtime and then adjust your app's behavior. The next section
  discusses how to check for hardware features and suggests some approaches for changing the
  behavior of your app.
</p>

<p>
  For more information on filtering and declaring features in the manifest, see the
  <a href="{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code uses-feature}</a>
  guide.
</p>


<h3 id="hardware-permissions">Declaring permissions that imply hardware features</h3>

<p>
  Some <a href="{@docRoot}guide/topics/manifest/uses-permission-element.html">{@code uses-permission}</a>
  manifest declarations <em>imply hardware features</em>. This behavior means that requesting some
  permissions in your app manifest can exclude your app from from being installed and used on TV
  devices. The following commonly requested permissions create an implicit hardware feature
  requirement:
</p>

<table>
  <tr>
    <th>Permission</th>
    <th>Implied hardware feature</th>
  </tr>
  <tr>
    <td>{@link android.Manifest.permission#RECORD_AUDIO}</td>
    <td>{@code android.hardware.microphone}</td>
  </tr>
  <tr>
    <td>{@link android.Manifest.permission#CAMERA}</td>
    <td>{@code android.hardware.camera} <em>and</em> <br>
      {@code android.hardware.camera.autofocus}</td>
  </tr>
  <tr>
    <td>{@link android.Manifest.permission#ACCESS_COARSE_LOCATION}</td>
    <td>{@code android.hardware.location} <em>and</em> <br>
      {@code android.hardware.location.network}</td>
  </tr>
  <tr>
    <td>{@link android.Manifest.permission#ACCESS_FINE_LOCATION}</td>
    <td>{@code android.hardware.location} <em>and</em> <br>
      {@code android.hardware.location.gps}</td>
  </tr>
</table>

<p>
  For a complete list of permission requests that imply a hardware feature requirement, see the
  <a href="{@docRoot}guide/topics/manifest/uses-feature-element.html#permissions-features">{@code
  uses-feature}</a> guide. If your app requests one of the features listed above, include a
  <a href="{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code uses-feature}</a>
  declaration in your manifest for the implied hardware feature that indicates it is not
  required ({@code android:required="false"}).
</p>


<h3 id="check-features">Checking for hardware features</h2>

<p>
  The Android framework can tell you if hardware features are not available on the device where
  your app is running. Use the {@link android.content.pm.PackageManager#hasSystemFeature(String)}
  method to check for specific features at runtime. This method takes a single string argument that
  specifies the feature you want to check.
</p>

<p>The following code example demonstrates how to detect the availability of hardware features
  at runtime:</p>

<pre>
// Check if the telephony hardware feature is available.
if (getPackageManager().hasSystemFeature("android.hardware.telephony")) {
    Log.d("HardwareFeatureTest", "Device can make phone calls");
}

// Check if android.hardware.touchscreen feature is available.
if (getPackageManager().hasSystemFeature("android.hardware.touchscreen")) {
    Log.d("HardwareFeatureTest", "Device has a touch screen.");
}
</pre>


<h4 id="no-touchscreen">Touch screen</h4>

<p>
  Since most TVs do not have touch screens, Android does not support touch screen interaction for
  TV devices. Furthermore, using a touch screen is not consistent with a viewing environment where
  the user is seated 10 feet away from the display. Make sure that your UI elements and text do not
  require or imply the use of a touchscreen.
</p>

<p>
  On TV devices, you should design your app to work with this interaction model by supporting
  navigation using a directional pad (D-pad) on a TV remote control. For more information on
  properly supporting navigation using TV-friendly controls, see
  <a href="{@docRoot}training/tv/start/navigation.html">Creating TV Navigation</a>.
</p>


<h4 id="no-camera">Camera</h4>

<p>
  Although a TV typically does not have a camera, you can still provide a photography-related
  app on a TV. For example, if you have an app that takes, views, and edits photos, you can
  disable its picture-taking functionality for TVs and still allow users to view and even edit
  photos. If you decide to enable your camera-related app to work on a TV, add the
  following feature declaration your app manifest:
</p>

<pre>
&lt;uses-feature android:name="android.hardware.camera" android:required="false" /&gt;
</pre>

<p>
  If you enable your app to run without a camera, add code to your app
  that detects if the camera feature is available and makes adjustments to the operation of your
  app. The following code example demonstrates how to detect the presence of a camera:
</p>

<pre>
// Check if the camera hardware feature is available.
if (getPackageManager().hasSystemFeature("android.hardware.camera")) {
    Log.d("Camera test", "Camera available!");
} else {
    Log.d("Camera test", "No camera available. View and edit features only.");
}
</pre>


<h4 id="no-gps">GPS</h4>

<p>
  TVs are stationary, indoor devices, and do not have built-in global positioning system (GPS)
  receivers. If your app uses location information, you can still allow users to search for
  a location, or use a static location provider such as a zip code configured during the TV device
  setup.
</p>

<pre>
// Request a static location from the location manager
LocationManager locationManager = (LocationManager) this.getSystemService(
        Context.LOCATION_SERVICE);
Location location = locationManager.getLastKnownLocation("static");

// Attempt to get postal or zip code from the static location object
Geocoder geocoder = new Geocoder(this);
Address address = null;
try {
  address = geocoder.getFromLocation(location.getLatitude(),
          location.getLongitude(), 1).get(0);
  Log.d("Zip code", address.getPostalCode());

} catch (IOException e) {
  Log.e(TAG, "Geocoder error", e);
}
</pre>


<h2 id="controllers">Handling Controllers</h2>

<p>
  TV devices require a secondary hardware device for interacting with apps, in the form of a basic
  remote controller or game controller. This means that your app must support D-pad input. It also
  means that your app may need to handle controllers going offline and input from more than one
  type of controller.
</p>


<h3 id="d-pad-minimum">D-pad minimum controls</h3>

<p>
  The default controller for a TV device is a D-pad. In general, your app should be operable from a
  remote controller that only has up, down, left, right, select, Back, and Home buttons. If your app
  is a game that typically requires a game controller with additional controls, your app should
  attempt to allow gameplay with these D-pad controls. In this case, your app should also warn the
  user that
  a controller is required and allow them to exit your game gracefully using the D-pad controller.
  For more information about handling navigation with D-pad controller for TV devices, see
  <a href="{@docRoot}training/tv/start/navigation.html">Creating TV Navigation</a>.
</p>


<h3 id="controller-disconnects">Handle controller disconnects</h3>

<p>
  Controllers for TV are frequently Bluetooth devices which may attempt to save power by periodically
  going into sleep mode and disconnecting from the TV device. This means that an app might be
  interrupted or restarted if it is not configured to handle these reconnect events. These events
  can happen in any of the following circumstances:
</p>

<ul>
  <li>While watching a video which is several minutes long, a D-Pad or game controller goes into
  sleep mode, disconnects from the TV device and then reconnects later on.
  </li>
  <li>During gameplay, a new player joins the game using a game controller that is not currently
  connected.
  </li>
  <li>During gameplay, a player leaves the game and disconnects a game controller.
  </li>
</ul>

<p>
  Any TV app activity that is subject to disconnect and reconnect events must be configured to
  handle reconnection events in the app manifest. The following code sample demonstrates how to
  enable an activity to handle configuration changes, including a keyboard or navigation device
  connecting, disconnecting, or reconnecting:
</p>

<pre>
&lt;activity
  android:name=&quot;com.example.android.TvActivity&quot;
  android:label=&quot;&#64;string/app_name&quot;
  <strong>android:configChanges="keyboard|keyboardHidden|navigation"</strong>
  android:theme=&quot;&#64;style/Theme.Leanback&quot;&gt;

  &lt;intent-filter&gt;
    &lt;action android:name=&quot;android.intent.action.MAIN&quot; /&gt;
    &lt;category android:name="android.intent.category.LEANBACK_LAUNCHER" /&gt;
  &lt;/intent-filter&gt;
  ...
&lt;/activity&gt;
</pre>

<p>
  This configuration change allows the app to continue running through a reconnection event, rather
  than being restarted by the Android framework, which is not a good user experience.
</p>


<h3 id="d-pad-variants">Handle D-pad input variations</h3>

<p>
  TV device users may have more than one type of controller that they use with their TV. For
  example, a user might have both a basic D-pad controller and a game controller. The key codes
  provided by a game controller when it is being used for D-pad functions may vary from the key
  codes sent by a physical D-pad.
</p>

<p>
  Your app should handle the variations of D-pad input from a game controller, so the user does not
  have to physically switch controllers to operate your app. For more information on handling these
  input variations, see <a href="{@docRoot}training/game-controllers/controller-input.html#dpad">
  Handling Controller Actions</a>.
</p>