android_frameworks_base/docs/html/training/tv/tif/tvinput.jd

page.title=Developing a TV Input Service
page.tags=tv, tif
helpoutsWidget=true

trainingnavtop=true

@jd:body

<div id="tb-wrapper">
<div id="tb">
  <h2>This lesson teaches you to</h2>
  <ol>
    <li><a href="#manifest">Declare Your TV Input Service in the Manifest</a></li>
    <li><a href="#tvinput">Define Your TV Input Service</a></li>
    <li><a href="#setup">Define Setup and Settings Activities</a></li>
  </ol>
  <h2>You should also read</h2>
  <ul>
    <li><a href="{@docRoot}reference/android/media/tv/package-summary.html">
      android.media.tv</a></li>
    <li><a class="external-lin" href="http://source.android.com/devices/tv/index.html">
      TV Input Framework</a></li>
  </ul>
  <h2>Try It Out</h2>
  <ul>
    <li><a class="external-link" href="https://github.com/googlesamples/androidtv-sample-inputs">
      TV Input Service sample app</a></li>
  </ul>
</div>
</div>

<p>A TV input service represents a media stream source, and lets you present your media content in a
linear, broadcast TV fashion as channels and programs. With the TV input service, you can provide
parental controls, program guide information, and content ratings. The TV input service works
with the Android system TV app, developed for the device and immutable by third-party apps, which
ultimately controls and presents content on the TV. See
<a class="external-link" href="http://source.android.com/devices/tv/index.html">
TV Input Framework</a> for more information about the framework architecture and its components.</p>

<p>To develop a TV input service, you implement the following components:</p>

<ul>
  <li>{@link android.media.tv.TvInputService} provides long-running and background availability for
  the TV input</li>
  <li>{@link android.media.tv.TvInputService.Session} maintains the TV input state and communicates
  with the hosting app</li>
  <li>{@link android.media.tv.TvContract} describes the channels and programs available to the TV
  input</li>
  <li>{@link android.media.tv.TvContract.Channels} represents information about a TV channel</li>
  <li>{@link android.media.tv.TvContract.Programs} describes a TV program with data such as program
  title and start time</li>
  <li>{@link android.media.tv.TvTrackInfo} represents an audio, video, or subtitle track</li>
  <li>{@link android.media.tv.TvContentRating} describes a content rating, allows for custom content
  rating schemes</li>
  <li>{@link android.media.tv.TvInputManager} provides an API to the system TV app and manages
  the interaction with TV inputs and apps</li>
</ul>

<h2 id="manifest">Declare Your TV Input Service in the Manifest</h2>

<p>Your app manifest must declare your {@link android.media.tv.TvInputService}. Within that
declaration, specify the {@link android.Manifest.permission#BIND_TV_INPUT} permission to allow the
service to connect the TV input to the system. A system service (<code>TvInputManagerService</code>)
performs the binding and has that permission. The system TV app sends requests to TV input services
via the {@link android.media.tv.TvInputManager} interface. The service declaration must also
include an intent filter that specifies the {@link android.media.tv.TvInputService}
as the action to perform with the intent. Also within the service declaration, declare the service
meta data in a separate XML resource. The service declaration, the intent filter and the service
meta data are described in the following example.</p>

<pre>
&lt;service android:name="com.example.sampletvinput.SampleTvInput"
    android:label="@string/sample_tv_input_label"
    android:permission="android.permission.BIND_TV_INPUT"&gt;
    &lt;intent-filter&gt;
        &lt;action android:name="android.media.tv.TvInputService" /&gt;
    &lt;/intent-filter&gt;
    &lt;meta-data android:name="android.media.tv.input"
      android:resource="@xml/sample_tv_input" /&gt;
&lt;/service&gt;
</pre>

<p>Define the service meta data in separate XML file, as shown in the following example. The service
meta data must include a setup interface that describes the TV input's initial configuration and
channel scan. Also, the service meta data may (optionally) describe a settings activity for users to
modify the TV input's behavior. The service meta data file is located in the XML resources directory
for your application and must match the name of the resource in the manifest. Using the example
manifest entries above, you would create an XML file in the location
<code>res/xml/sample_tv_input.xml</code>, with the following contents:</p>

<pre>
&lt;tv-input xmlns:android="http://schemas.android.com/apk/res/android"
  &lt;!-- Required: activity for setting up the input --&gt;
  android:setupActivity="com.example.sampletvinput.SampleTvInputSetupActivity"
  &lt;!-- Optional: activity for controlling the settings --&gt;
  android:settingsActivity="com.example.sampletvinput.SampleTvInputSettingsActivity" /&gt;
</pre>

<h2 id="tvinput">Define Your TV Input Service</h2>

<div class="figure">
<img id="tvinputlife" src="{@docRoot}images/tv/tvinput-life.png" alt=""/>
<p class="img-caption"><strong>Figure 1.</strong>TvInputService lifecycle.</p>
</div>

<p>For your service, you extend the {@link android.media.tv.TvInputService} class. A
{@link android.media.tv.TvInputService} implementation is a
<a href="{@docRoot}guide/components/bound-services.html">bound service</a> where the system service
(<code>TvInputManagerService</code>) is the client that binds to it. The service life cycle methods
you need to implement are illustrated in figure 1.</p>

<p>The {@link android.app.Service#onCreate()} method initializes and starts the
{@link android.os.HandlerThread} which provides a process thread separate from the UI thread to
handle system-driven actions. In the following example, the {@link android.app.Service#onCreate()}
method initializes the {@link android.view.accessibility.CaptioningManager} and prepares to handle
the {@link android.media.tv.TvInputManager#ACTION_BLOCKED_RATINGS_CHANGED}
and {@link android.media.tv.TvInputManager#ACTION_PARENTAL_CONTROLS_ENABLED_CHANGED} actions. These
actions describe system intents fired when the user changes the parental control settings, and when
there is a change on the list of blocked ratings.</p>

<pre>
&#64;Override
public void onCreate() {
    super.onCreate();
    mHandlerThread = new HandlerThread(getClass()
      .getSimpleName());
    mHandlerThread.start();
    mDbHandler = new Handler(mHandlerThread.getLooper());
    mHandler = new Handler();
    mCaptioningManager = (CaptioningManager)
      getSystemService(Context.CAPTIONING_SERVICE);

    setTheme(android.R.style.Theme_Holo_Light_NoActionBar);

    mSessions = new ArrayList&lt;BaseTvInputSessionImpl&gt;();
    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction(TvInputManager
      .ACTION_BLOCKED_RATINGS_CHANGED);
    intentFilter.addAction(TvInputManager
      .ACTION_PARENTAL_CONTROLS_ENABLED_CHANGED);
    registerReceiver(mBroadcastReceiver, intentFilter);
}
</pre>

<p> See <a href="{@docRoot}training/tv/tif/ui.html#control">
Control Content</a> for more information about working with blocked content and providing
parental control. See {@link android.media.tv.TvInputManager} for more system-driven actions that
you may want to handle in your TV input service.</p>

<p>The {@link android.media.tv.TvInputService} creates a
{@link android.media.tv.TvInputService.Session} that implements {@link android.os.Handler.Callback}
to handle player state changes. With {@link android.media.tv.TvInputService.Session#onSetSurface(android.view.Surface) onSetSurface()},
the {@link android.media.tv.TvInputService.Session} sets the {@link android.view.Surface} with the
video content. See <a href="{@docRoot}training/tv/tif/ui.html#surface">Integrate Player with Surface</a>
for more information about working with {@link android.view.Surface} to render video.</p>

<p>The {@link android.media.tv.TvInputService.Session} handles the
{@link android.media.tv.TvInputService.Session#onTune(android.net.Uri) onTune()}
event when the user selects a channel, and notifies the system TV app for changes in the content and
content meta data. These <code>notify()</code>code> methods are described in
<a href="{@docRoot}training/tv/tif/ui.html#control">
Control Content</a> and <a href="training/tv/tif/ui.html#track">Handle Track Selection</a> further
in this training.</p>

<h2 id="setup">Define Setup and Settings Activities</h2>

<p>The system TV app works with the setup and settings activities you define for your TV input. The
setup activity is required and must provide at least one channel record for the system database. The
system TV app will invoke the setup activity when it cannot find a channel for the TV input.
<p>The setup activity describes to the system TV app the channels made available through the TV
input, as demonstrated in the next lesson, <a href="{@docRoot}training/tv/tif/channel.html">Creating
and Updating Channel Data</a>.</p>

<p>The settings activity is optional. You can define a settings activity to turn on parental
controls, enable closed captions, set the display attributes, and so forth.</p>