Merge "docs: ATV Catalog Browser Update" into lmp-docs

<p>These classes teach you how to build apps for TV devices.</p>

<p class="note"><strong>Note:</strong> For details on how to publish your TV apps in Google Play,  see <a href="{docRoot}distribute/googleplay/tv.html">Distributing to Android TV</a>.</p>

 No newline at end of file

<p class="note"><strong>Note:</strong> For details on how to publish your TV

apps in Google Play, see <a href="{@docRoot}distribute/googleplay/tv.html">

Distributing to Android TV</a>.</p>

 No newline at end of file

  <h2>This lesson teaches you to</h2>

  <ol>

    <li><a href="#layout">Create a Media Browse Layout</a></li>

    <li><a href="#header">Customize the Header Views</a></li>

    <li><a href="#lists">Display Media Lists</a></li>

    <li><a href="#background">Update the Background</a></li>

  </ol>

  <h2>Try it out</h2>

  <ul>

    <li><a class="external-link" href="https://github.com/googlesamples/androidtv-Leanback">Android

    Leanback sample app</a></li>

  </ul>

</div>

</div>

<p>

  Media apps that run on TV need to allow users to browse its content offerings, make a

  A media app that runs on a TV needs to allow users to browse its content offerings, make a

  selection, and start playing content. The content browsing experience for apps of this type

  should be simple and intuitive, as well as visually pleasing and engaging.

</p>

<p>

  This lesson discusses how to use the classes provided by the <a href=

  "{@docRoot}tools/support-library/features.html#v17-leanback">v17 leanback support library</a> to

  implement a user interface for browsing music or videos from your app's media catalog.

  "{@docRoot}tools/support-library/features.html#v17-leanback">v17 leanback support library</a>

  to implement a user interface for browsing music or videos from your app's media catalog.

</p>

<img itemprop="image" src="{@docRoot}images/tv/app-browse.png" alt="App main screen"/>

<p class="img-caption"><b>Figure 1.</b> The <a href="https://github.com/googlesamples/androidtv-Leanback">

Leanback sample app</a> browse fragment displays video catalog data.</p>

<h2 id="layout">Create a Media Browse Layout</h2>

  The {@link android.support.v17.leanback.app.BrowseFragment} class in the leanback library

  allows you to create a primary layout for browsing categories and rows of media items with a

  minimum of code. The following example shows how to create a layout that contains a {@link

  android.support.v17.leanback.app.BrowseFragment}:

  android.support.v17.leanback.app.BrowseFragment} object:

</p>

<pre>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

  android:layout_width="match_parent"

  android:layout_height="match_parent"

  android:orientation="vertical"

  >

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:id="@+id/main_frame"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

    <fragment

      <strong>android:name="android.support.v17.leanback.app.BrowseFragment"</strong>

      android:id="@+id/browse_fragment"

      android:layout_width="match_parent"

      android:layout_height="match_parent"

      />

        android:name="com.example.android.tvleanback.ui.MainFragment"

        android:id="@+id/main_browse_fragment"

        android:layout_width="match_parent"

        android:layout_height="match_parent" />

</FrameLayout>

</pre>

<p>The application's main activity sets this view, as shown in the following example:</p>

<pre>

public class MainActivity extends Activity {

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

    }

...

</pre>

<p>The {@link android.support.v17.leanback.app.BrowseFragment} methods populate the view with the

video data and UI elements and set the layout parameters such as the icon, title, and whether

category headers are enabled.</p>

<ul>

  <li>See <a href="#set-ui">Set UI Elements</a> for more information about setting up UI elements.</li>

  <li>See <a href="#hide-heads">Hide or Disable Headers</a> for more information about hiding the

  headers.</li>

</ul>

<p>The application's subclass that implements the

{@link android.support.v17.leanback.app.BrowseFragment} methods also sets

up event listeners for user actions on the UI elements, and prepares the background

manager, as shown in the following example:</p>

<pre>

public class MainFragment extends BrowseFragment implements

        LoaderManager.LoaderCallbacks<HashMap<String, List<Movie>>> {

...

    @Override

    public void onActivityCreated(Bundle savedInstanceState) {

        super.onActivityCreated(savedInstanceState);

        loadVideoData();

        prepareBackgroundManager();

        setupUIElements();

        setupEventListeners();

    }

...

    private void prepareBackgroundManager() {

        mBackgroundManager = BackgroundManager.getInstance(getActivity());

        mBackgroundManager.attach(getActivity().getWindow());

        mDefaultBackground = getResources()

            .getDrawable(R.drawable.default_background);

        mMetrics = new DisplayMetrics();

        getActivity().getWindowManager().getDefaultDisplay().getMetrics(mMetrics);

    }

    private void setupUIElements() {

        setBadgeDrawable(getActivity().getResources()

            .getDrawable(R.drawable.videos_by_google_banner));

        // Badge, when set, takes precedent over title

        setTitle(getString(R.string.browse_title));

        setHeadersState(HEADERS_ENABLED);

        setHeadersTransitionOnBackEnabled(true);

        // set headers background color

        setBrandColor(getResources().getColor(R.color.fastlane_background));

        // set search icon color

        setSearchAffordanceColor(getResources().getColor(R.color.search_opaque));

    }

    private void loadVideoData() {

        VideoProvider.setContext(getActivity());

        mVideosUrl = getActivity().getResources().getString(R.string.catalog_url);

        getLoaderManager().initLoader(0, null, this);

    }

    private void setupEventListeners() {

        setOnSearchClickedListener(new View.OnClickListener() {

            @Override

            public void onClick(View view) {

                Intent intent = new Intent(getActivity(), SearchActivity.class);

                startActivity(intent);

            }

        });

        setOnItemViewClickedListener(new ItemViewClickedListener());

        setOnItemViewSelectedListener(new ItemViewSelectedListener());

    }

...

</pre>

<h3 id="set-ui">Set UI Elements</h2>

<p>In the sample above, the private method <code>setupUIElements()</code> calls several of the

{@link android.support.v17.leanback.app.BrowseFragment} methods to style the media catalog browser:

</p>

<ul>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#setBadgeDrawable(android.graphics.drawable.Drawable) setBadgeDrawable()}

  places the specified drawable resource in the upper-right corner of the browse fragment, as

  shown in figures 1 and 2. This method replaces the title string with the

  drawable resource, if {@code setTitle()} is also called. The drawable resource should be 52dps

  tall.</li>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#setTitle(java.lang.String) setTitle()}

  sets the title string in the upper-right corner of the browse fragment, unless

  {@code setBadgeDrawable()} is called.</li>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#setHeadersState(int) setHeadersState()}

  and {@link android.support.v17.leanback.app.BrowseFragment#setHeadersTransitionOnBackEnabled(boolean) setHeadersTransitionOnBackEnabled()} hide or disable the headers. See

  <a href="#hide-heads">Hide or Disable Headers</a> for more information.

  </li>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#setBrandColor(int) setBrandColor()}

  sets the background color for UI elements in the browse fragment, specifically the header

  section background color, with the specified color value.</li>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#setSearchAffordanceColor(int) setSearchAffordanceColor()}

  sets the color of the search icon with the specified color value. The search icon

  appears in the upper-left corner of the browse fragment, as shown in figures 1 and 2.</li>

</ul>

<h2 id="header">Customize the Header Views</h2>

<p>The browse fragment shown in figure 1 lists the video category names (the row headers) in the

left pane. Text views display these category names from the video database. You can customize the

header to include additional views in a more complex layout. The following sections show how to

include an image view that displays an icon next to the category name, as shown in figure 2.</p>

<img itemprop="image" src="{@docRoot}images/tv/custom-head.png" alt="App main screen"/>

<p class="img-caption"><b>Figure 2.</b> The row headers in the browse fragment, with both an icon

and a text label.</p>

<p>The layout for the row header is defined as follows:</p>

<pre>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:orientation="horizontal"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

    <ImageView

        android:id="@+id/header_icon"

        android:layout_width="32dp"

        android:layout_height="32dp" />

    <TextView

        android:id="@+id/header_label"

        android:layout_marginTop="6dp"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content" />

</LinearLayout>

</pre>

<p>

  In order to work with this layout in an activity, retrieve the {@link

  android.support.v17.leanback.app.BrowseFragment} element from the layout. Use the methods in this

  class to set display parameters such as the icon, title, and whether category headers are enabled.

  The following code sample demonstrates how to set the layout parameters for a {@link

  android.support.v17.leanback.app.BrowseFragment} in a layout:

<p>Use a {@link android.support.v17.leanback.widget.Presenter} and implement the

abstract methods to create, bind, and unbind the view holder. The following

example shows how to bind the viewholder with two views, an

{@link android.widget.ImageView} and a {@link android.widget.TextView}.

</p>

<pre>

public class BrowseMediaActivity extends Activity {

public class IconHeaderItemPresenter extends Presenter {

    @Override

    public ViewHolder onCreateViewHolder(ViewGroup viewGroup) {

        LayoutInflater inflater = (LayoutInflater) viewGroup.getContext()

                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    public static final String TAG ="BrowseActivity";

        View view = inflater.inflate(R.layout.icon_header_item, null);

    protected BrowseFragment mBrowseFragment;

        return new ViewHolder(view);

    }

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.browse_fragment);

    public void onBindViewHolder(ViewHolder viewHolder, Object o) {

        HeaderItem headerItem = ((ListRow) o).getHeaderItem();

        View rootView = viewHolder.view;

        final FragmentManager fragmentManager = getFragmentManager();

        <strong>mBrowseFragment = (BrowseFragment) fragmentManager.findFragmentById(

                R.id.browse_fragment);</strong>

        ImageView iconView = (ImageView) rootView.findViewById(R.id.header_icon);

        Drawable icon = rootView.getResources().getDrawable(R.drawable.ic_action_video, null);

        iconView.setImageDrawable(icon);

        // Set display parameters for the BrowseFragment

        mBrowseFragment.setHeadersState(BrowseFragment.HEADERS_ENABLED);

        mBrowseFragment.setTitle(getString(R.string.app_name));

        mBrowseFragment.setBadgeDrawable(getResources().getDrawable(

                R.drawable.ic_launcher));

        mBrowseFragment.setBrowseParams(params);

        TextView label = (TextView) rootView.findViewById(R.id.header_label);

        label.setText(headerItem.getName());

    }

    @Override

    public void onUnbindViewHolder(ViewHolder viewHolder) {

    // no op

    }

}

</pre>

<p>This example shows how to define the presenter for a complex layout with

multiple views, and you could use this pattern to do something even more complex.

However, an easier way to combine a {@link android.widget.TextView} with a

drawable resource is to use the <a href="{@docRoot}reference/android/widget/TextView.html#attr_android:drawableLeft">

{@code TextView.drawableLeft}</a> attribute. Doing it this way, you don't need the

{@link android.widget.ImageView} shown here.</p>

<p>In the {@link android.support.v17.leanback.app.BrowseFragment} implementation that displays the

catalog browser, use the {@link android.support.v17.leanback.app.BrowseFragment#setHeaderPresenterSelector(android.support.v17.leanback.widget.PresenterSelector) setHeaderPresenterSelector()}

method to set the presenter for the row header, as shown in the following example.</p>

<pre>

setHeaderPresenterSelector(new PresenterSelector() {

    @Override

    public Presenter getPresenter(Object o) {

        return new IconHeaderItemPresenter();

    }

});

</pre>

<h2 id="lists">Displaying Media Lists</h2>

<h3 id="hide-heads">Hide or Disable Headers</h3>

<p>Sometimes you may not want the row headers to appear: when there aren't enough categories to

require a scrollable list, for example. Call the {@link android.support.v17.leanback.app.BrowseFragment#setHeadersState(int) BrowseFragment.setHeadersState()}

method during the fragment's {@link android.app.Fragment#onActivityCreated(android.os.Bundle) onActivityCreated()}

method to hide or disable the row headers. The {@link android.support.v17.leanback.app.BrowseFragment#setHeadersState(int) setHeadersState()}

method sets the initial state of the headers in the browse fragment given one of the following

constants as a parameter:</p>

<ul>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#HEADERS_ENABLED} - When the browse

  fragment activity is created, the headers are enabled and shown by default. The headers appear as

  shown in figures 1 and 2 on this page.</li>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#HEADERS_HIDDEN} - When the browse

  fragment activity is created, headers are enabled and hidden by default. The header section of the

  screen is collapsed, as shown in <a href="{@docRoot}training/tv/playback/card.html#collapsed">

  figure 1</a> of <a href="{@docRoot}training/tv/playback/card.html">Providing a Card View</a>. The

  user can select the collapsed header section to expand it.</li>

  <li>{@link android.support.v17.leanback.app.BrowseFragment#HEADERS_DISABLED} - When the browse

  fragment activity is created, headers are disabled by default and are never displayed.</li>

</ul>

<p>If either {@link android.support.v17.leanback.app.BrowseFragment#HEADERS_ENABLED} or

{@link android.support.v17.leanback.app.BrowseFragment#HEADERS_HIDDEN} is set, you can call

{@link android.support.v17.leanback.app.BrowseFragment#setHeadersTransitionOnBackEnabled(boolean) setHeadersTransitionOnBackEnabled()}

to support moving back to the row header from a selected content item in the row. This is enabled by

default (if you don't call the method), but if you want to handle the back movement yourself, you

should pass the value <code>false</code> to {@link android.support.v17.leanback.app.BrowseFragment#setHeadersTransitionOnBackEnabled(boolean) setHeadersTransitionOnBackEnabled()}

and implement your own back stack handling.</p>

<h2 id="lists">Display Media Lists</h2>

<p>

  The {@link android.support.v17.leanback.app.BrowseFragment} allows you to define and display

  browsable media content categories and media items from a media catalog using adapters and

  presenters. Adapters enable you to connect to local or online data sources that contain your

  media catalog information. Presenters hold data about media items and provide layout information

  for displaying an item on screen.

  The {@link android.support.v17.leanback.app.BrowseFragment} class allows you

  to define and display browsable media content categories and media items from

  a media catalog using adapters and presenters. Adapters enable you to connect

  to local or online data sources that contain your media catalog information.

  Adapters use presenters to create views and bind data to those views for

  displaying an item on screen.

</p>

<p>

</pre>

<p>

  Once you have constructed a presenter class for your media items, you can build and attach an

  adapter to the {@link android.support.v17.leanback.app.BrowseFragment} to display those items on

  screen for browsing by the user. The following example code demonstrates how to construct an

  adapter to display categories and items in those categories using the {@code StringPresenter}

  class shown in the previous code example:

  Once you have constructed a presenter class for your media items, you can build

  an adapter and attach it to the {@link android.support.v17.leanback.app.BrowseFragment}

  to display those items on screen for browsing by the user. The following example

  code demonstrates how to construct an adapter to display categories and items

  in those categories using the {@code StringPresenter} class shown in the

  previous code example:

</p>

<pre>

        listRowAdapter.add("Media Item 1");

        listRowAdapter.add("Media Item 2");

        listRowAdapter.add("Media Item 3");

        HeaderItem header = new HeaderItem(i, "Category " + i, null);

        HeaderItem header = new HeaderItem(i, "Category " + i);

        mRowsAdapter.add(new ListRow(header, listRowAdapter));

    }

  This example shows a static implementation of the adapters. A typical media browsing application

  uses data from an online database or web service. For an example of a browsing application that

  uses data retrieved from the web, see the

  <a href="http://github.com/googlesamples/androidtv-leanback">Android TV</a> sample app.

  <a href="http://github.com/googlesamples/androidtv-leanback">Android Leanback sample app</a>.

</p>

<h2 id="background">Update the Background</h2>

<p>

  In order to add visual interest to a media-browsing app on TV, you can update the background

  image as users browse through content. This technique can make interaction with your app feel

  more cinematic and enjoyable for users.

  image as users browse through content. This technique can make interaction with your app more

  cinematic and enjoyable.

</p>

<p>

        @Override

        public void onItemSelected(Object item, Row row) {

            if (item instanceof Movie ) {

                URI uri = ((Movie)item).getBackdropURI();

                updateBackground(uri);

                Drawable background = ((Movie)item).getBackdropDrawable();

                updateBackground(background);

            } else {

                clearBackground();

            }

Android Leanback sample app</a>, available on GitHub. Use this sample code to start your own

app.</p>

<img itemprop="image" src="{@docRoot}images/tv/app-browse.png" alt="App main screen"/>

<img itemprop="image" src="{@docRoot}images/tv/card-view.png" alt="App card view" id="collapsed"/>

<p class="img-caption"><b>Figure 1.</b> The <a href="https://github.com/googlesamples/androidtv-Leanback">

Leanback sample app</a> browse fragment with a card presenter displaying card view objects.</p>

Leanback sample app</a> image card view when selected.</p>

<h2 id="presenter">Create a Card Presenter</h2>

</pre>

<p>When the user selects the {@link android.support.v17.leanback.widget.ImageCardView}, it expands

to reveal its text area with the background color you specify, as shown in figure 2.</p>

to reveal its text area with the background color you specify, as shown in figure 1.</p>

<img itemprop="image" src="{@docRoot}images/tv/card-view.png" alt="App card view"/>

<p class="img-caption"><b>Figure 2.</b> The <a href="https://github.com/googlesamples/androidtv-Leanback">

Leanback sample app</a> image card view when selected.</p>