android_frameworks_base/docs/html/preview/tv/games/index.jd

ikpage.title=Games on TV
page.tags="controller"

@jd:body

<div id="qv-wrapper">
<div id="qv">
  <h2>In this document</h2>
  <ol>
    <li><a href="#display">Display</li></a></li>
    <li><a href="#control">Input Devices</li></a></li>
    <li><a href="#manifest">Manifest</li></a></li>
    <li><a href="#gpgs">Google Play Game Services</li></a></li>
    <li><a href="#web">Web</a></li>
  </ol>
</div>
</div>

<p>The television screen presents a number of considerations that may be new to mobile-game
developers. These areas include its large size, its control scheme, and the fact that all
players are viewing it simultaneously.</p>


<h2 id=display>Display</h2>
<p>The two main things to keep in mind when developing games for the TV screen are its nature as a
shared display and the need to design your game for a landscape orientation.</p>
<h3>Shared display</h3>
<p>A living-room TV poses design challenges for multiplayer games, in that all players can see
everything. This issue is especially relevant to games (such as card games or strategy games) that
rely on each player’s possession of hidden information.</p>
<p>Some mechanisms you can implement to address the problem of one player’s eavesdropping
on another’s information are:</p>
<ul>
<li>A blinder on the screen to help conceal information. For example, in a
turn-based game like a word or card game, one player at a time might view the display. When the
player finishes a move, the game allows him or her to cover the screen with a blinder that
blocks anyone from viewing secret information. When the next player begins a turn, the blinder
opens to reveal his or her own information.</li>
<li>A companion app, running on a phone or tablet, can enable a player to conceal
information.</li>
</ul>
<h3>Landscape display</h3>
<p>A TV is always sideways: You can’t turn it, and there is no
portrait orientation. Always design your TV games to be displayed in landscape
mode.</p>

<h2 id="control">Input Devices</h2>
<p>TVs don't have touch interfaces, so it's even more important to get your controls right and make
 sure that players find them intuitive and fun to use. The separation of controller from device also
introduces some other issues to pay attention to, like keeping track of multiple players'
controllers, and handling disconnects gracefully.</p>
<h3>D-pad</h3>
<p>Plan your control scheme around a directional pad (D-pad) control, since this control set is the
default for Android TV devices. The player needs to be able to use a D-Pad in all aspects of the
game&ndash;not just controlling core
gameplay, but also navigating menus and ads. For this reason, you should also ensure that your
Android TV game does not refer to a touch interface: for example, an Android TV game cannot tell a
player to <strong>Tap to skip</strong>.</p>
<p>How you shape the player's interaction with the controller can be key to achieving a great user
experience:
  <ul>
  <p><li><strong>Communicate Controller Requirements up Front</strong> - Use your Play Store description to communicate to the player any expectations about
controllers. If a game is better suited to a gamepad with a joystick than one with only a D-pad,
make this fact clear. A player who uses an ill-suited controller for a game is likely to have a
subpar experience&ndash;and penalize your game in the ratings.</p>
  <p><li><strong>Use Consistent Button Mapping</strong> - Intuitive and flexible button mapping is key to a good user experience. For example,
you can adhere to accepted custom by using the A button to <code>Accept</code>, and the B button to
<code>Cancel</code>. You can also offer flexibility in the form of remappability. For more
information on button mapping, see <a
href="http://developer.android.com/training/game-controllers/controller-input.html">Handling
Controller Actions</a>.</p>
  <p><li><strong>Detect Controller Capabilities and Adjust Accordingly</strong> - Query the controller about its capabilities in order to optimize the match between
controller and game. For example, you may intend for a player to steer an object by waving the
controller in the air. If a player's controller lacks accelerometer and gyroscope hardware, however,
waving will not work. When, however, your game queries the controller and discovers that motion detection
is not supported, it can switch over to an alternative, available control scheme.
For more information on querying controller capabilities, see <a
href="http://developer.android.com/training/game-controllers/compatibility.html">Supporting
Controllers Across Android Versions</a>.</p>
  </ul>
<h3>Back-button behavior</h3>
<p>The Back button should never act as a toggle. For example, do not use it to both open and close
a menu. It should only navigate backward, breadcrumb-style, through the previous screens the player has
been on. For example: Game play &gt; Game pause screen &gt; Game
main screen &gt; Android home screen.</p>
<p>Since the Back button should only perform linear (backward) navigation, you may use the
back button to leave an in-game menu (opened by a different button) and return to gameplay. For
more information about design for navigation, see <a
href="http://developer.android.com/design/patterns/navigation.html">Navigation with Back and
Up</a>. To learn about implementation, refer to <a
href="http://developer.android.com/training/implementing-navigation/temporal.html">Providing Proper
Back Navigation</a>. </p>
<h3>Handling multiple controllers</h3>
<p>When multiple players are playing a game, each with his or her own controller, it is important
to map each player-controller pair. For information on how to implement controller-number
identification, see <a href="http://developer.android.com/reference/android/view/InputDevice.html
#getControllerNumber(">Input Devices</a>) on the Android developer site.</p>
<h3>Handling disconnects</h3>
<p>When a controller is disconnected in the middle of gameplay, the game should pause, and a dialog
should appear prompting the disconnected player to reconnect his or her controller.</p>
<p>The dialog should also offer troubleshooting tips (for example, a pop-up dialog telling the player to
"Check your Bluetooth connection"). For more information on implementing input-device support, see <a
href="http://developer.android.com/training/game-controllers/controller-input.html">Supporting Game
Controllers"</a>. Specific information about Bluetooth connections is at <a
href="http://developer.android.com/guide/topics/connectivity/bluetooth.html">Bluetooth</a>.</p>

<h2 id="manifest">Manifest</h2>
<p>Games are displayed in a separate row from regular apps in the launcher. Android TV uses the
<code>android:isGame</code> flag to differentiate games from non-game apps. You can assign it a
value of either <code>true</code> or <code>false</code>. For example:</p>
<pre class="fragment">&lt;application&gt;
 ...
&lt; android:isGame=["true" | "false"] &gt;
 ...
&lt;/application&gt;</pre>

<h2 id="gpgs">Google Play Game Services</h2>
<p>If your game integrates Google Play Game Services, you should keep in mind a number of
considerations pertaining to achievements, sign-on, saving games, and multiplayer play.</p>
<h3>Achievements</h3>
<p>Your game should include at least five (earnable) achievements. Only a user controlling gameplay
from a supported input device should be able to earn achievements. For more information on
Achievements and how to implement them, see <a
href="https://developers.google.com/games/services/android/achievements">Achievements in
Android</a>.</p>
<h3>Sign-in</h3>
<p>Your game should attempt to sign the user in on launch. If the player declines sign-in several
times in a row, your game should stop asking. Learn more about sign-in at <a
href="https://developers.google.com/games/services/training/signin">Implementing Sign-in on
Android</a>.</p>
<h3>Saving</h3>
<p>We highly recommend using Play Services <a
href="https://developers.google.com/games/services/common/concepts/cloudsave">Cloud Save</a> to
store your game save. Your game should bind game saves to a specific Google account, so as to be
uniquely identifiable even across devices: Whether the player is using a handset or a TV, the game
should be able to pull the same game-save information from his or her account.</p>
<p>You should also provide an option in your game's UI to allow the player to delete locally and
cloud-stored data. You might put the option in the game's <code>Settings</code> screen. For
specifics on implementing Cloud Save, see <a
href="https://developers.google.com/games/services/android/cloudsave">Cloud Save in Android</a>.</p>
<h3>Multiplayer experience</h3>
<p>A game offering a multiplayer experience must allow at least two players to enter a room. For
further information on multiplayer games in Android, see the <a
href="https://developers.google.com/games/services/android/realtimeMultiplayer">Real-time
Multiplayer</a> and <a href="">Turn-based Multiplayer</a> documentation on the Android developer
site.</p>

<h2 id="web">Web</h2>
<p>We discourage including web browsing in games for Android TV. The television set is not well-suited for browsing, either in terms of display or control scheme.</p>
<p class="note"><strong>Note:</strong> You can use the {@link android.webkit.WebView} class for logins to services like Google+ and
Facebook. </p>