docs: add guide for optimizing tablet apps for handsets

          </a></li>

        </ul>

      </li>

      <li><a href="<?cs var:toroot ?>guide/practices/optimizing-for-3.0.html">

            <span class="en">Optimizing Apps for Android 3.0</span>

          </a></li>

      <li><a href="<?cs var:toroot ?>guide/practices/tablets-and-handsets.html">

            <span class="en">Supporting Tablets and Handsets</span>

          </a> <span class="new">new!</span></li>

      <li class="toggle-list">

        <div><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/index.html">

               <span class="en">UI Guidelines</span>

page.title=Optimizing Apps for Android 3.0

@jd:body

<div id="deprecatedSticker">

  <a href="#" 

     onclick="$('#naMessage').show();$('#deprecatedSticker').hide();return false">

    <strong>This doc is deprecated</strong></a>

</div>

<div id="naMessage" style="display:block">

<div><p><strong>This document has been deprecated.</strong></p>

 <p>To learn about how you can  optimize your app for both tablets and handsets, please

read the guide to <a href="tablets-and-handsets.html">Supporting Tablets and

Handsets</a>.</p>

 <input style="margin-top:1em;padding:5px" type="button"

        value="That's nice, but I still want to read this document"

onclick="$('#naMessage').hide();$('#deprecatedSticker').show()" />

</div>

</div>

<div id="qv-wrapper">

<div id="qv">

<h2>In this document</h2>

<h2>See also</h2>

<ol>

  <li><a href="tablets-and-handsets.html">Supporting Tablets

and Handsets</a></li>

  <li><a

href="{@docRoot}sdk/compatibility-library.html">Compatibility Library</a></li>

  <li><a href="http://code.google.com/p/iosched/">Google I/O App source code</a></li>

  <h2>In this document</h2>

  <ol>

    <li><a href="#FilteringHansetApps">Filtering a Handset Application from Tablets</a></li>

    <li><a href="#FilteringTabletApps">Filtering a Tablet Application from Handsets</a></li>

    <li><a href="#FilteringHansetApps">Declaring an App is Only for Handsets</a></li>

    <li><a href="#FilteringTabletApps">Declaring an App is Only for Tablets</a></li>

    <li><a href="#MultiApks">Publishing Multiple APKs for Different Screens</a></li>

  </ol>

<h2 id="FilteringHandsetApps">Filtering a Handset Application from Tablets</h2>

<h2 id="FilteringHandsetApps">Declaring an App is Only for Handsets</h2>

<p>Because the system generally scales applications to fit larger screens well, you shouldn't

need to filter your application from larger screens. As long as you follow the <a

<pre>

<manifest ... >

    ...

    <compatible-screens>

        <!-- all small size screens -->

        <screen android:screenSize="small" android:screenDensity="ldpi" />

        <screen android:screenSize="normal" android:screenDensity="hdpi" />

        <screen android:screenSize="normal" android:screenDensity="xhdpi" />

    </compatible-screens>

    ...

    <application ... >

        ...

    <application>

<h2 id="FilteringTabletApps">Filtering a Tablet Application from Handsets</h2>

<p>If your application's UI is adversely affected when the system scales your application down to

smaller screens, you should add <a

href="{@docRoot}guide/topics/resources/providing-resources.html#AlternativeResources">alternative

layouts</a> for smaller screens to adjust the layout for those screens. However, sometimes your

layout still might not fit a smaller screen or you've explicitly designed your application only for

tablets and other large devices. In this case, you can manage the availability of your application

to smaller screens by using the <a

<h2 id="FilteringTabletApps">Declaring an App is Only for Tablets</h2>

<p>If you don't want your app to be used on handsets (perhaps your app truly makes sense only on a

large screen) or you need time to optimize it for smaller screens, you can prevent small-screen

devices from downloading your app by using the <a

href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code

&lt;supports-screens>}</a> manifest element.</p>

<p>For example, if you want your application to be available only to large and extra large

screens, you can declare the element in your manifest like this:</p>

<p>For example, if you want your application to be available only to tablet devices, you can declare

the element in your manifest like this:</p>

<pre>

<manifest ... >

    ...

    <supports-screens android:smallScreens="false"

                      android:normalScreens="false"

                      android:largeScreens="true"

                      android:xlargeScreens="true" />

                      android:xlargeScreens="true"

                      android:requiresSmallestWidthDp="600" />

    ...

    <application ... >

        ...

    <application>

    </application>

</manifest>

</pre>

<p>External services such as Android Market read this manifest element and use it to ensure that

your application is available only to devices with either a large or an extra large screen.</p>

<p>This describes your app's screen-size support in two different ways:</p>

<ul>

  <li>It declares that the app does <em>not</em> support the screen sizes "small" and

"normal", which are traditionally not tablets.</li>

  <li>It declares that the app requires a screen size with a minimum usable area that is at least

600dp wide.</li>

</ul>

<p>The first technique is for devices that are running Android 3.1 or older, because those devices

declare their size based on generalized screen sizes. The <a

href="{@docRoot}guide/topics/manifest/supports-screens-element.html#requiresSmallest">{@code

requiresSmallestWidthDp}</a> attribute is for devices running Android 3.2 and newer, which includes

the capability for apps to specify size requirements based on a minimum number of

density-independent pixels available.  In this example, the app declares a minimum width requirement

of 600dp, which generally implies a 7"-or-greater screen. </p>

<p>Your size choice might be different, of course, based on how well your design works on different

screen sizes; for example, if your design works well only on screens that are 9" or larger, you

might require a minimum width of 720dp.</p>

<p>The catch is that you must compile your application against Android 3.2 or higher in order to use

the <code>requiresSmallestWidthDp</code> attribute. Older versions don't understand this attribute

and will raise a compile-time error. The safest thing to do is develop your app against the platform

that matches the API level you've set for <a

href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">minSdkVersion</a

>. When you're making final preparations to build your release candidate, change the build target to

Android 3.2 and add the <code>requiresSmallestWidthDp</code> attribute. Android versions older than

3.2 simply ignore that XML attribute, so there's no risk of a runtime failure.</p>

<p>For more information about why the "smallest width" screen size is

important for supporting different screen sizes, read <a

href="http://android-developers.blogspot.com/2011/07/new-tools-for-managing-screen-sizes.html">New

Tools for Managing Screen Sizes</a>.</p>

<p class="caution"><strong>Caution:</strong> If you use the <a

href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code

to prevent your application from being downloaded on larger screens, use <a

href="{@docRoot}guide/topics/manifest/compatible-screens-element.html">{@code

&lt;compatible-screens>}</a>, as discussed in the previous section about <a

href="#FilteringHandsetApps">Filtering a Handset Application from Tablets</a>.</p>

href="#FilteringHandsetApps">Declaring an App is Only for Handsets</a>.</p>

<p>Remember, you should strive to make your application available to as many devices as possible by

applying all necessary techniques for <a

  <h2>See also</h2>

  <ol>

    <li><a

href="http://android-developers.blogspot.com/2011/09/thinking-like-web-designer.html">Thinking

Like a Web Designer</a></li>

    <li><a

href="{@docRoot}guide/topics/resources/providing-resources.html#AlternativeResources">

Providing Alternative Resources</a></li>

    <li><a href="{@docRoot}guide/practices/ui_guidelines/icon_design.html">Icon Design