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diff --git a/docs/html/guide/practices/screens-distribution.jd b/docs/html/guide/practices/screens-distribution.jd new file mode 100644 index 0000000..0c5193b --- /dev/null +++ b/docs/html/guide/practices/screens-distribution.jd @@ -0,0 +1,164 @@ +page.title=Distributing to Specific Screens +parent.title=Supporting Multiple Screens +parent.link=screens_support.html + +@jd:body + +<div id="qv-wrapper"> +<div id="qv"> + + <h2>Quickview</h2> + <ul> + <li>If necessary, you can control distribution of your application based on the device +screen configuration</li> + </ul> + + <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> + </ol> + + <h2>See also</h2> + <ol> + <li><a +href="{@docRoot}guide/practices/screens_support.html">Supporting Multiple Screens</a></li> + <li><a +href="{@docRoot}guide/practices/optimizing-for-3.0.html">Optimizing Apps for Android 3.0</a></li> + </ol> + +</div> +</div> + + + +<p>Although we recommend that you design your application to function properly on multiple +configurations of screen size and density, you can instead choose to limit the distribution of your +application to certain types of screens, such as only tablets and other large devices or only +handsets and similar-sized devices. To do so, you can enable filtering by external services such as +Android Market by adding elements to your manifest file that specify the screen configurations your +application supports.</p> + +<p>However, before you decide to restrict your application to certain screen configurations, you +should understand the techniques for <a +href="{@docRoot}guide/practices/screens_support.html">supporting multiple screens</a> and implement +them to the best of your ability. By supporting multiple screens, your application can be made +available to the greatest number of users with different devices, using a single {@code .apk}.</p> + + + +<h2 id="FilteringHandsetApps">Filtering a Handset Application from Tablets</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 +href="{@docRoot}guide/practices/screens_support.html#screen-independence">Best Practices for Screen +Independence</a>, your application should work well on larger screens such as tablets. However, you +might discover that your application can't scale up well or perhaps you've decided to publish two +versions of your application for different screen configurations. In such a case, you can use the <a +href="{@docRoot}guide/topics/manifest/compatible-screens-element.html">{@code +<compatible-screens>}</a> element to manage the distribution of your application based on +combinations of screen size and density. External services such as Android Market use this +information to apply filtering to your application, so that only devices that have a screen +configuration with which you declare compatibility can download your application.</p> + +<p>The <a href="{@docRoot}guide/topics/manifest/compatible-screens-element.html">{@code +<compatible-screens>}</a> element must contain one or more {@code <screen>} elements. Each +{@code <screen>} element specifies a screen configuration with which your application is +compatible, using both the {@code android:screenSize} and {@code android:screenDensity} attributes. +Each {@code <screen>} element <strong>must include both attributes</strong> to specify an +individual screen configuration—if either attribute is missing, then the element is invalid +(external services such as Android Market will ignore it).</p> + +<p>For example, if your application is compatible with only small and normal size screens, +regardless of screen density, you must specify eight different {@code <screen>} elements, +because each screen size has four density configurations. You must declare each one of +these; any combination of size and density that you do <em>not</em> specify is considered a screen +configuration with which your application is <em>not</em> compatible. Here's what the manifest +entry looks like if your application is compatible with only small and normal screen sizes:</p> + +<pre> +<manifest ... > + ... + <compatible-screens> + <!-- all small size screens --> + <screen android:screenSize="small" android:screenDensity="ldpi" /> + <screen android:screenSize="small" android:screenDensity="mdpi" /> + <screen android:screenSize="small" android:screenDensity="hdpi" /> + <screen android:screenSize="small" android:screenDensity="xhdpi" /> + <!-- all normal size screens --> + <screen android:screenSize="normal" android:screenDensity="ldpi" /> + <screen android:screenSize="normal" android:screenDensity="mdpi" /> + <screen android:screenSize="normal" android:screenDensity="hdpi" /> + <screen android:screenSize="normal" android:screenDensity="xhdpi" /> + </compatible-screens> + <application ... > + ... + <application> +</manifest> +</pre> + +<p class="note"><strong>Note:</strong> Although you can also use the <a +href="{@docRoot}guide/topics/manifest/compatible-screens-element.html">{@code +<compatible-screens>}</a> element for the reverse scenario (when your application is not +compatible with smaller screens), it's easier if you instead use the <a +href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code +<supports-screens>}</a> as discussed in the next section, because it doesn't require you +to specify each screen density your application supports.</p> + + + +<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 +href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code +<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> + +<pre> +<manifest ... > + ... + <supports-screens android:smallScreens="false" + android:normalScreens="false" + android:largeScreens="true" + android:xlargeScreens="true" /> + <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 class="caution"><strong>Caution:</strong> If you use the <a +href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code +<supports-screens>}</a> element for the reverse scenario (when your application is not compatible +with <em>larger</em> screens) and set the larger screen size attributes to {@code "false"}, then +external services such as Android Market <strong>do not</strong> apply filtering. Your application +will still be available to larger screens, but when it runs, it will not resize to fit the screen. +Instead, the system will draw it in a "postage stamp" window that's the same relative size as the +screen size that your application does support (see <a +href="screens-support-1.5.html#CompatMode">compatibility mode</a> for more information). If you want +to prevent your application from being downloaded on larger screens, use <a +href="{@docRoot}guide/topics/manifest/compatible-screens-element.html">{@code +<compatible-screens>}</a>, as discussed in the previous section about <a +href="#FilteringHandsetApps">Filtering a Handset Application from Tablets</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 +href="{@docRoot}guide/practices/screens_support.html">supporting multiple screens</a>. You should +use <a href="{@docRoot}guide/topics/manifest/compatible-screens-element.html">{@code +<compatible-screens>}</a> or <a +href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code +<supports-screens>}</a> only when you cannot provide compatibility on all screen configurations +or you have decided to provide different versions of your application for different sets of screen +configurations.</p> + |