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* changes:
  docs only. expand the uses-feature docs
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Android (Google) Code Review
2009-09-01 19:04:15 -07:00
parent 4e60d012c9 c6747d02c6
commit dc5164134c
1 changed files with 61 additions and 7 deletions
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68
docs/html/guide/topics/manifest/uses-feature-element.jd
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@@ -15,20 +15,60 @@ page.title=<uses-feature>
<dd><code><a href="{@docRoot}guide/topics/manifest/manifest-element.html">&lt;manifest&gt;</a></code></dd>
<dt>description:</dt>
<dd>This element specifies a specific feature used by the application.
<dd>This element declares a specific feature used by the application.
Android provides some features that may not be equally supported by all
Android devices. In a manner similar to the <code><a href="uses-sdk-element.html">&lt;uses-sdk></a></code>
element, this element allows an application to specify which potentially variable
features it requires. In this way, the application
will not be installed on devices that do not offer the required feature.</p>
element, this element allows an application to specify which device-variable
features it uses. In this way, the application
will not be installed on devices that do not offer the feature.</p>
<p>For example, an application might specify that it requires a certain version of Open GL.
If a device does not support that version of Open GL, then it will not allow installation of the application.</p>
<p>For example, an application might specify that it requires a camera with auto-focus capabilities.
If a device does not provide a camera with auto-focus, then it will not allow
installation of the application.</p>
<p>In order to maintain strict device compatibility, it's very important that you use
this element to declare all features that your application uses. Failure to declare
a feature may result your application being installed on a device
that does not support the feature and your application failing.</p>
<p>For some features, there may exist a specfic attribute that allows you to define
a version of the feature, such as the version of Open GL used (declared with
<a href="#glEsVersion">{@code glEsVersion}</a>). Other features that either do or do not
exist for a device, such as camera auto-focus, are declared using the
<a href="#name">{@code name}</a> attribute.</p>
<p>Any software or hardware features that may vary among Android-powered
devices will be listed on this page among the attributes below. If you see any features
here that you use in your application, you should include a {@code
&lt;uses-feature>} element for each one. For example, if your application uses the device
camera, then you should include the following in your {@code AndroidManifest.xml}:</p>
<pre>
&lt;uses-feature android:name="android.hardware.camera" />
</pre>
<p>If you declare "android.hardware.camera", then your application is considered
compatible with all devices that include a camera, regardless of whether auto-focus is
available or not. If you also use the auto-focus features (available through the {@link
android.hardware.Camera Camera API}), then you need to include an additional
{@code &lt;uses-feature>} element that declares the "android.hardware.camera.autofocus"
feature. Also note that you must still request the {@link android.Manifest.permission#CAMERA
CAMERA permission}. Requesting permission grants your application access to the
appropriate hardware and software, while declaring the features used by
your application ensures proper device compatibility.</p>
<p>Although the {@code &lt;uses-feature>} element is only activated for devices running
API Level 4 or higher, it is safe to include this for applications that declare
a <a href="uses-sdk-element.html#min">{@code minSdkVersion}</a>
of "3" or lower. Devices running older versions of the platform
will simply ignore this element, but newer devices will recognize it and enforce
installation restrictions based on whether the device supports the feature.</p>
<p class="note"><strong>Note:</strong>
For each feature required by your application, you must include a new {@code
&lt;uses-feature>} element. Multiple features cannot be declared in one
instance of this element.</p>
</dd>
@@ -51,16 +91,30 @@ instance of this element.</p>
<table>
<tr>
<th>Feature</th>
<th>Value</th>
<th>Description</th>
</tr><tr>
<td rowspan="3">Camera</td>
<td>"{@code android.hardware.camera}"</td>
<td>The application requires a camera.</td>
</tr><tr>
<td>"{@code android.hardware.camera.autofocus}"</td>
<td>The application requires a camera with auto-focus capability.
As a prerequisite, "{@code android.hardware.camera}" must also be declared
with a separate {@code &lt;uses-feature>} element.</td>
with a separate {@code &lt;uses-feature>} element.
</td>
<tr>
<td colspan="2">
<strong>Note:</strong> Any application that requests the
{@link android.Manifest.permission#CAMERA CAMERA permission} but does <em>not</em>
declare any camera features with the {@code &lt;uses-feature>} element will be assumed
to use all camera features (such as auto-focus). Thus, the application will not
be compatible with devices that do not support all features. Please use
{@code &lt;uses-feature>} to declare only the camera features that your
application needs.
</td>
</tr>
</tr>
</table>