huali_tcs
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android_core
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  <div class="section" id="getting-started">
<span id="id1"></span><h1>Getting started<a class="headerlink" href="#getting-started" title="Permalink to this headline">¶</a></h1>
<p>Before diving into ROS enabled Android application development, you should be
familiar with <em class="xref std std-ref">rosjava</em> and <a class="reference external" href="http://developer.android.com/training/index.html">Android
application development</a> in general.</p>
<div class="section" id="creating-a-new-android-application">
<h2>Creating a new Android application<a class="headerlink" href="#creating-a-new-android-application" title="Permalink to this headline">¶</a></h2>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">This is still a work in progress. There are many obvious limitations
and the process will be improved in the near future.</p>
</div>
<p>Currently, the easiest way to create a new application is to create your own
package in the android_core stack by copying one of the tutorial packages (e.g.
android_tutorial_pubsub).</p>
<div class="highlight-bash"><div class="highlight"><pre>roscd android_core
cp -a android_tutorial_pubsub my_package
</pre></div>
</div>
<p>After that, modify android_core/settings.gradle to include your new package.</p>
<div class="highlight-bash"><div class="highlight"><pre>rosed android_core/settings.gradle
./gradlew my_package:clean my_package:debug
</pre></div>
</div>
<p>At this point, you may interact with your Android projects as described in the
<a class="reference external" href="http://developer.android.com/guide/developing/building/building-cmdline.html">Android documentation</a>. Please start there if the following quick start
instructions are insufficient for you.</p>
<p>Use <a class="reference external" href="http://ant.apache.org/">Apache Ant</a> to install your new Android application:</p>
<div class="highlight-bash"><div class="highlight"><pre>roscd my_package
ant installd
</pre></div>
</div>
<p>You can also use ant to build the application. However, if you add, remove, or
modify a dependency in the build.gradle file, you will need to execute the
<a class="reference external" href="http://gradle.org/docs/current/userguide/gradle_wrapper.html">gradle wrapper</a> as described above in order to update the Android
application&#8217;s external dependencies (located in the <tt class="docutils literal"><span class="pre">my_package/libs</span></tt>
directory).</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">You may also build and run your application from Eclipse. For more
information, see <a class="reference internal" href="building.html"><em>Building android_core</em></a>.</p>
</div>
</div>
<div class="section" id="using-rosactivity">
<span id="life-of-a-rosactivity"></span><h2>Using RosActivity<a class="headerlink" href="#using-rosactivity" title="Permalink to this headline">¶</a></h2>
<p>The <a class="reference external" href="javadoc/org/ros/android/RosActivity.html#">RosActivity</a> class is the base class for all of
your ROS enabled Android applications. Let&#8217;s consider the following example
from the android_tutorial_pubsub package. In this example, we create a
<a class="reference external" href="javadoc/org/ros/node/topic/Publisher.html#">Publisher</a> and a
<a class="reference external" href="javadoc/org/ros/node/topic/Subscriber.html#">Subscriber</a> that will exchange &#8220;Hello, World&#8221;
messages.</p>
<div class="highlight-java"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre> 1
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53</pre></div></td><td class="code"><div class="highlight"><pre><span class="kn">package</span> <span class="n">org</span><span class="o">.</span><span class="na">ros</span><span class="o">.</span><span class="na">android</span><span class="o">.</span><span class="na">android_tutorial_pubsub</span><span class="o">;</span>

<span class="kn">import</span> <span class="nn">android.os.Bundle</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.android.MessageCallable</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.android.RosActivity</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.android.view.RosTextView</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.node.NodeConfiguration</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.node.NodeMainExecutor</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.rosjava_tutorial_pubsub.Talker</span><span class="o">;</span>

<span class="cm">/**</span>
<span class="cm"> * @author damonkohler@google.com (Damon Kohler)</span>
<span class="cm"> */</span>
<span class="hll"><span class="kd">public</span> <span class="kd">class</span> <span class="nc">MainActivity</span> <span class="kd">extends</span> <span class="n">RosActivity</span> <span class="o">{</span>
</span>
  <span class="kd">private</span> <span class="n">RosTextView</span><span class="o">&lt;</span><span class="n">std_msgs</span><span class="o">.</span><span class="na">String</span><span class="o">&gt;</span> <span class="n">rosTextView</span><span class="o">;</span>
  <span class="kd">private</span> <span class="n">Talker</span> <span class="n">talker</span><span class="o">;</span>

  <span class="kd">public</span> <span class="nf">MainActivity</span><span class="o">()</span> <span class="o">{</span>
    <span class="c1">// The RosActivity constructor configures the notification title and ticker</span>
    <span class="c1">// messages.</span>
<span class="hll">    <span class="kd">super</span><span class="o">(</span><span class="s">&quot;Pubsub Tutorial&quot;</span><span class="o">,</span> <span class="s">&quot;Pubsub Tutorial&quot;</span><span class="o">);</span>
</span>  <span class="o">}</span>

  <span class="nd">@SuppressWarnings</span><span class="o">(</span><span class="s">&quot;unchecked&quot;</span><span class="o">)</span>
  <span class="nd">@Override</span>
  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">onCreate</span><span class="o">(</span><span class="n">Bundle</span> <span class="n">savedInstanceState</span><span class="o">)</span> <span class="o">{</span>
<span class="hll">    <span class="kd">super</span><span class="o">.</span><span class="na">onCreate</span><span class="o">(</span><span class="n">savedInstanceState</span><span class="o">);</span>
</span><span class="hll">    <span class="n">setContentView</span><span class="o">(</span><span class="n">R</span><span class="o">.</span><span class="na">layout</span><span class="o">.</span><span class="na">main</span><span class="o">);</span>
</span><span class="hll">    <span class="n">rosTextView</span> <span class="o">=</span> <span class="o">(</span><span class="n">RosTextView</span><span class="o">&lt;</span><span class="n">std_msgs</span><span class="o">.</span><span class="na">String</span><span class="o">&gt;)</span> <span class="n">findViewById</span><span class="o">(</span><span class="n">R</span><span class="o">.</span><span class="na">id</span><span class="o">.</span><span class="na">text</span><span class="o">);</span>
</span>    <span class="n">rosTextView</span><span class="o">.</span><span class="na">setTopicName</span><span class="o">(</span><span class="s">&quot;chatter&quot;</span><span class="o">);</span>
    <span class="n">rosTextView</span><span class="o">.</span><span class="na">setMessageType</span><span class="o">(</span><span class="n">std_msgs</span><span class="o">.</span><span class="na">String</span><span class="o">.</span><span class="na">_TYPE</span><span class="o">);</span>
    <span class="n">rosTextView</span><span class="o">.</span><span class="na">setMessageToStringCallable</span><span class="o">(</span><span class="k">new</span> <span class="n">MessageCallable</span><span class="o">&lt;</span><span class="n">String</span><span class="o">,</span> <span class="n">std_msgs</span><span class="o">.</span><span class="na">String</span><span class="o">&gt;()</span> <span class="o">{</span>
      <span class="nd">@Override</span>
      <span class="kd">public</span> <span class="n">String</span> <span class="nf">call</span><span class="o">(</span><span class="n">std_msgs</span><span class="o">.</span><span class="na">String</span> <span class="n">message</span><span class="o">)</span> <span class="o">{</span>
        <span class="k">return</span> <span class="n">message</span><span class="o">.</span><span class="na">getData</span><span class="o">();</span>
      <span class="o">}</span>
    <span class="o">});</span>
  <span class="o">}</span>

  <span class="nd">@Override</span>
<span class="hll">  <span class="kd">protected</span> <span class="kt">void</span> <span class="nf">init</span><span class="o">(</span><span class="n">NodeMainExecutor</span> <span class="n">nodeMainExecutor</span><span class="o">)</span> <span class="o">{</span>
</span>    <span class="n">talker</span> <span class="o">=</span> <span class="k">new</span> <span class="n">Talker</span><span class="o">();</span>
    <span class="n">NodeConfiguration</span> <span class="n">nodeConfiguration</span> <span class="o">=</span> <span class="n">NodeConfiguration</span><span class="o">.</span><span class="na">newPrivate</span><span class="o">();</span>
    <span class="c1">// At this point, the user has already been prompted to either enter the URI</span>
    <span class="c1">// of a master to use or to start a master locally.</span>
    <span class="n">nodeConfiguration</span><span class="o">.</span><span class="na">setMasterUri</span><span class="o">(</span><span class="n">getMasterUri</span><span class="o">());</span>
    <span class="n">nodeMainExecutor</span><span class="o">.</span><span class="na">execute</span><span class="o">(</span><span class="n">talker</span><span class="o">,</span> <span class="n">nodeConfiguration</span><span class="o">);</span>
    <span class="c1">// The RosTextView is also a NodeMain that must be executed in order to</span>
    <span class="c1">// start displaying incoming messages.</span>
    <span class="n">nodeMainExecutor</span><span class="o">.</span><span class="na">execute</span><span class="o">(</span><span class="n">rosTextView</span><span class="o">,</span> <span class="n">nodeConfiguration</span><span class="o">);</span>
  <span class="o">}</span>
<span class="o">}</span>
</pre></div>
</td></tr></table></div>
<p>On line 14, we extend <a class="reference external" href="javadoc/org/ros/android/RosActivity.html#">RosActivity</a>.  When our
<a class="reference external" href="http://developer.android.com/reference/android/app/Activity.html">activity</a> starts, the <a class="reference external" href="javadoc/org/ros/android/RosActivity.html#">RosActivity</a> super class will:</p>
<ul class="simple">
<li>start the <a class="reference external" href="javadoc/org/ros/android/NodeMainExecutorService.html#">NodeMainExecutorService</a> as a <a class="reference external" href="http://developer.android.com/reference/android/app/Service.html">service</a>
in the <a class="reference external" href="http://developer.android.com/reference/android/app/Service.html#startForeground(int,android.app.Notification)">foreground</a>,</li>
<li>launch the <a class="reference external" href="javadoc/org/ros/android/MasterChooser.html#">MasterChooser</a> activity to prompt the
user to configure a master URI,</li>
<li>and display an ongoing <a class="reference external" href="http://developer.android.com/reference/android/app/Notification.html">notification</a> informing the user that ROS nodes are
running in the background.</li>
</ul>
<p>On line 22 we call the super constructor with two strings that become the title
and ticker message of an Android <a class="reference external" href="http://developer.android.com/reference/android/app/Notification.html">notification</a>. The user may tap on the
notification to shut down all ROS nodes associated with the application.</p>
<p>Lines 28-30 should look familiar to Android developers. We load the <a class="reference external" href="http://developer.android.com/reference/android/app/Activity.html">activity</a>
layout and get a reference to our
<a class="reference external" href="javadoc/org/ros/android/view/RosTextView.html#">RosTextView</a> (more on that later).</p>
<p>On line 42 we define the abstract method
<a class="reference external" href="javadoc/org/ros/android/RosActivity.html#init(org.ros.node.NodeMainExecutor)">RosActivity.init</a>.
This is where we kick off our <a class="reference external" href="javadoc/org/ros/node/NodeMain.html#">NodeMain</a>s and other
business logic.</p>
<p>And that&#8217;s it. <a class="reference external" href="javadoc/org/ros/android/RosActivity.html#">RosActivity</a> handles the rest of the
application&#8217;s lifecycle management including:</p>
<ul class="simple">
<li>acquiring and releasing <a class="reference external" href="http://developer.android.com/reference/android/os/PowerManager.WakeLock.html">WakeLocks</a> and <a class="reference external" href="http://developer.android.com/reference/android/net/wifi/WifiManager.WifiLock.html">WifiLocks</a>,</li>
<li>binding and unbinding the <a class="reference external" href="javadoc/org/ros/android/NodeMainExecutorService.html#">NodeMainExecutorService</a>,</li>
<li>and shutting down <a class="reference external" href="javadoc/org/ros/node/NodeMain.html#">NodeMain</a>s when the application exits.</li>
</ul>
</div>
<div class="section" id="nodes-and-views">
<h2>Nodes and Views<a class="headerlink" href="#nodes-and-views" title="Permalink to this headline">¶</a></h2>
<p>The android_core stack provides a number of Android <a class="reference external" href="http://developer.android.com/reference/android/view/View.html">Views</a> which implement
<a class="reference external" href="javadoc/org/ros/node/NodeMain.html#">NodeMain</a>. For example, let&#8217;s look at the implementation
of <a class="reference external" href="javadoc/org/ros/android/view/RosTextView.html#">RosTextView</a>. The intent of this view is
to display the textual representation of published messages.</p>
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76</pre></div></td><td class="code"><div class="highlight"><pre><span class="kn">package</span> <span class="n">org</span><span class="o">.</span><span class="na">ros</span><span class="o">.</span><span class="na">android</span><span class="o">.</span><span class="na">view</span><span class="o">;</span>

<span class="kn">import</span> <span class="nn">android.content.Context</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">android.util.AttributeSet</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">android.widget.TextView</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.android.MessageCallable</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.message.MessageListener</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.namespace.GraphName</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.node.ConnectedNode</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.node.Node</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.node.NodeMain</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.ros.node.topic.Subscriber</span><span class="o">;</span>

<span class="cm">/**</span>
<span class="cm"> * @author damonkohler@google.com (Damon Kohler)</span>
<span class="cm"> */</span>
<span class="kd">public</span> <span class="kd">class</span> <span class="nc">RosTextView</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="kd">extends</span> <span class="n">TextView</span> <span class="kd">implements</span> <span class="n">NodeMain</span> <span class="o">{</span>

  <span class="kd">private</span> <span class="n">String</span> <span class="n">topicName</span><span class="o">;</span>
  <span class="kd">private</span> <span class="n">String</span> <span class="n">messageType</span><span class="o">;</span>

  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setTopicName</span><span class="o">(</span><span class="n">String</span> <span class="n">topicName</span><span class="o">)</span> <span class="o">{</span>
    <span class="k">this</span><span class="o">.</span><span class="na">topicName</span> <span class="o">=</span> <span class="n">topicName</span><span class="o">;</span>
  <span class="o">}</span>

  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setMessageType</span><span class="o">(</span><span class="n">String</span> <span class="n">messageType</span><span class="o">)</span> <span class="o">{</span>
    <span class="k">this</span><span class="o">.</span><span class="na">messageType</span> <span class="o">=</span> <span class="n">messageType</span><span class="o">;</span>
  <span class="o">}</span>

  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setMessageToStringCallable</span><span class="o">(</span><span class="n">MessageCallable</span><span class="o">&lt;</span><span class="n">String</span><span class="o">,</span> <span class="n">T</span><span class="o">&gt;</span> <span class="n">callable</span><span class="o">)</span> <span class="o">{</span>
    <span class="k">this</span><span class="o">.</span><span class="na">callable</span> <span class="o">=</span> <span class="n">callable</span><span class="o">;</span>
  <span class="o">}</span>

  <span class="nd">@Override</span>
  <span class="kd">public</span> <span class="n">GraphName</span> <span class="nf">getDefaultNodeName</span><span class="o">()</span> <span class="o">{</span>
    <span class="k">return</span> <span class="k">new</span> <span class="nf">GraphName</span><span class="o">(</span><span class="s">&quot;android_gingerbread/ros_text_view&quot;</span><span class="o">);</span>
  <span class="o">}</span>

  <span class="nd">@Override</span>
<span class="hll">  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">onStart</span><span class="o">(</span><span class="n">ConnectedNode</span> <span class="n">connectedNode</span><span class="o">)</span> <span class="o">{</span>
</span>    <span class="n">Subscriber</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span> <span class="n">subscriber</span> <span class="o">=</span> <span class="n">connectedNode</span><span class="o">.</span><span class="na">newSubscriber</span><span class="o">(</span><span class="n">topicName</span><span class="o">,</span> <span class="n">messageType</span><span class="o">);</span>
    <span class="n">subscriber</span><span class="o">.</span><span class="na">addMessageListener</span><span class="o">(</span><span class="k">new</span> <span class="n">MessageListener</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;()</span> <span class="o">{</span>
      <span class="nd">@Override</span>
      <span class="kd">public</span> <span class="kt">void</span> <span class="nf">onNewMessage</span><span class="o">(</span><span class="kd">final</span> <span class="n">T</span> <span class="n">message</span><span class="o">)</span> <span class="o">{</span>
        <span class="k">if</span> <span class="o">(</span><span class="n">callable</span> <span class="o">!=</span> <span class="kc">null</span><span class="o">)</span> <span class="o">{</span>
          <span class="n">post</span><span class="o">(</span><span class="k">new</span> <span class="n">Runnable</span><span class="o">()</span> <span class="o">{</span>
            <span class="nd">@Override</span>
            <span class="kd">public</span> <span class="kt">void</span> <span class="nf">run</span><span class="o">()</span> <span class="o">{</span>
<span class="hll">              <span class="n">setText</span><span class="o">(</span><span class="n">callable</span><span class="o">.</span><span class="na">call</span><span class="o">(</span><span class="n">message</span><span class="o">));</span>
</span>            <span class="o">}</span>
          <span class="o">});</span>
        <span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
          <span class="n">post</span><span class="o">(</span><span class="k">new</span> <span class="n">Runnable</span><span class="o">()</span> <span class="o">{</span>
            <span class="nd">@Override</span>
            <span class="kd">public</span> <span class="kt">void</span> <span class="nf">run</span><span class="o">()</span> <span class="o">{</span>
<span class="hll">              <span class="n">setText</span><span class="o">(</span><span class="n">message</span><span class="o">.</span><span class="na">toString</span><span class="o">());</span>
</span>            <span class="o">}</span>
          <span class="o">});</span>
        <span class="o">}</span>
        <span class="n">postInvalidate</span><span class="o">();</span>
      <span class="o">}</span>
    <span class="o">});</span>
  <span class="o">}</span>

  <span class="nd">@Override</span>
  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">onShutdown</span><span class="o">(</span><span class="n">Node</span> <span class="n">node</span><span class="o">)</span> <span class="o">{</span>
  <span class="o">}</span>

  <span class="nd">@Override</span>
  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">onShutdownComplete</span><span class="o">(</span><span class="n">Node</span> <span class="n">node</span><span class="o">)</span> <span class="o">{</span>
  <span class="o">}</span>

  <span class="nd">@Override</span>
  <span class="kd">public</span> <span class="kt">void</span> <span class="nf">onError</span><span class="o">(</span><span class="n">Node</span> <span class="n">node</span><span class="o">,</span> <span class="n">Throwable</span> <span class="n">throwable</span><span class="o">)</span> <span class="o">{</span>
  <span class="o">}</span>
<span class="o">}</span>
</pre></div>
</td></tr></table></div>
<p>The view is configured with a topic name, message type, and a
<a class="reference external" href="javadoc/org/ros/android/MessageCallable.html#">MessageCallable</a>. On line 40, in the
<a class="reference external" href="javadoc/org/ros/node/NodeMain.html#onStart(Node)">NodeMain.onStart</a> method, we create a new
<a class="reference external" href="javadoc/org/ros/node/topic/Subscriber.html#">Subscriber</a> for the configured topic and message
type.</p>
<p>When a new message arrives, we either use the configured callable to transform
the incoming message to a string (line 49), or we use the default
<tt class="docutils literal"><span class="pre">toString()</span></tt> method if no callable was configured (line 56). We then set the
text of the view to the string representation of the incoming message.</p>
<p>As with any other <a class="reference external" href="javadoc/org/ros/node/NodeMain.html#">NodeMain</a>, the
<a class="reference external" href="javadoc/org/ros/android/view/RosTextView.html#">RosTextView</a> must be executed by the
<a class="reference external" href="javadoc/org/ros/node/NodeMainExecutor.html#">NodeMainExecutor</a>. In the <a class="reference internal" href="#life-of-a-rosactivity"><em>Using RosActivity</em></a>
example, we execute it in
<a class="reference external" href="javadoc/org/ros/android/RosActivity.html#init(NodeMainExecutor)">RosActivity.init</a> and use the it to
display incoming messages from the
<a class="reference external" href="javadoc/org/ros/rosjava_tutorial_pubsub/Talker.html#">Talker</a> node.</p>
</div>
</div>


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