Fixes an outdated comment.

Fixes a potential NPE caused by a race condition between node and view initialization.
Cleans up enabling and disabling follow me mode.

android_gingerbread_mr1/src/org/ros/android/RosActivity.java

@@ -93,7 +93,8 @@ public abstract class RosActivity extends Activity {
       nodeMainExecutorService.shutdown();
       unbindService(nodeMainExecutorServiceConnection);
       // NOTE(damonkohler): The activity could still be restarted. In that case,
-      // nodeRunner needs to be null for everything to be started up again.
+      // nodeMainExectuorService needs to be null for everything to be started
+      // up again.
       nodeMainExecutorService = null;
     }
     Toast.makeText(this, notificationTitle + " shut down.", Toast.LENGTH_SHORT).show();

android_honeycomb_mr2/src/org/ros/android/view/visualization/VisualizationView.java

@@ -24,6 +24,7 @@ import android.opengl.GLSurfaceView;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import org.ros.android.view.visualization.layer.Layer;
+import org.ros.exception.RosRuntimeException;
 import org.ros.message.MessageListener;
 import org.ros.namespace.GraphName;
 import org.ros.namespace.NameResolver;
@@ -34,20 +35,22 @@ import org.ros.node.topic.Subscriber;
 import org.ros.rosjava_geometry.FrameTransformTree;
 
 import java.util.List;
+import java.util.concurrent.CountDownLatch;
 
 /**
+ * @author damonkohler@google.com (Damon Kohler)
  * @author moesenle@google.com (Lorenz Moesenlechner)
  */
 public class VisualizationView extends GLSurfaceView implements NodeMain {
 
   private static final boolean DEBUG = false;
 
-  // Initialized here to avoid constructor code duplication.
   private final NameResolver nameResolver = NameResolver.newRoot();
   private final FrameTransformTree frameTransformTree = new FrameTransformTree(nameResolver);
   private final Camera camera = new Camera(frameTransformTree);
   private final XYOrthographicRenderer renderer = new XYOrthographicRenderer(camera);
   private final List<Layer> layers = Lists.newArrayList();
+  private final CountDownLatch attachedToWindow = new CountDownLatch(1);
 
   private ConnectedNode connectedNode;
 
@@ -114,9 +117,22 @@ public class VisualizationView extends GLSurfaceView implements NodeMain {
   public void onStart(ConnectedNode connectedNode) {
     this.connectedNode = connectedNode;
     startTransformListener();
+    try {
+      attachedToWindow.await();
+    } catch (InterruptedException e) {
+      throw new RosRuntimeException(e);
+    }
+    // startLayers() must be called after we've attached to the window in order
+    // to ensure that getHandler() will not return null.
     startLayers();
   }
 
+  @Override
+  protected void onAttachedToWindow() {
+    super.onAttachedToWindow();
+    attachedToWindow.countDown();
+  }
+
   private void startTransformListener() {
     Subscriber<tf.tfMessage> tfSubscriber = connectedNode.newSubscriber("tf", tf.tfMessage._TYPE);
     tfSubscriber.addMessageListener(new MessageListener<tf.tfMessage>() {

android_tutorial_map_viewer/AndroidManifest.xml

@@ -16,8 +16,8 @@
         android:label="@string/app_name" >
         <activity
             android:name="org.ros.android.android_tutorial_map_viewer.MainActivity"
-            android:label="@string/app_name"
-            android:screenOrientation="landscape" >
+            android:configChanges="orientation|keyboardHidden|screenSize"
+            android:label="@string/app_name" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
@@ -29,4 +29,4 @@
         <service android:name="org.ros.android.NodeMainExecutorService" />
     </application>
 
-</manifest>
+</manifest>

android_tutorial_map_viewer/src/org/ros/android/android_tutorial_map_viewer/MainActivity.java

@@ -81,15 +81,6 @@ public class MainActivity extends RosActivity {
         disableFollowMe();
       }
 
-      private void disableFollowMe() {
-        runOnUiThread(new Runnable() {
-          @Override
-          public void run() {
-            visualizationView.getCamera().setFrame(MAP_FRAME);
-            followMeToggleButton.setChecked(false);
-          }
-        });
-      }
     });
     visualizationView.addLayer(cameraControlLayer);
     visualizationView.addLayer(new CompressedOccupancyGridLayer("map/png"));
@@ -127,9 +118,29 @@ public class MainActivity extends RosActivity {
   public void onFollowMeToggleButtonClicked(View view) {
     boolean on = ((ToggleButton) view).isChecked();
     if (on) {
-      visualizationView.getCamera().jumpToFrame(ROBOT_FRAME);
+      enableFollowMe();
     } else {
-      visualizationView.getCamera().setFrame(MAP_FRAME);
+      disableFollowMe();
     }
   }
+
+  private void enableFollowMe() {
+    runOnUiThread(new Runnable() {
+      @Override
+      public void run() {
+        visualizationView.getCamera().jumpToFrame(ROBOT_FRAME);
+        followMeToggleButton.setChecked(true);
+      }
+    });
+  }
+
+  private void disableFollowMe() {
+    runOnUiThread(new Runnable() {
+      @Override
+      public void run() {
+        visualizationView.getCamera().setFrame(MAP_FRAME);
+        followMeToggleButton.setChecked(false);
+      }
+    });
+  }
 }