Add onDoubleTap to CameraControlListener

The user of a visualization view can now use the double tap gesture and
obtain the tapped position in the camera frame.

This could be useful to use the map as a way of sensing navigation
goals by tapping.

Adds the onDoubleTap method to CameraControlListener. This breaks
previous code that does not override that method. The map_viewer
tutorial is updated in this commit.

android_15/src/org/ros/android/view/visualization/layer/CameraControlLayer.java

@@ -28,6 +28,7 @@ import org.ros.concurrent.ListenerGroup;
 import org.ros.concurrent.SignalRunnable;
 import org.ros.node.ConnectedNode;
 import org.ros.node.NodeMainExecutor;
+import org.ros.rosjava_geometry.Vector3;
 
 /**
  * Provides gesture control of the camera for translate, rotate, and zoom.
@@ -91,6 +92,20 @@ public class CameraControlLayer extends DefaultLayer {
                 });
                 return true;
               }
+
+              @Override
+              public boolean onDoubleTap (MotionEvent e) {
+                float x = e.getX();
+                float y = e.getY();
+                final Vector3 tapVector = view.getCamera().toCameraFrame((int)x, (int)y);
+                listeners.signal(new SignalRunnable<CameraControlListener>() {
+                  @Override
+                  public void run(CameraControlListener listener) {
+                    listener.onDoubleTap(tapVector);
+                  }
+                });
+                return true;
+              }
             });
         rotateGestureDetector =
             new RotateGestureDetector(new RotateGestureDetector.OnRotateGestureListener() {

android_15/src/org/ros/android/view/visualization/layer/CameraControlListener.java

@@ -16,6 +16,8 @@
 
 package org.ros.android.view.visualization.layer;
 
+import org.ros.rosjava_geometry.Vector3;
+
 /**
  * @author damonkohler@google.com (Damon Kohler)
  */
@@ -25,4 +27,6 @@ public interface CameraControlListener {
   void onRotate(double focusX, double focusY, double deltaAngle);
 
   void onZoom(double focusX, double focusY, double factor);
+
+  void onDoubleTap(Vector3 tap);
 }

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

@@ -36,6 +36,7 @@ import org.ros.android.view.visualization.layer.OccupancyGridLayer;
 import org.ros.android.view.visualization.layer.RobotLayer;
 import org.ros.node.NodeConfiguration;
 import org.ros.node.NodeMainExecutor;
+import org.ros.rosjava_geometry.Vector3;
 import org.ros.time.NtpTimeProvider;
 
 import java.util.concurrent.TimeUnit;
@@ -90,6 +91,9 @@ public class MainActivity extends RosActivity {
         disableFollowMe();
       }
 
+      @Override
+      public void onDoubleTap(Vector3 tap) {
+      }
     });
     NodeConfiguration nodeConfiguration =
         NodeConfiguration.newPublic(InetAddressFactory.newNonLoopback().getHostAddress(),