Minor upgrades to android lidar support

app/src/main/java/org/vato/carcontroller/LIDAR/LidarView.java

@@ -7,6 +7,7 @@ import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.util.AttributeSet;
+import android.util.Log;
 import android.view.MotionEvent;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
@@ -115,8 +116,22 @@ public class LidarView extends SurfaceView
 
 
     public void stop() {
-        // TODO: Use grpc to tell zmq to stop.
         lidar.stop();
+        StreamObserver<Empty> responseObserver = new StreamObserver<Empty>() {
+            @Override
+            public void onNext(Empty value) {
+            }
+
+            @Override
+            public void onError(Throwable t) {
+                Log.d("LIDAR", "Failed to stop SLAM", t);
+            }
+
+            @Override
+            public void onCompleted() {
+            }
+        };
+        stub.stopTracking(Empty.newBuilder().build(), responseObserver);
         try {
             lidarThread.join(1000);
         } catch (InterruptedException e) {
@@ -141,6 +156,15 @@ public class LidarView extends SurfaceView
         }
     }
 
+    /**
+     *
+     * @param groupNumber
+     * @return
+     */
+    private static int convertGroupNumberToHue(int groupNumber){
+        return 0;
+    }
+
     private static class Point {
         private double x;
         private double y;

app/src/main/java/org/vato/carcontroller/SLAM/SlamView.java

@@ -7,6 +7,7 @@ import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.util.AttributeSet;
+import android.util.Log;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 
@@ -128,6 +129,20 @@ public class SlamView extends SurfaceView implements AbstractUpdater.MapChangedL
     public void stop() {
         // TODO: Use grpc to tell zmq to stop.
         slam.stop();
+        stub.stopStreaming(Empty.newBuilder().build(), new StreamObserver<Empty>() {
+            @Override
+            public void onNext(Empty value) {
+            }
+
+            @Override
+            public void onError(Throwable t) {
+                Log.d("SLAM", "Failed to stop SLAM", t);
+            }
+
+            @Override
+            public void onCompleted() {
+            }
+        });
         try {
             mapThread.join(1000);
         } catch (InterruptedException e) {

app/src/main/java/org/vato/carcontroller/Updaters/GrpcUpdater.java

@@ -17,6 +17,7 @@ public class GrpcUpdater<T extends MessageLite> extends AbstractUpdater<T> {
 
     @Override
     public void stop() {
+        // TODO... may not be needed here.
 
     }