Provide a generic way to receive zmq updates for lidar and slam.

.idea/misc.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_9" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">

app/build.gradle

@@ -19,8 +19,8 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility = 1.8
+        sourceCompatibility = 9.8
-        targetCompatibility = 1.8
+        targetCompatibility = 9.8
     }
 }
 

app/src/main/AndroidManifest.xml

@@ -13,7 +13,7 @@
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
         <activity android:name=".SLAM.SlamController"></activity>
-        <activity android:name=".LidarTrackingController" />
+        <activity android:name=".LIDAR.LidarTrackingController" />
         <activity
             android:name=".SettingsActivity"
             android:label="@string/title_activity_settings"

app/src/main/java/com/example/carcontroller/LIDAR/LidarTrackingController.java

@@ -1,8 +1,10 @@
-package com.example.carcontroller;
+package com.example.carcontroller.LIDAR;
+
+import android.os.Bundle;
 
 import androidx.appcompat.app.AppCompatActivity;
 
-import android.os.Bundle;
+import com.example.carcontroller.R;
 
 public class LidarTrackingController extends AppCompatActivity {
 

app/src/main/java/com/example/carcontroller/LIDAR/LidarView.java

@@ -1,4 +1,4 @@
-package com.example.carcontroller;
+package com.example.carcontroller.LIDAR;
 
 import android.content.Context;
 import android.graphics.Bitmap;
@@ -8,6 +8,8 @@ import android.view.MotionEvent;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 
+import com.example.carcontroller.PersonTrackingGrpc;
+
 public class LidarView extends SurfaceView implements Runnable {
 
     private boolean running;

app/src/main/java/com/example/carcontroller/MainActivity.java

@@ -1,22 +1,17 @@
 package com.example.carcontroller;
 
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.appcompat.widget.Toolbar;
-
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.Menu;
-import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
-import android.widget.SeekBar;
 
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.Toolbar;
+
+import com.example.carcontroller.LIDAR.LidarTrackingController;
 import com.example.carcontroller.SLAM.SlamController;
 
-import java.util.concurrent.CountDownLatch;
-
-import io.grpc.stub.StreamObserver;
-
 public class MainActivity extends AppCompatActivity {
 
 

app/src/main/java/com/example/carcontroller/SLAM/SlamUpdater.java

@@ -1,36 +0,0 @@
-package com.example.carcontroller.SLAM;
-
-import com.example.carcontroller.SlamLocation;
-import com.example.carcontroller.SlamScan;
-import com.google.protobuf.ByteString;
-
-import java.util.HashSet;
-import java.util.Set;
-
-public abstract class SlamUpdater implements Runnable {
-
-    private Set<MapChangedListener> listeners;
-
-    public SlamUpdater() {
-        init();
-    }
-
-    protected void init() {
-        listeners = new HashSet<>();
-    }
-
-    public void addMapChangedListener(MapChangedListener listener) {
-        listeners.add(listener);
-    }
-
-
-    protected void fireMapChanged(SlamScan scan) {
-        listeners.forEach(listener -> listener.mapChanged(scan.getMap(), scan.getLocation()));
-    }
-
-    public abstract void stop();
-
-    public interface MapChangedListener {
-        void mapChanged(ByteString map, SlamLocation location);
-    }
-}

app/src/main/java/com/example/carcontroller/SLAM/SlamView.java

@@ -16,21 +16,25 @@ import com.example.carcontroller.Empty;
 import com.example.carcontroller.SlamControlGrpc;
 import com.example.carcontroller.SlamDetails;
 import com.example.carcontroller.SlamLocation;
+import com.example.carcontroller.SlamScan;
+import com.example.carcontroller.Updaters.AbstractUpdater;
+import com.example.carcontroller.Updaters.ZmqUpdater;
 import com.google.protobuf.ByteString;
 
 import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
 import io.grpc.stub.StreamObserver;
 
-public class SlamView extends SurfaceView implements SlamUpdater.MapChangedListener {
+public class SlamView extends SurfaceView implements AbstractUpdater.MapChangedListener<SlamScan> {
 
-    private SlamUpdater slam;
+    private static final String SLAM_TOPIC = "slam_map";
+
+    private AbstractUpdater<SlamScan> slam;
     private Thread mapThread;
     private Context context;
     private SurfaceHolder surfaceHolder;
     private Paint paint;
     private SlamControlGrpc.SlamControlStub stub;
-    private ManagedChannel channel;
     private int mapSizePixels;
     private int mapSizeMeters;
     private String port;
@@ -60,15 +64,14 @@ public class SlamView extends SurfaceView implements SlamUpdater.MapChangedListe
         String gRPCPort = prefs.getString("port", "50051");
         mapSizePixels = Integer.parseInt(prefs.getString("MAPSIZEPIXELS", "540"));
         mapSizeMeters = Integer.parseInt(prefs.getString("MAPSIZEMETRES", "10"));
-        slam = new ZmqSlamUpdater(host, port);
+        slam = new ZmqUpdater<>(SlamScan.getDefaultInstance().getParserForType(), SLAM_TOPIC, host, port);
         slam.addMapChangedListener(this);
         surfaceHolder = getHolder();
         paint = new Paint();
         paint.setColor(Color.BLUE);
         mapThread = new Thread(slam);
-        channel = ManagedChannelBuilder.forAddress(host, Integer.parseInt(gRPCPort)).usePlaintext().build();
+        ManagedChannel channel = ManagedChannelBuilder.forAddress(host, Integer.parseInt(gRPCPort)).usePlaintext().build();
         stub = SlamControlGrpc.newStub(channel);
-
     }
 
     /**
@@ -106,12 +109,15 @@ public class SlamView extends SurfaceView implements SlamUpdater.MapChangedListe
         try {
             mapThread.join();
         } catch (InterruptedException e) {
-
         }
     }
 
     @Override
-    public void mapChanged(ByteString map, SlamLocation location) {
+    public void mapChanged(SlamScan scan) {
+        updateView(scan.getMap(), scan.getLocation());
+    }
+
+    private void updateView(ByteString map, SlamLocation location) {
         if (surfaceHolder.getSurface().isValid()) {
             Canvas canvas = surfaceHolder.lockCanvas();
             canvas.save();

app/src/main/java/com/example/carcontroller/Updaters/AbstractUpdater.java

@@ -0,0 +1,51 @@
+package com.example.carcontroller.Updaters;
+
+import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.MessageLite;
+import com.google.protobuf.Parser;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Provides an abstract way to receive updates from a remote host (i.e. the rc car).
+ * Subclasses of this implement the approriate connection mechanisms to continuously receive
+ * new updates of messages.
+ * Specifically, protobuf serialisation support is provided
+ *
+ * @param <T> The message type that will continuously be received
+ */
+public abstract class AbstractUpdater<T extends MessageLite> implements Runnable {
+
+    private Set<MapChangedListener<T>> listeners;
+    private Parser<T> parser;
+
+    public AbstractUpdater(Parser<T> parser) {
+        this.parser = parser;
+        init();
+    }
+
+    protected void init() {
+        listeners = new HashSet<>();
+    }
+
+    public void addMapChangedListener(MapChangedListener<T> listener) {
+        listeners.add(listener);
+    }
+
+
+    protected void fireMapChanged(T scan) {
+        listeners.forEach(listener -> listener.mapChanged(scan));
+    }
+
+    public abstract void stop();
+
+    public interface MapChangedListener<T extends MessageLite> {
+        void mapChanged(T points);
+    }
+
+    protected T parseMessage(byte[] messageBytes) throws InvalidProtocolBufferException {
+        return parser.parseFrom(messageBytes);
+    }
+
+}

app/src/main/java/com/example/carcontroller/Updaters/ZmqUpdater.java

@@ -1,7 +1,8 @@
-package com.example.carcontroller.SLAM;
+package com.example.carcontroller.Updaters;
 
-import com.example.carcontroller.SlamScan;
 import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.MessageLite;
+import com.google.protobuf.Parser;
 
 import org.zeromq.SocketType;
 import org.zeromq.ZContext;
@@ -10,20 +11,21 @@ import org.zeromq.ZMQ;
 import java.util.Arrays;
 
 /**
- * Connects to Pi and retrieves updates of the SLAM map,
+ * Provides a way to easily deal with zeromq sub sockets that use protobuf
- * notifying listeners of changes to the map when they arrive.
+ *
- * Uses 0MQ for the transport.
+ * @param <T>
  */
-public class ZmqSlamUpdater extends SlamUpdater {
+public class ZmqUpdater<T extends MessageLite> extends AbstractUpdater<T> {
 
     private ZContext context;
     private String host;
     private String port;
     private boolean running = false;
-    private static final byte[] SLAM_SUBSCRIPTION = "slam_map".getBytes();
+    private final byte[] SUBSCRIPTION;
 
-    public ZmqSlamUpdater(String host, String port) {
+    public ZmqUpdater(Parser<T> parser, String topic, String host, String port) {
-        super();
+        super(parser);
+        this.SUBSCRIPTION = topic.getBytes();
         this.host = host;
         this.port = port;
         init();
@@ -42,12 +44,12 @@ public class ZmqSlamUpdater extends SlamUpdater {
         // Receive map from zmq and update appropriately.
         try (ZMQ.Socket socket = context.createSocket(SocketType.SUB)) {
             socket.connect("tcp://" + host + ":" + port);
-            socket.subscribe(SLAM_SUBSCRIPTION);
+            socket.subscribe(SUBSCRIPTION);
             while (running) {
                 byte[] map = socket.recv();
                 // Don't want to do the event when we just receive the header.
-                if (!Arrays.equals(map, SLAM_SUBSCRIPTION)) {
+                if (!Arrays.equals(map, SUBSCRIPTION)) {
-                    fireMapChanged(SlamScan.parseFrom(map));
+                    fireMapChanged(parseMessage(map));
                 }
             }
         } catch (InvalidProtocolBufferException e) {

app/src/main/res/layout-land/activity_lidar_tracking_controller.xml

@@ -4,9 +4,9 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context=".LidarTrackingController">
+    tools:context=".LIDAR.LidarTrackingController">
 
-    <com.example.carcontroller.LidarView
+    <com.example.carcontroller.LIDAR.LidarView
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:id="@+id/lidarMap"/>

app/src/main/res/layout/activity_lidar_tracking_controller.xml

@@ -4,7 +4,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context=".LidarTrackingController">
+    tools:context=".LIDAR.LidarTrackingController">
 
     <TextView
         android:layout_width="wrap_content"