Make SLAM view easier to implement in multiple protocols.

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

@@ -0,0 +1,36 @@
+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

@@ -3,67 +3,69 @@ package com.example.carcontroller.SLAM;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.util.AttributeSet;
+import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 
 import androidx.preference.PreferenceManager;
 
-import com.example.carcontroller.SlamScan;
-import com.google.protobuf.InvalidProtocolBufferException;
+import com.example.carcontroller.SlamLocation;
+import com.google.protobuf.ByteString;
 
-import org.zeromq.SocketType;
-import org.zeromq.ZContext;
-import org.zeromq.ZMQ;
+public class SlamView extends SurfaceView implements SlamUpdater.MapChangedListener {
 
-public class SlamView extends SurfaceView implements Runnable {
-
-    ZContext context;
-    String host;
-    String port;
+    SlamUpdater slam;
     Thread mapThread;
+    Context context;
+    private int width;
+    private int height;
+    private SurfaceHolder surfaceHolder;
 
     public SlamView(Context context) {
         super(context);
+        this.context = context;
         init();
     }
 
     public SlamView(Context context, AttributeSet attrs) {
         super(context, attrs);
+        this.context = context;
         init();
     }
 
     public SlamView(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
+        this.context = context;
         init();
     }
 
     private void init() {
-        context = new ZContext();
-        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
-        host = prefs.getString("host", "10.0.0.53");
-        port = prefs.getString("zmqPort", "5050");
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        String host = prefs.getString("host", "10.0.0.53");
+        String port = prefs.getString("zmqPort", "5050");
+        slam = new ZmqSlamUpdater(host, port);
+        slam.addMapChangedListener(this);
     }
 
-    @Override
-    public void run() {
-        // Receive map from zmq and update appropriately.
-        try (ZMQ.Socket socket = context.createSocket(SocketType.PAIR)) {
-            socket.connect("tcp://" + host + ":" + port);
-            socket.send("Hi");
-            while (!Thread.currentThread().isInterrupted()) {
-                byte[] map = socket.recv();
-                SlamScan scan = SlamScan.parseFrom(map);
-                for (Byte b : scan.getMap()) {
-
-                }
-            }
-        } catch (InvalidProtocolBufferException e) {
-            System.out.println("Invalid map found");
-        }
-
+    /**
+     * Called by MainActivity.onResume() to start a thread.
+     */
+    public void resume() {
+        mapThread = new Thread(slam);
+        mapThread.start();
     }
 
     public void stop() {
         // Use grpc to tell the loader to stop. Interrupt the loader thread as well.
-        mapThread.interrupt();
+        slam.stop();
+        try {
+            mapThread.join();
+        } catch (InterruptedException e) {
+
+        }
+    }
+
+    @Override
+    public void mapChanged(ByteString map, SlamLocation location) {
+
     }
 }

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

@@ -0,0 +1,59 @@
+package com.example.carcontroller.SLAM;
+
+import com.example.carcontroller.SlamScan;
+import com.google.protobuf.InvalidProtocolBufferException;
+
+import org.zeromq.SocketType;
+import org.zeromq.ZContext;
+import org.zeromq.ZMQ;
+
+/**
+ * Connects to Pi and retrieves updates of the SLAM map,
+ * notifying listeners of changes to the map when they arrive.
+ * Uses 0MQ for the transport.
+ */
+public class ZmqSlamUpdater extends SlamUpdater {
+
+    private ZContext context;
+    private String host;
+    private String port;
+    private boolean running = false;
+
+    public ZmqSlamUpdater(String host, String port) {
+        super();
+        this.host = host;
+        this.port = port;
+        init();
+    }
+
+    @Override
+    protected void init() {
+        context = new ZContext();
+    }
+
+
+    @Override
+    public void run() {
+        // Should send a gRPC message to start listening...
+
+
+        running = true;
+        // Receive map from zmq and update appropriately.
+        try (ZMQ.Socket socket = context.createSocket(SocketType.PAIR)) {
+            socket.connect("tcp://" + host + ":" + port);
+            socket.send("Hi");
+            while (running) {
+                byte[] map = socket.recv();
+                fireMapChanged(SlamScan.parseFrom(map));
+            }
+        } catch (InvalidProtocolBufferException e) {
+            System.out.println("Invalid map found");
+            running = false;
+        }
+    }
+
+
+    public void stop() {
+        running = false;
+    }
+}