Make SLAM view easier to implement in multiple protocols.

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;
+    }
+}