Finish off SlamController

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

@@ -2,6 +2,10 @@ package com.example.carcontroller.SLAM;
 
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
 import android.util.AttributeSet;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
@@ -13,12 +17,12 @@ import com.google.protobuf.ByteString;
 
 public class SlamView extends SurfaceView implements SlamUpdater.MapChangedListener {
 
-    SlamUpdater slam;
-    Thread mapThread;
-    Context context;
+    private SlamUpdater slam;
+    private Thread mapThread;
+    private Context context;
     private int width;
-    private int height;
     private SurfaceHolder surfaceHolder;
+    private Paint paint;
 
     public SlamView(Context context) {
         super(context);
@@ -44,6 +48,9 @@ public class SlamView extends SurfaceView implements SlamUpdater.MapChangedListe
         String port = prefs.getString("zmqPort", "5050");
         slam = new ZmqSlamUpdater(host, port);
         slam.addMapChangedListener(this);
+        surfaceHolder = getHolder();
+        paint = new Paint();
+        paint.setColor(Color.BLUE);
     }
 
     /**
@@ -66,6 +73,27 @@ public class SlamView extends SurfaceView implements SlamUpdater.MapChangedListe
 
     @Override
     public void mapChanged(ByteString map, SlamLocation location) {
+        if (surfaceHolder.getSurface().isValid()) {
+            Canvas canvas = surfaceHolder.lockCanvas();
+            canvas.save();
+            canvas.drawColor(Color.WHITE);
+            // Using width as we want square.
+            Bitmap bitmap = Bitmap.createBitmap(width, width, Bitmap.Config.ALPHA_8);
+            for (int i = 0; i < width; i++) {
+                for (int j = 0; j < width; j++) {
+                    // 0-255 is appropriate for the config used.
+                    bitmap.setPixel(i, j, map.byteAt(i * width + j));
+                }
+            }
+            canvas.drawBitmap(bitmap, 0, 0, paint);
+            canvas.restore();
+            surfaceHolder.unlockCanvasAndPost(canvas);
+        }
+    }
 
+    @Override
+    protected void onSizeChanged(int w, int b, int oldW, int oldB) {
+        super.onSizeChanged(w, b, oldW, oldB);
+        width = w;
     }
 }