@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);

    width = w;
    height = h;

    mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.floor_plan1).copy(Bitmap.Config.ARGB_8888, true);
    mBitmap.setHasAlpha(true);
    mCanvas = new Canvas(mBitmap);
}

public static void login(String username, String password, String ipAddress, final Callback callback) throws JSONException {

    OkHttpClient client = new OkHttpClient();

    JSONObject jsonObject = new JSONObject();
    jsonObject.put("username", username);
    jsonObject.put("password", password);
    jsonObject.put("ip", ipAddress);

    RequestBody body = RequestBody.create(MediaType.parse("application/json"), jsonObject.toString());
    Request request = new Request.Builder()
            .url("http://"+ipAddress+"/api/v0/login")
            .post(body)
            .build();

    client.newCall(request).enqueue(new com.squareup.okhttp.Callback() {


        // produces exception if db connection request has fail
        @Override
        public void onFailure(Request request, IOException e) {
            callback.onLoginFailure(e);
        }

        // checks is db request passed or fail
        @Override public void onResponse(Response response){
            if (!response.isSuccessful()) {
                callback.onLoginFailure(new IOException("Unexpected code " + response));
                return;
            }

            String jsonAsString = null;

            try {
                jsonAsString = response.body().string();

                JSONObject json = new JSONObject(jsonAsString);

                if (json.getString("status").equals("ok")){

                    Device device = new Device();
                    device.locationID = json.getInt("location_id");
                    device.imageID = json.getInt("imageId");
                    device.imageName = json.getString("imageName");

                    device.id = json.getInt("id");

                    Device.instance = device;

                    callback.onLoginSuccess(device);
                } else {
                    throw new JSONException("Invalid service response");
                }

            } catch (Exception e) {
                e.printStackTrace();
                callback.onLoginFailure(e);
            }
        }
    });
}
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    activity = this;
    // declaring variables
    etUsername = (EditText)findViewById(R.id.etUsername);
    etPassword= (EditText)findViewById(R.id.etPassword);
    btnLogin = (Button)findViewById(R.id.btnLogin);
    etIpAddress = (EditText) findViewById(R.id.etIpAddress);
    final String username = etUsername.getText().toString();
    final String password = etPassword.getText().toString();
    final String ipAddress = etIpAddress.getText().toString();

    Device device = new Device();
    device.validateLogin(username, password, ipAddress);

    // setting up things for login button
    btnLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            String ipAddress = etIpAddress.getText().toString();

            String username = etUsername.getText().toString().trim();
            String password = etPassword.getText().toString().trim();

            Device device = new Device();
            device.saveSP(username, password, ipAddress);

            performLogin(username, password, ipAddress);
        }
    });
}