问WP8指南针应用程序问题

EN

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using Microsoft.Devices.Sensors;


namespace PhoneApp4
{
public partial class CompassScreen : PhoneApplicationPage
{
    Compass compass = new Compass();
    RotateTransform transform = new RotateTransform();
    double TrueHeading;
    double ReciprocalHeading;
    double HeadingAccuracy;
    bool Alphabetic = false; //alpha output setting, default is false
    bool Calibrating = false;

     // Constructor
    public CompassScreen()
  {
       try
       {
            InitializeComponent();
            compass.CurrentValueChanged += new      EventHandler<SensorReadingEventArgs<CompassReading>>(compass_CurrentValueChanged);
            compass.Calibrate += new EventHandler<CalibrationEventArgs>(compass_Calibrate);

compass.CurrentValueChanged
compass.Calibrate