Windows Phone 7（accelerometer）重力感应编程

使用重力感应器accelerometer，需要引用类库Microsoft.Devices.Sensors ，所以需要在WMAppManifest.xml
加上
 <Capability Name="ID_CAP_SENSORS" />

using System;
using System.Security;

namespace Microsoft.Devices.Sensors
{
    // Summary:
    //     Provides Windows?Phone applications access to the device’s accelerometer
    //     sensor.
    public sealed class Accelerometer : IDisposable
    {
        // Summary:
        //     Creates a new instance of the Microsoft.Devices.Sensors.Accelerometer object.
        [SecuritySafeCritical]
        public Accelerometer();

        // Summary:
        //     Gets the current state of the accelerometer. The value is a member of the
        //     Microsoft.Devices.Sensors.SensorState enumeration.
        //
        // Returns:
        //     Type Microsoft.Devices.Sensors.SensorState.
        public SensorState State { get; }

        // Summary:
        //     Occurs when new data arrives from the accelerometer.
        public event EventHandler<AccelerometerReadingEventArgs> ReadingChanged;

        // Summary:
        //     Releases the managed and unmanaged resources used by the Microsoft.Devices.Sensors.Accelerometer.
        [SecuritySafeCritical]
        public void Dispose();
        //
        // Summary:
        //     Starts data acquisition from the accelerometer.
        [SecuritySafeCritical]
        public void Start();
        //
        // Summary:
        //     Stops data acquisition from the accelerometer.
        [SecuritySafeCritical]
        public void Stop();
    }
}

X轴表示左右方向的重力大小 

Y轴表示上下方向的重力大小 

Z轴表示屏幕正上方下面的的重力大小 

实例

MainPage.xaml
<phone:PhoneApplicationPage 
    x:Class="SilverlightAccelerometer.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="PortraitOrLandscape" Orientation="Portrait"
    mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768"
    shell:SystemTray.IsVisible="True">

    <!--LayoutRoot contains the root grid where all other page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="SILVERLIGHT ACCELEROMETER" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock x:Name="PageTitle" Text="main page" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <TextBlock Name="txtblk"
                        HorizontalAlignment="Center"
                        VerticalAlignment="Center" />
        </Grid>
    </Grid>
</phone:PhoneApplicationPage>

MainPage.xaml.cs
using System;
using System.Windows;
using System.Windows.Controls;
using Microsoft.Devices.Sensors;
using Microsoft.Phone.Controls;

namespace SilverlightAccelerometer
{
    public partial class MainPage : PhoneApplicationPage
    {
        public MainPage()
        {
            InitializeComponent();

            Accelerometer acc = new Accelerometer();//初始化一个重力感应器的类
            acc.ReadingChanged += OnAccelerometerReadingChanged;//触发重力感应的事件

            try
            {
                acc.Start();//开始加速计重力感应
            }
            catch (Exception exc)
            {
                txtblk.Text = exc.Message;
            }
        }

        void OnAccelerometerReadingChanged(object sender, AccelerometerReadingEventArgs args)
        {
            string str = String.Format("X = {0:F2}\n" +     //x轴表示屏幕的左右  
                                       "Y = {1:F2}\n" +      //y轴表示屏幕的上下 
                                       "Z = {2:F2}\n\n" +    //z轴表示屏幕正上方的上下 
                                       "Magnitude = {3:F2}\n\n" +
                                       "{4}", 
                                       args.X, args.Y, args.Z, 
                                       Math.Sqrt(args.X * args.X + args.Y * args.Y +   //计算加速度
                                                                   args.Z * args.Z),                                       
                                       args.Timestamp);

            if (txtblk.CheckAccess())//判断线程是否允许访问
            {
                SetTextBlockText(txtblk, str);
            }
            else
            {
                //重新激活线程
                txtblk.Dispatcher.BeginInvoke(new SetTextBlockTextDelegate(SetTextBlockText), 
                                              txtblk, str);
            }
        }

        delegate void SetTextBlockTextDelegate(TextBlock txtblk, string text);

        void SetTextBlockText(TextBlock txtblk, string text)
        {
            txtblk.Text = text;
        }
    }
}