题外话

     首先感谢一直关注我博客的博友们&＃xff01;使我有动力一直写下去。通过几个月对Windows Phone7的学习后&＃xff0c;对它又有了更深入的学习和了解&＃xff0c;所以我又开了一个新章节&＃xff0c;来把我学到的东西分享出来。也希望大家继续支持我&＃xff0c;一起进步。

Reactive Extension for .Net framework

.Net反应性框架&＃xff0c;在之前的.net框架中就已经有了&＃xff0c;没想到也被应用到Windows phone7中来了。

程序员为指定异步操作指定回调&＃xff0c;或事件处理程序的时候使用反应性编程。在异步操作完成或者事件触发的时候&＃xff0c;就会调用方法并作为对该事件的反应。在这个模型中&＃xff0c;数据流、异步请求、事件都可以做为可观察序列&＃xff0c;并且接收异步消息&＃xff0c;并通过LINQ来合成这些序列。

不过在Phone7中&＃xff0c;这个框架只有一部分有用&＃xff0c;主要用在&＃xff1a;filtering events、composing multiple asynchronous web service requests、emulating data streams.

 

对于目前来说&＃xff0c;在模拟器上没有办法测试Accelerometer和Location的API&＃xff0c;就是因为得不到数据。现在可以利用这个框架来实现数据模拟了。

 

模拟Accelerometer数据&＃xff1a;

Thread thread &＃61; new Thread(StartAccelerometerEmulation);

thread.Start();

 

am &＃61; new Accelerometer();

var aro &＃61; Observable.FromEvent<AccelerometerReadingEventArgs>(

eh &＃61;> am.ReadingChanged &＃43;&＃61; eh,

eh &＃61;> am.ReadingChanged -&＃61; eh);

 

try

{

     am.Start();

}

catch (AccelerometerFailedException ae)

{

}

 

void InvokeAccelerometerReadingChanged(Vector3 data)

{

    Deployment.Current.Dispatcher.BeginInvoke(() &＃61;> AccelerometerReadingChanged(data));

}

void AccelerometerReadingChanged(Vector3 data)

{

     this.textBlock1.Text &＃61; "x: " &＃43; data.X.ToString("0.00");

     this.textBlock2.Text &＃61; " y: " &＃43; data.Y.ToString("0.00");

     this.textBlock3.Text &＃61; " z: " &＃43; data.Z.ToString("0.00");

}

 

private void StartAccelerometerEmulation()

{

    var emulationDataAsObservable &＃61; EmulateAccelerometerReading().ToObservable();

    emulationDataAsObservable.Subscribe(args &＃61;> InvokeAccelerometerReadingChanged(args));

}

 

static IEnumerable<Vector3> EmulateAccelerometerReading()

{

    Random random &＃61; new Random();

 

for (double theta &＃61; 0; ; theta &＃43;&＃61; .1)

    {

   

        Vector3 reading &＃61; new Vector3((float)Math.Sin(theta), (float)Math.Cos(theta * 1.1), (float)Math.Sin(theta * .7));

        reading.Normalize();

 

        if (random.NextDouble() > .95)

        {

             reading &＃61; new Vector3((float)(random.NextDouble() * 3.0 - 1.5),

                     (float)(random.NextDouble() * 3.0 - 1.5),

                     (float)(random.NextDouble() * 3.0 - 1.5));

 

         }

 

          yield return reading;

         Thread.Sleep(200);

  }

}

 

 

 

 

模拟Location数据&＃xff1a;

Thread t &＃61; new Thread(StartLocationEmulation);

t.Start();

 

watcher &＃61; new GeoCoordinateWatcher(GeoPositionAccuracy.Default);

watcher.MovementThreshold &＃61; 35;

 

var gcwo &＃61; Observable.FromEvent<GeoPositionChangedEventArgs<GeoCoordinate>>(

eh &＃61;>watcher.PositionChanged &＃43;&＃61;eh,

eh &＃61;>watcher.PositionChanged -&＃61;eh);

 

watcher.Start();

 

private void StartLocationEmulation()

{

     var position &＃61; EmulatePositionChangedEvents().ToObservable();

     position.Subscribe(ev &＃61;> wait_PositionChanged(null, ev));

}

 

static IEnumerable<GeoPositionChangedEventArgs<GeoCoordinate>> EmulatePositionChangedEvents()

{

     Random random &＃61; new Random();

     while (true)

     {

        double latitude &＃61; (random.NextDouble() * 180.0) - 90.0; // latitude is between -90 and 90

        double longitude &＃61; (random.NextDouble() * 360.0) - 180.0; // longitude is between -180 and 180

        yield return new GeoPositionChangedEventArgs<GeoCoordinate>(

        new GeoPosition<GeoCoordinate>(DateTimeOffset.Now, new GeoCoordinate(latitude, longitude)));

 

         Thread.Sleep(random.Next(2000));

       }

}

 

private void wait_PositionChanged(object sender, GeoPositionChangedEventArgs<GeoCoordinate> e)

{

    Deployment.Current.Dispatcher.BeginInvoke(()&＃61;>MyPositionChanged(e));

}

 

private void MyPositionChanged(GeoPositionChangedEventArgs<GeoCoordinate> e)

{

   this.textBlock1.Text &＃61; "Time: " &＃43; e.Position.Timestamp. ToString("yyyy-MM-dd hh:mm:ss");

   this.textBlock2.Text &＃61; "Latitude: " &＃43; e.Position.Location.Latitude.ToString("0.00");

   this.textBlock3.Text &＃61; "Longitude: " &＃43; e.Position.Location.Longitude.ToString("0.00");

}