Windows phone 應用開發[5]-FrameworkDispatcher異常處理

當你在Silverlight 或是Windows phone 應用程序中經過引用Microsoft.Xan.Framework嘗試經過後臺任務播放一段音頻文件或是記錄音頻時. 一般會遇到以下關於FrameworkDispatcher異常信息:

一旦嘗試在後臺任務記錄或播放一段音頻文件.老是提示Application沒有調用FrameworkDisplatcher.Update()方法.當你使用XNA對象在一個Silverlight或Windows phone 應用程序時這個異常很正常.在執行播聽任務前.因首先檢查在後臺是否已經存在該資源任務的佔用.若是已經佔用.則以對話框的形式來提示用戶是否中止.Check Code:

if (!Microsoft.Xna.Framework.Media.MediaPlayer.GameHasControl)
//play Background Music File

在XnaFramework中 Xna框架的事件消息處理機制是放在一個XNA處理的消息隊列中.在一個XNa Application 中實現GAme類. FrameworkDispatcher.Update()方法是自動調用Game.Update處理.

在一個沒有實現GAme類的Windows phone或Silverlight應用程序中.則必須採用手動的方式調用FrameWorkDisplatcher.Update()經過XnaFrameWork消息隊列本身發送消息.

Well 首先添加引用:

using System.Windows.Threading;
using Microsoft.Xna.Framework;

建立一個類實現IApplicationService接口:

public partial class NuanceFunctionDemo_Form : RecognizerListener, IApplicationService
{}

實現接口兩個方法:

public void StartService(ApplicationServiceContext context)
{
_frameworkDispatcherTimer.Start();
}

public void StopService()
{
_frameworkDispatcherTimer.Stop();
}

而接口調用_frameworkDispatcherTimer則是DispatcherTimer對象的實例.完整處理Code:

private DispatcherTimer _frameworkDispatcherTimer;

void NuanceFunctionDemo_Form_Loaded(object sender, RoutedEventArgs e)
{
    this.VoiceType_LP.ItemsSource = voiceDefineTypeList;
    this.VoiceType_LP.SelectedIndex = 0;

    //textBoxResult.Text = "test one. test two. test three. test four.";
    textBoxServerIp.Text = AppInfo.SpeechKitServer;
    textBoxServerPort.Text = AppInfo.SpeechKitPort.ToString();


    _frameworkDispatcherTimer = new DispatcherTimer();
    _frameworkDispatcherTimer.Tick += FrameworkDispatcherTimer_Tick;
    _frameworkDispatcherTimer.Interval = new TimeSpan(0, 0, 3);
    FrameworkDispatcher.Update();
    speechkitInitialize();
    App.CancelSpeechKit += new CancelSpeechKitEventHandler(App_CancelSpeechKit);
}


public void StartService(ApplicationServiceContext context)
{
    _frameworkDispatcherTimer.Start();
}

public void StopService()
{
    _frameworkDispatcherTimer.Stop();
}

void FrameworkDispatcherTimer_Tick(object sender, EventArgs e)
{
    FrameworkDispatcher.Update();
}
}

這個異常在Silverlight和Windows phone 是常見的異常. 關於frameworkDispatcher處理方式 請參考MSDN用法.

參考資料:

Enable Xna Framework Events in Windows phone Application