Winows Phone 7 不温不火学习之《音乐播放示例》

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> 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.Xna.Framework;
using Microsoft.Xna.Framework.Media;
using System.Windows.Threading;
using System.IO;
using System.Windows.Resources;
using System.Windows.Media.Imaging;


namespace PostCodeManager
{
public partial class MainPage:PhoneApplicationPage
{
#region 成员声明
Song_playSong; // 声明一个Song类型的变量
bool _historyItemLaunch;
const String_playSongKey = " playSong " ;
#endregion


// Constructor
public MainPage()
{
InitializeComponent();
_playSong = null ;
_historyItemLaunch = false ;

// 声明一个Timer使用线程运行XNAinternals来自于微软XNA框架
DispatcherTimerdt = new DispatcherTimer();
dt.Interval = TimeSpan.FromMilliseconds( 33 );
// 使用委托调用逐帧调用FrameworkDispatcher.Update();
dt.Tick += delegate
{
try
{
// 这个函数作用是更新各种XNA组件状态，并触发相应的事件,这个是必须的，否则会报异常
FrameworkDispatcher.Update();

}
catch
{

throw ;
}
};
dt.Start();

MediaPlayer.MediaStateChanged += new EventHandler < EventArgs > (MediaPlayer_MediaStateChanged);

}

/// <summary>
/// 当页面进入时调用
/// </summary>
/// <paramname="e"></param>
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgse)
{
MediaLibrarylibrary = new MediaLibrary();
if (NavigationContext.QueryString.ContainsKey(_playSongKey))
{
StringsongToPlay = NavigationContext.QueryString[_playSongKey];
foreach (Songsong in library.Songs)
{
if ( 0 == String.Compare(songToPlay,song.Name))
{
_playSong = song;
}
}
_historyItemLaunch = true ;
}
else if (MediaPlayer.State == MediaState.Playing)
{
_playSong = MediaPlayer.Queue.ActiveSong;
}
else
{
Randomrd = new Random();
if (library.Songs.Count > 0 )
{
_playSong = library.Songs[rd.Next(library.Songs.Count)];
}
else
{
SongName.Text = " nosongsinlibrary " ;
btn_play_music.IsEnabled = false ;
}
}


base .OnNavigatedTo(e);
}

void MediaPlayer_MediaStateChanged( object sender,EventArgse)
{
switch (MediaPlayer.State)
{

case MediaState.Playing:
btn_play_music.IsEnabled = false ;
btn_stop.IsEnabled = true ;
break ;
case MediaState.Paused:
case MediaState.Stopped:
btn_play_music.IsEnabled = true ;
btn_stop.IsEnabled = false ;
break ;
}
}

/// <summary>
/// 为主窗体添加UI加载完成后的事件
/// </summary>
/// <paramname="sender"></param>
/// <paramname="e"></param>
private void PhoneApplicationPage_Loaded( object sender,RoutedEventArgse)
{
PopulateSongMetaData();
setInitialButtonState();
if (_historyItemLaunch)
{
playSong();
}
}


/// <summary>
/// 开始播放音乐
/// </summary>
/// <paramname="sender"></param>
/// <paramname="e"></param>
private void btn_play_music_Click( object sender,RoutedEventArgse)
{
playSong();
}

/// <summary>
/// 停止播放音乐
/// </summary>
/// <paramname="sender"></param>
/// <paramname="e"></param>
private void btn_stop_Click( object sender,RoutedEventArgse)
{
stopSong();
}

/// <summary>
/// 播放
/// </summary>
private void playSong()
{
if (_playSong != null )
{
MediaPlayer.Play(_playSong);
}
}
/// <summary>
/// 停止
/// </summary>
private void stopSong()
{
if (MediaState.Playing == MediaPlayer.State)
{
MediaPlayer.Stop();
}
}

/// <summary>
/// 使用图片读取图片封面
/// </summary>
private void PopulateSongMetaData()
{
if (_playSong != null )
{
SongName.Text = _playSong.Name;
StreamalbumArtStream = _playSong.Album.GetAlbumArt();
if (albumArtStream == null )
{
StreamResourceInfoalbumArtPlaceholder = Application.GetResourceStream( new Uri( " ApplicationIcon.png " ,UriKind.Relative));
albumArtStream = albumArtPlaceholder.Stream;
}
BitmapImagealbumArtImage = new BitmapImage();
albumArtImage.SetSource(albumArtStream);
cover.Source = albumArtImage;
}
}

/// <summary>
/// 初始化按钮
/// </summary>
private void setInitialButtonState()
{
switch (MediaPlayer.State)
{

case MediaState.Playing:
btn_play_music.IsEnabled = false ;
btn_stop.IsEnabled = true ;
break ;
case MediaState.Paused:
case MediaState.Stopped:
btn_play_music.IsEnabled = true ;
btn_stop.IsEnabled = false ;
break ;
}
}



}
}