稳扎稳打Silverlight(18) - 2.0视频之详解MediaElement, 开发一个简易版的全功能播放器

<UserControl x:Class="Silverlight20.Video.VideoPlayer" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> 
        <StackPanel HorizontalAlignment="Left"> 
         
                <!-- 
                Source - 需要播放的媒体地址 
                Stretch - 拉伸值 [System.Windows.Media.Stretch 枚举]。参见：本Demo的Shape/Shape.xaml 
                AutoPlay - 是否自动播放媒体 
                --> 
                <MediaElement x:Name="mediaElement" 
                                Width="400" Height="200" 
                                Source="http://download.microsoft.com/download/2/0/5/205d8c39-3d55-4032-8195-7b0e6eda4cb6/WinVideo-SL-InstallExperience.wmv"    
                                Stretch="Fill"    
                                AutoPlay="False"> 
                </MediaElement> 

                <Button x:Name="play" Content="播放" Margin="5" Click="play_Click" /> 
                <Button x:Name="pause" Content="暂停" Margin="5" Click="pause_Click" /> 
                <Button x:Name="stop" Content="停止" Margin="5" Click="stop_Click" /> 
                <Button x:Name="mute" Content="静音" Margin="5" Click="mute_Click" /> 

                <Slider x:Name="playSlider" Minimum="0" Maximum="1" Margin="5" ToolTipService.ToolTip="播放进度" ValueChanged="playSlider_ValueChanged" /> 
                <Slider x:Name="volumeSlider" Minimum="0" Maximum="1" Margin="5" ToolTipService.ToolTip="音量大小" ValueChanged="volumeSlider_ValueChanged" /> 
                <Slider x:Name="balanceSlider" Minimum="-1" Maximum="1" Margin="5" ToolTipService.ToolTip="音量平衡" ValueChanged="balanceSlider_ValueChanged" /> 

                <TextBlock x:Name="lblPlayTime" Margin="5" /> 
                <TextBlock x:Name="lblVolume" Margin="5" /> 
                <TextBlock x:Name="lblBalance" Margin="5" /> 

                <TextBlock x:Name="lblDownloadProgress" Margin="5" /> 
                <TextBlock x:Name="lblBufferingProgress" Margin="5" /> 
                <TextBlock x:Name="lblDroppedFramesPerSecond" Margin="5" /> 
                <TextBlock x:Name="lblState" Margin="5" /> 

                <TextBlock x:Name="lblWidth" Margin="5" /> 
                <TextBlock x:Name="lblHeight" Margin="5" /> 
                <TextBlock x:Name="lblTotalTime" Margin="5" /> 
                <TextBlock x:Name="lblBufferingTime" Margin="5" /> 

        </StackPanel> 
</UserControl>

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 System.Windows.Threading; 
 
namespace Silverlight20.Video 
{ 
         public partial  class VideoPlayer : UserControl 
        { 
                 // 媒体的时长 
                 private TimeSpan _duration; 
 
                 private DispatcherTimer _timer =  new DispatcherTimer(); 
 
                 public VideoPlayer() 
                { 
                        InitializeComponent(); 
 
                         this.Loaded +=  new RoutedEventHandler(VideoPlayer_Loaded); 
 
                         /* 
                         * MediaOpened - 当媒体被成功地打开时所触发的事件 
                         * MediaFailed - 当媒体未能被成功地打开时所触发的事件 
                         * CurrentStateChanged - 播放状态（CurrentState）发生改变时所触发的事件 
                         * DownloadProgressChanged - 下载进度（DownloadProgress）发生变化时所触发的事件（当下载增加量大于等于 0.05 或下载进度增加到 1 时会触发此事件） 
                         * MediaEnded - 当媒体播放到末尾时所触发的事件 
                         * BufferingProgressChanged - 缓冲进度（BufferingProgress）发生变化时所触发的事件（当缓冲增加量大于等于 0.05 或缓冲进度增加到 1 时会触发此事件） 
                         */ 
 
                        mediaElement.MediaOpened +=  new RoutedEventHandler(mediaElement_MediaOpened); 
                        mediaElement.CurrentStateChanged +=  new RoutedEventHandler(mediaElement_CurrentStateChanged); 
                        mediaElement.DownloadProgressChanged +=  new RoutedEventHandler(mediaElement_DownloadProgressChanged); 
                        mediaElement.MediaEnded +=  new RoutedEventHandler(mediaElement_MediaEnded); 
                        mediaElement.BufferingProgressChanged +=  new RoutedEventHandler(mediaElement_BufferingProgressChanged); 
                } 
 
                 void VideoPlayer_Loaded( object sender, RoutedEventArgs e) 
                { 
                         // 每 500 毫秒调用一次指定的方法 
                        _timer.Interval = TimeSpan.FromMilliseconds(500); 
                        _timer.Tick +=  new EventHandler(_timer_Tick); 
                        _timer.Start(); 
                } 
 
                 void _timer_Tick( object sender, EventArgs e) 
                { 
                         // CurrentState - 播放状态 [System.Windows.Media.MediaElementState枚举] 
                         // Position - 媒体的位置（单位：秒） 
                         if (mediaElement.CurrentState == MediaElementState.Playing) 
                        { 
                                lblPlayTime.Text =  string.Format( 
                                         "{0}{1:00}:{2:00}:{3:00}", 
                                         "播放进度：", 
                                        mediaElement.Position.Hours, 
                                        mediaElement.Position.Minutes, 
                                        mediaElement.Position.Seconds); 
                        } 
 
                         // DroppedFramesPerSecond - 媒体每秒正在丢弃的帧数 
                        lblDroppedFramesPerSecond.Text =  "每秒正在丢弃的帧数：" + mediaElement.DroppedFramesPerSecond.ToString(); 
                } 
 
                 void mediaElement_BufferingProgressChanged( object sender, RoutedEventArgs e) 
                { 
                         // BufferingProgress - 缓冲进度（0 - 1 之间） 
                        lblBufferingProgress.Text =  string.Format( 
                                 "缓冲进度：{0:##%}", 
                                mediaElement.BufferingProgress); 
                } 
 
                 void mediaElement_MediaEnded( object sender, RoutedEventArgs e) 
                { 
                        mediaElement.Stop(); 
                } 
 
                 void mediaElement_DownloadProgressChanged( object sender, RoutedEventArgs e) 
                { 
                         // DownloadProgress - 下载进度（0 - 1 之间） 
                        lblDownloadProgress.Text =  string.Format( 
                                 "下载进度：{0:##%}", 
                                mediaElement.DownloadProgress); 
                } 
                 private  void mediaElement_MediaOpened( object sender, RoutedEventArgs e) 
                { 
                         /* 
                         * NaturalVideoWidth - 媒体文件的宽 
                         * NaturalVideoHeight - 媒体文件的高 
                         * HasTimeSpan - 是否可取得媒体文件的时长 
                         * NaturalDuration - 媒体文件的时长 
                         * Volume - 音量大小（0 - 1 之间） 
                         * Balance - 音量平衡（-1 - 1 之间） 
                         * BufferingTime - 需要缓冲的时间的长度 
                         */ 
 
                        lblWidth.Text =  "媒体文件的宽：" + mediaElement.NaturalVideoWidth.ToString(); 
                        lblHeight.Text =  "媒体文件的高：" + mediaElement.NaturalVideoHeight.ToString(); 
 
                        _duration = mediaElement.NaturalDuration.HasTimeSpan ? mediaElement.NaturalDuration.TimeSpan : TimeSpan.FromMilliseconds(0); 
 
                        lblTotalTime.Text =  string.Format( 
                                 "{0}{1:00}:{2:00}:{3:00}",  "时长：", 
                                _duration.Hours, 
                                _duration.Minutes, 
                                _duration.Seconds); 
 
                        mediaElement.Volume = 0.8; 
                        volumeSlider.Value = 0.8; 
                        lblVolume.Text =  "音量大小：80%"; 
 
                        mediaElement.Balance = 0; 
                        balanceSlider.Value = 0; 
                        lblBalance.Text =  "音量平衡：0%"; 
 
                        mediaElement.BufferingTime = TimeSpan.FromSeconds(30); 
                        lblBufferingTime.Text =  "缓冲长度：30秒"; 
                } 
 
                 private  void mediaElement_CurrentStateChanged( object sender, RoutedEventArgs e) 
                { 
                         /* 
                         * CurrentState - 播放状态 [System.Windows.Media.MediaElementState枚举] 
                         *         MediaElementState.Closed - 无可用媒体 
                         *         MediaElementState.Opening - 尝试打开媒体（此时Play(),Pause(),Stop()命令会被排进队列，等到媒体被成功打开后再依次执行） 
                         *         MediaElementState.Buffering - 缓冲中 
                         *         MediaElementState.Playing - 播放中 
                         *         MediaElementState.Paused - 被暂停（显示当前帧） 
                         *         MediaElementState.Stopped - 被停止（显示第一帧） 
                         */ 
 
                        lblState.Text =  "播放状态：" + mediaElement.CurrentState.ToString(); 
                } 
 
                 private  void play_Click( object sender, RoutedEventArgs e) 
                { 
                         // Play() - 播放媒体（在当前 Position 处播放） 
                        mediaElement.Play(); 
                } 
 
                 private  void pause_Click( object sender, RoutedEventArgs e) 
                { 
                         // CanPause - 媒体是否可暂停 
                         // Pause() - 暂停媒体的播放 
                         if (mediaElement.CanPause) 
                                mediaElement.Pause(); 
                } 
 
                 private  void stop_Click( object sender, RoutedEventArgs e) 
                { 
                         // Stop() - 停止媒体的播放 
                        mediaElement.Stop(); 
                } 
 
                 void mute_Click( object sender, RoutedEventArgs e) 
                { 
                         // IsMuted - 是否静音 
                         if (mediaElement.IsMuted ==  true) 
                        { 
                                mute.Content =  "静音"; 
                                mediaElement.IsMuted =  false; 
                        } 
                         else 
                        { 
                                mute.Content =  "有声"; 
                                mediaElement.IsMuted =  true; 
                        } 
                } 
 
                 private  void playSlider_ValueChanged( object sender, RoutedPropertyChangedEventArgs< double> e) 
                { 
                         // CanSeek - 是否可以通过设置 Position 来重新定位媒体 
                         // Position - 媒体的位置（单位：秒） 
                         if (mediaElement.CanSeek) 
                        { 
                                mediaElement.Pause(); 
                                mediaElement.Position = TimeSpan.FromSeconds(_duration.TotalSeconds * playSlider.Value); 
                                mediaElement.Play(); 
                        } 
                } 
 
                 private  void volumeSlider_ValueChanged( object sender, RoutedPropertyChangedEventArgs< double> e) 
                { 
                         // Volume - 音量大小（0 - 1 之间） 
                        mediaElement.Volume = volumeSlider.Value; 
                        lblVolume.Text =  string.Format( 
                                 "音量大小：{0:##%}", 
                                volumeSlider.Value); 
                } 
 
                 private  void balanceSlider_ValueChanged( object sender, RoutedPropertyChangedEventArgs< double> e) 
                { 
                         // Balance - 音量平衡（-1 - 1 之间） 
                        mediaElement.Balance = balanceSlider.Value; 
                        lblBalance.Text =  string.Format( 
                                 "音量平衡：{0:##%}", 
                                balanceSlider.Value); 
                } 
        } 
}