【IT168技术文档】众所周知Silverlight2对于音视频媒体也提供了很好的支持，本篇就音频部分做一个播放器实例。
本例实现的是播放器最基本的功能，大家可通过该例体会一下Silverlight2对音频的控制。
本例参考自《Pro Silverlight 2 in C# 2008》CHAPTER 10 SOUND, VIDEO, AND DEEP ZOOM
XAML Code：
<UserControl x:Class="SilverlightApplication1.Page"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="250" Width="200">
<Grid Margin="20">
<Grid.Background>
<LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
<GradientStop Color="Gold" Offset="0"></GradientStop>
<GradientStop Color="White" Offset="0.5"></GradientStop>
<GradientStop Color="Gold" Offset="1"></GradientStop>
</LinearGradientBrush>
</Grid.Background>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
</Grid.RowDefinitions>
<!--媒体组件-->
<MediaElement x:Name="media" AutoPlay="False" Source="test.mp3"
MediaOpened="media_MediaOpened"
MediaFailed="media_MediaFailed"
MediaEnded="media_MediaEnded"
CurrentStateChanged="media_CurrentStateChanged">
</MediaElement>
<StackPanel Orientation="Horizontal">
<!--播放键-->
<Button Click="cmdPlay_Click" Padding="15" Margin="5">
<StackPanel>
<Polygon Points="0,0 0,10 10,5" Fill="Green"></Polygon>
</StackPanel>
</Button>
<!--停止键-->
<Button Click="cmdStop_Click" Padding="15" Margin="5">
<StackPanel>
<Rectangle Height="10" Width="10" Fill="Red"></Rectangle>
</StackPanel>
</Button>
<!--暂停键-->
<Button Click="cmdPause_Click" Padding="15" Margin="5">
<StackPanel Orientation="Horizontal">
<Rectangle Margin="1" Height="10" Width="3" Fill="Blue"></Rectangle>
<Rectangle Margin="1" Height="10" Width="3" Fill="Blue"></Rectangle>
</StackPanel>
</Button>
</StackPanel>
<Grid Grid.Row="1" Margin="0,10,0,0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"></ColumnDefinition>
<ColumnDefinition></ColumnDefinition>
</Grid.ColumnDefinitions>
<!--音量调节按钮-->
<TextBlock Margin="5" Text="Volume: "></TextBlock>
<Slider x:Name="sliderVolume" Grid.Column="1" Minimum="0" Maximum="1"
Value="0.5" ValueChanged="sliderVolume_ValueChanged"></Slider>
<!--平衡调节按钮-->
<TextBlock Grid.Row="1" Margin="5" Text="Balance: "></TextBlock>
<Slider x:Name="sliderBalance" Grid.Row="1" Grid.Column="1" Minimum="-1"
Maximum="1" ValueChanged="sliderBalance_ValueChanged"></Slider>
<!--播放进度调节按钮-->
<TextBlock Grid.Row="2" Margin="5" Text="Seek To: "></TextBlock>
<Slider x:Name="sliderPosition" Minimum="0" Grid.Column="1" Grid.Row="2"
ValueChanged="sliderPosition_ValueChanged"></Slider>
<!--播放进度条-->
<Slider x:Name="sliderPositionBackground" Minimum="0" Grid.Column="1"
Grid.Row="2" IsHitTestVisible="False" Opacity="0.5">
</Slider>
</Grid>
<!--循环播放选项-->
<CheckBox x:Name="chkLoop" Grid.Row="2" Margin="5,5,5,5" Content="Loop"></CheckBox>
<!--静音选项-->
<CheckBox x:Name="chkMute" Grid.Row="3" Margin="5,0"
Content="Mute" Click="chkMute_Click"></CheckBox>
<!--播放状态提示-->
<TextBlock x:Name="lblStatus" Grid.Row="4" Margin="10"
HorizontalAlignment="Center"></TextBlock>
</Grid>
</UserControl>
C# Code：
using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;
namespace SilverlightApplication1
{
public partial class Page : UserControl
{
public Page()
{
InitializeComponent();
//设置计时器精确度
timer.Interval = TimeSpan.FromSeconds(0.1);
//装载计时器
timer.Tick += timer_Tick;
}
//停止播放
public void mediaStop()
{
//将进度调节按钮与进度条归零
sliderPosition.Value = 0;
sliderPositionBackground.Value = 0;
//停止播放
media.Stop();
timer.Stop();
}
private void timer_Tick(object sender, EventArgs e)
{
lblStatus.Text = media.Position.ToString().TrimEnd(new char[] { '0' });
//使播放进度条跟随播放时间移动
sliderPositionBackground.Value = media.Position.TotalSeconds;
}
//计时器
private DispatcherTimer timer = new DispatcherTimer();
//播放键
private void cmdPlay_Click(object sender, RoutedEventArgs e)
{
//判断播放器是否处于暂停状态
if (sliderPositionBackground.Value != 0)
{
//处于暂停状态则继续播放
media.Position = TimeSpan.FromSeconds(sliderPositionBackground.Value);
media.Play();
timer.Start();
}
else
{
//处于停止状态则开始播放
media.Stop();
media.Play();
timer.Start();
}
}
//暂停键
private void cmdPause_Click(object sender, RoutedEventArgs e)
{
media.Pause();
timer.Stop();
}
//停止键
private void cmdStop_Click(object sender, RoutedEventArgs e)
{
mediaStop();
}
//播放器打开
private void media_MediaOpened(object sender, RoutedEventArgs e)
{
media.Stop();
//将播放进度调节按钮和播放进度条的长度设为音频时长
sliderPosition.Maximum = media.NaturalDuration.TimeSpan.TotalSeconds;
sliderPositionBackground.Maximum = media.NaturalDuration.TimeSpan.TotalSeconds;
}
//播放进度调节按钮
private void sliderPosition_ValueChanged(object sender, RoutedEventArgs e)
{
//使进度条跟随调节按钮移动
sliderPositionBackground.Value = sliderPosition.Value;
//从调节位置播放
media.Stop();
media.Position = TimeSpan.FromSeconds(sliderPosition.Value);
media.Play();
timer.Start();
}
//音量调节按钮
private void sliderVolume_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
if (media != null) media.Volume = sliderVolume.Value;
}
//平衡调节按钮
private void sliderBalance_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
media.Balance = sliderBalance.Value;
}
//静音选项
private void chkMute_Click(object sender, RoutedEventArgs e)
{
media.IsMuted = (bool)chkMute.IsChecked;
}
//获取错误提示
private void media_MediaFailed(object sender, ExceptionRoutedEventArgs e)
{
lblStatus.Text = e.ErrorException.Message;
}
//播放结束
private void media_MediaEnded(object sender, RoutedEventArgs e)
{
//判断是否需要循环播放
if ((bool)chkLoop.IsChecked)
{
//循环播放
media.Position = TimeSpan.Zero;
media.Play();
}
else
{
//停止播放
mediaStop();
}
}
//获取播放状态
private void media_CurrentStateChanged(object sender, RoutedEventArgs e)
{
//在Textblock中显示播放状态
lblStatus.Text = media.CurrentState.ToString();
}
}
}
