在silverlight实际项目中时常会需要播放视频和打印文档，在本节中我们将制作一个最简单的播放视频和打印文档的实例。

一、播放WMV视频

首先我们创建一个Silverlight应用程序SLShowVideo，然后放一个示例Wmv视频在SLShowVideo.web项目的根目录下面。

然后我们在Xaml文档中放入一个MediaElement控件，并写入以下代码：

<MediaElement Height="377" HorizontalAlignment="Left" Margin="8,31,0,0"
 Name="showVideo" VerticalAlignment="Top" Width="583" />
<Button Content="播 放" Height="28" HorizontalAlignment="Left" Margin="194,428,0,0"
 Name="button1" VerticalAlignment="Top" Width="99" Click="button1_Click_1" />
<Button Content="暂 停" Height="28" HorizontalAlignment="Left" Margin="333,428,0,0"
 Name="button3" VerticalAlignment="Top" Width="99" Click="button3_Click" />
<Button Content="停 止" Height="28" HorizontalAlignment="Left" Margin="468,428,0,0"
 Name="button2" VerticalAlignment="Top" Width="99" Click="button2_Click" />
<Button Content="加载视频" Height="28" HorizontalAlignment="Left" Margin="57,428,0,0"
 Name="button4" VerticalAlignment="Top" Width="99" Click="button1_Click"/>

最后我们写入以下代码加载视频并且控制视频的播放：

#region 播放视频
private void button1_Click(object sender, RoutedEventArgs e)
{
 //加载视频
 this.showVideo.Source = new Uri(GetURL()+"/sampleVideo.wmv");
}
/// <summary>
/// 获取当前网站的Url前缀
/// </summary>
/// <returns></returns>
public static string GetURL()
{
 ScriptObject location = (HtmlPage.Window.GetProperty("location") as ScriptObject);
 object r = location.GetProperty("href");
 string URL = r.ToString().Substring(0, r.ToString().LastIndexOf('/'));
 //截取到当前SILVERLIGHT程序存放网络URL的前缀
 return URL;
}
private void button3_Click(object sender, RoutedEventArgs e)
{
 //暂停
 this.showVideo.Pause();
}

private void button2_Click(object sender, RoutedEventArgs e)
{
 //停止
 this.showVideo.Stop();
}

private void button1_Click_1(object sender, RoutedEventArgs e)
{
 //播放
 this.showVideo.Play();
}
#endregion

二、打印文档

首先我们看XAML文档。添加一个Canvas元素，元素内的所有内容就是我们即将要打印（当然你也可以设置打印Grid等元素的内容）。

<Canvas Height="376" HorizontalAlignment="Left" Margin="611,32,0,0" Name="canvas1"
 VerticalAlignment="Top" Width="369" >
 <sdk:Label Width="85" Canvas.Left="9" Content="第一个打印程序" Canvas.Top="27" />
 <sdk:Label Canvas.Left="11" Canvas.Top="60" Height="16" Content="第二个打印程序"
 Name="label1" Width="86" />
</Canvas>
<Button Content="打印" Height="34" HorizontalAlignment="Left" Margin="747,426,0,0"
 Name="btnPrint" VerticalAlignment="Top" Width="110" Click="btnPrint_Click" />

在Button事件处理程序中我们添加一下代码打印Canvas元素。

#region 打印文档
PrintDocument print;
private void btnPrint_Click(object sender, RoutedEventArgs e)
{
 print = new PrintDocument();
 //添加一个打印页面事件以设置需要打印的控件
 print.PrintPage += new EventHandler<PrintPageEventArgs>(print_PrintPage);
 print.Print("canvas1");
}

void print_PrintPage(object sender, PrintPageEventArgs e)
{
 //设置打印this.canvas1的所有内容
 e.PageVisual = this.canvas1;
}
#endregion

本实例采用VS2010+Silverlight 4.0编写。如需源码请点击 SLShowVideo.zip 下载。期待Silverlight 5 beta的到来。下面我们看实例的效果图：