本节讲诉两个新特性：一、在Silverlight 5中可以控制MediaElement对象播放的视频进行快进快退控制。二、在Silverlight 5中的文字项进行搜索查询。
一、对于MediaElement媒体播放对象的视频进行快退快进控制
它是通过MediaElement.PlaybackRate属性进行控制的。当前此属性只支持-8.0、-4.0、0.5、1.0、2.0、4.0、8.0七个参数，也就是快退8倍速、快退4倍速、慢放0.5倍速、正常速度、快进2倍速、快进4倍速、快进8倍速。现在我们看本实例中的MediaElement对象控制源码如下：
// 控制播放速度
int flag = 0 ;
private void button6_Click( object sender, RoutedEventArgs e)
{
if (flag == 0 )
{
this .showVideo.PlaybackRate = 0.5 ;
}
else if (flag == 1 )
{
this .showVideo.PlaybackRate = 1.0 ;
}
else if (flag == 2 )
{
this .showVideo.PlaybackRate = 2.0 ;
}
else if (flag == 3 )
{
this .showVideo.PlaybackRate = 4.0 ;
}
else if (flag == 4 )
{
this .showVideo.PlaybackRate = 8.0 ;
flag = 0 ;
return ;
}
flag ++ ;
}
其效果预览图如下：
二、TextSearch对象对文字项查询
它是在Silverlight 5中新增的一个类TextSearch,在所有的具有Item属性的文字控件中（比如ComboBox,ListBox）设置TextSearch.TextPath="FirstName"即可。当然FirstName是被绑定源类的一个字段。下面我们来看XAML源码如下：
<ListBox ItemsSource=
"{Binding}"
TextSearch.TextPath=
"FirstName"
Width=
"176"
Height=
"363"
HorizontalAlignment=
"Center"
VerticalAlignment=
"Center"
DisplayMemberPath=
"FirstName"
Margin=
"610,31,214,106"
/>
<ComboBox ItemsSource=
"{Binding}"
TextSearch.TextPath=
"FirstName"
Width=
"137"
Height=
"30"
HorizontalAlignment=
"Center"
VerticalAlignment=
"Center"
DisplayMemberPath=
"FirstName"
Margin=
"797,31,66,439"
/>
|
在cs代码中需要如下绑定：
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
BindListData();
private void BindListData()
{
DataContext = new List < User > ()
{
new User()
{
FirstName = " liusan " ,
Age = 20
},
new User()
{
FirstName = " liyun " ,
Age = 20
},
new User()
{
FirstName = " liulin " ,
Age = 20
},
new User()
{
FirstName = " mingtian " ,
Age = 20
},
new User()
{
FirstName = " jintian " ,
Age = 20
},
new User()
{
FirstName = " shanghai " ,
Age = 20
},
new User()
{
FirstName = " chengdu " ,
Age = 20
},
new User()
{
FirstName = " luntai " ,
Age = 20
},
new User()
{
FirstName = " shenming " ,
Age = 20
},
new User()
{
FirstName = " edison " ,
Age = 20
},
new User()
{
FirstName = " jeson " ,
Age = 20
},
new User()
{
FirstName = " jiufen " ,
Age = 20
},
new User()
{
FirstName = " jiuding " ,
Age = 20
},
new User()
{
FirstName = " shenfenzheng " ,
Age = 20
}
}.OrderBy(x => x.FirstName);
}
}
public class User
{
public String FirstName
{
get ;
set ;
}
public Int32 Age
{
get ;
set ;
}
}
最后我们在ComboBox或者ListItem取得焦点的时候在键盘上敲英文字符即可自动查找对焦到相应的Item项。本实例采用VS2010+Silverlight 5 beta编写，如需源码请点击 SLTextSearch.zip 下载，现在我们来看运行效果图如下：
本文转自程兴亮博客园博客，原文链接：http://www.cnblogs.com/chengxingliang/archive/2011/04/26/2028455.html，如需转载请自行联系原作者
