Silverlight 5 beta新特性探索系列:9.视频快进快退和TextSearch对象对文字项查询

        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:

posted @ 2011-04-26 10:18  程兴亮  阅读(2155)  评论(1编辑  收藏