稳扎稳打Silverlight(50) - 4.0绑定之DependencyObject绑定, 索引器绑定, StringFormat, TargetNullV

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稳扎稳打Silverlight(50) - 4.0绑定之DependencyObject绑定, 索引器绑定, StringFormat, TargetNullValue和FallbackValue, CollectionViewSource

作者：webabcd


介绍
Silverlight 4.0 绑定相关的增强：

• DependencyObject Binding - 新增了对 DependencyObject 绑定的支持 
• Indexer Binding - 新增了对索引器绑定的支持 
• StringFormat - 指定绑定数据的显示格式 
• TargetNullValue - 当绑定数据为 null 时所需要显示的值 
• FallbackValue - 当绑定失败（无法返回值）的时候所需要显示的值 
• CollectionViewSource - 实现了 ICollectionView 的类，可以通过它对数据排序、筛选和分组 

在线DEMO
http://www.cnblogs.com/webabcd/archive/2010/08/09/1795417.html


示例
1、演示如何绑定到 DependencyObject
DependencyObjectBinding.xaml
代码 <navigation:Page x:Class="Silverlight40.Binding.DependencyObjectBinding" 
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
           xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
           Title="DependencyObjectBinding Page">
    <Grid x:Name="LayoutRoot">
        <StackPanel HorizontalAlignment="Left">

            <!-- 
                Silverlight 3.0 支持绑定到 FrameworkElement 
                    TextBox 继承自 FrameworkElement
            -->
            <TextBox Text="{Binding ElementName=slider, Path=Value}" />

            <!-- 
                Silverlight 4.0 中新增了对 DependencyObject 绑定的支持
                    RotateTransform 继承自 DependencyObject
            -->
            <Rectangle Width="100" Height="100" RenderTransformOrigin="0.5, 0.5" Fill="Red">
                <Rectangle.RenderTransform>
                    <RotateTransform Angle="{Binding ElementName=slider, Path=Value}" />
                </Rectangle.RenderTransform>
            </Rectangle >

            <Slider Name="slider" Height="20" Minimum="0" Maximum="360" />

        </StackPanel>
    </Grid>
</navigation:Page>


2、演示如何绑定到索引器
IndexerBinding.xaml 代码 <navigation:Page x:Class="Silverlight40.Binding.IndexerBinding" 
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
           xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
           Title="IndexerBinding Page">
    <Grid x:Name="LayoutRoot">

        <!--
            用于演示索引器的绑定
        -->
        <TextBlock Name="textBlock" Text="{Binding Path=[3] }" />

    </Grid>
</navigation:Page>

IndexerBinding.xaml.cs 代码 /*
 * Silverlight 4.0 中新增了对索引器绑定的支持，索引的类型必须实现 IList
 */

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.Navigation;

namespace Silverlight40.Binding
{
    public partial class IndexerBinding : Page
    {
        public IndexerBinding()
        {
            InitializeComponent();
        }

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            List<string> list = new List<string>();
            for (int i = 0; i < 10; i++)
            {
                list.Add("索引：" + i.ToString());
            }

            textBlock.DataContext = list;
        }
    }
}


3、演示在绑定时使用 StringFormat 来指定数据的显示格式
StringFormat.xaml 代码 <navigation:Page x:Class="Silverlight40.Binding.StringFormat" 
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
           xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
           Title="StringFormat Page">
    <Grid x:Name="LayoutRoot">

        <!--
            StringFormat - 指定绑定数据的显示格式
        -->
        <TextBlock Name="textBlock" Text="{Binding StringFormat='yyyy-MM-dd HH:mm:ss'}" />
        
    </Grid>
</navigation:Page>

StringFormat.xaml.cs
代码 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.Navigation;

namespace Silverlight40.Binding
{
    public partial class StringFormat : Page
    {
        public StringFormat()
        {
            InitializeComponent();
        }

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            textBlock.DataContext = DateTime.Now;
        }
    }
}


4、演示 TargetNullValue 和 FallbackValue 的效果
TargetNullValueFallbackValue.xaml 代码 <navigation:Page x:Class="Silverlight40.Binding.TargetNullValueFallbackValue" 
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
           xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
           Title="TargetNullValueFallbackValue Page">
    <Grid x:Name="LayoutRoot">
        <StackPanel HorizontalAlignment="Left" Name="stackPanel">

            <!--
                FallbackValue - 当绑定失败（无法返回值）的时候所需要显示的值
            -->
            <TextBlock Text="{Binding Path=xxx, FallbackValue='绑定失败时的默认值'}" />

            <!--
                TargetNullValue - 当绑定数据为 null 时所需要显示的值
            -->
            <TextBlock Text="{Binding TargetNullValue='绑定返回值为 null'}" />

        </StackPanel>
    </Grid>
</navigation:Page>

TargetNullValueFallbackValue.xaml.cs 代码 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.Navigation;

namespace Silverlight40.Binding
{
    public partial class TargetNullValueFallbackValue : Page
    {
        public TargetNullValueFallbackValue()
        {
            InitializeComponent();
        }

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            stackPanel.DataContext = null;
        }
    }
}


5、演示 CollectionViewSource 的应用
Product.cs 代码 using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace Silverlight40.Binding
{
    // 实体类
    public class Product
    {
        public int ProductId { get; set; }
        public string Name { get; set; }
        public string Category { get; set; }
    }
}

ProductCollection.cs 代码 using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using System.Collections.Generic;

namespace Silverlight40.Binding
{
    public class ProductCollection : List<Product>
    {
        
    }
}

CollectionViewSource.xaml 代码 <navigation:Page x:Class="Silverlight40.Binding.CollectionViewSource" 
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
           xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
           xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
           xmlns:c="clr-namespace:System.ComponentModel;assembly=System.Windows"
           xmlns:local="clr-namespace:Silverlight40.Binding"
           Title="CollectionViewSource Page">
    <Grid x:Name="LayoutRoot">

        <Grid.Resources>
            <local:ProductCollection x:Key="products">
                <local:Product ProductId="1" Name="abc" Category="CategoryA" />
                <local:Product ProductId="2" Name="xyz" Category="CategoryA" />
                <local:Product ProductId="3" Name="webabcd" Category="CategoryB" />
            </local:ProductCollection>

            <!--
                CollectionViewSource - 实现了 ICollectionView 的类，可以通过它对数据排序、筛选和分组
                    CollectionViewSource.SortDescriptions - 指定排序方式
                        PropertyName - 指定排序的字段
                        Direction - 指定按升序还是降序排序
                    CollectionViewSource.GroupDescriptions - 指定分组方式
                        PropertyName - 指定分组的字段
                        StringComparison - 指定是否区分大小写等
            -->
            <CollectionViewSource x:Name="dataSource" Source="{StaticResource products}">
                <CollectionViewSource.SortDescriptions>
                    <c:SortDescription PropertyName="Name" Direction="Descending" />
                </CollectionViewSource.SortDescriptions>
                <CollectionViewSource.GroupDescriptions>
                    <PropertyGroupDescription PropertyName="Category" StringComparison="CurrentCultureIgnoreCase" />
                </CollectionViewSource.GroupDescriptions>
            </CollectionViewSource>
        </Grid.Resources>

        <sdk:DataGrid ItemsSource="{Binding Source={StaticResource dataSource}}" />

    </Grid>
</navigation:Page>


OK
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