重新想象 Windows 8 Store Apps (52)

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重新想象 Windows 8 Store Apps (52) - 绑定: 与 Element Model Indexer Style RelativeSource 绑定, 以及绑定中的数据转换

作者：webabcd


介绍
重新想象 Windows 8 Store Apps 之 绑定

• 与 Element 绑定
• 与 Model 绑定
• 与 Indexer 绑定
• 对 Style 中的 Setter 进行绑定（绑定静态资源）
• Binding 的一个扩展标记 RelativeSource 的应用
• 绑定中的数据转换

示例
1、演示如何与 Element 绑定，以及 OneTime, OneWay, TwoWay 的区别
Binding/BindingElement.xaml

<Page
    x:Class="XamlDemo.Binding.BindingElement"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Binding"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0">
           
            <!--
                本例用于演示如何与 Element 绑定，以及 OneTime, OneWay, TwoWay 的区别
            -->
            
            <!--
                OneTime 方式绑定元素
            -->
            <Slider Name="sliderOneTime" Minimum="1" Maximum="100" Value="10" Width="180" HorizontalAlignment="Left" />
            <TextBox Text="{Binding ElementName=sliderOneTime, Path=Value, Mode=OneTime}" Width="150" HorizontalAlignment="Left" />

            <!--
                OneWay 方式绑定元素（OneWay 是默认方式）
            -->
            <Slider Name="sliderOneWay" Minimum="1" Maximum="100" Value="10" Width="180" HorizontalAlignment="Left" Margin="0 50 0 0" />
            <TextBox Text="{Binding ElementName=sliderOneWay, Path=Value, Mode=OneWay}" Width="150" HorizontalAlignment="Left" />

            <!--
                TwoWay 方式绑定元素
            -->
            <Slider Name="sliderTwoWay" Minimum="1" Maximum="100" Value="10" Width="180" HorizontalAlignment="Left" Margin="0 50 0 0" />
            <TextBox Text="{Binding ElementName=sliderTwoWay, Path=Value, Mode=TwoWay}" Width="150" HorizontalAlignment="Left" />

        </StackPanel>
    </Grid>
</Page>

2、演示如何与 Model 进行双向绑定
Binding/BindingModel.xaml

<Page
    x:Class="XamlDemo.Binding.BindingModel"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Binding"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0" Name="root">
            
            <TextBlock Name="lblMsg" FontSize="14.667" />
            
            <TextBox FontSize="14.667" Text="{Binding Path=Name, Mode=TwoWay}" Margin="0 10 10 0" />
            <TextBox FontSize="14.667" Text="{Binding Age, Mode=TwoWay}" Margin="0 10 10 0" />
            <ToggleSwitch OffContent="女" OnContent="男" Header="性别" Margin="0 10 10 0">
                <ToggleSwitch.IsOn>
                    <Binding Path="IsMale" Mode="TwoWay" />
                </ToggleSwitch.IsOn>
            </ToggleSwitch>
            
        </StackPanel>
    </Grid>
</Page>

Binding/BindingModel.xaml.cs

/*
 * 演示如何与 Model 进行双向绑定
 */

using System;
using System.ComponentModel;
using Windows.System.Threading;
using Windows.UI.Core;
using Windows.UI.Xaml.Controls;
using XamlDemo.Model;

namespace XamlDemo.Binding
{
    public sealed partial class BindingModel : Page
    {
        private Employee _employee;

        public BindingModel()
        {
            this.InitializeComponent();

            this.Loaded += BindingModel_Loaded;
        }

        void BindingModel_Loaded(object sender, Windows.UI.Xaml.RoutedEventArgs e)
        {
            // 创建一个需要绑定的实体对象（注：Employee 实现了 INotifyPropertyChanged 接口，想要 OneWay 或者 TwoWay 的话必须要实现 INotifyPropertyChanged 接口）
            _employee = new Employee();
            _employee.Name = "webabcd";
            _employee.Age = 33;
            _employee.IsMale = true;

            // 每 5 秒更新一次数据
            ThreadPoolTimer.CreatePeriodicTimer(
                (timer) =>
                {
                    var ignored = Dispatcher.RunAsync(CoreDispatcherPriority.High,
                        () =>
                        {
                            Random random = new Random();
                            _employee.Age = random.Next(10, 100);
                            _employee.IsMale = random.Next() % 2 == 0 ? true : false;
                        });
                },
                TimeSpan.FromMilliseconds(5000));

            // Employee 对象的属性的值发生变化时触发的事件
            _employee.PropertyChanged += _employee_PropertyChanged;

            root.DataContext = _employee;
        }

        // 每次属性的值发生变化时，显示变化后的结果
        void _employee_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            lblMsg.Text = "属性：“" + e.PropertyName + "”的值发生了变化";
            lblMsg.Text += Environment.NewLine;
            lblMsg.Text += string.Format("当前的值为：Name-{0}, Age-{1}, IsMale-{2}", _employee.Name, _employee.Age, _employee.IsMale);
        }
    }
}

3、演示如何与索引器进行绑定
Binding/BindingIndexer.xaml

<Page
    x:Class="XamlDemo.Binding.BindingIndexer"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Binding"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0">

            <!--演示如何绑定集合中的某个元素-->
            <TextBlock Name="textBlock" FontSize="14.667" Text="{Binding Path=[3] }" />

            <!--示如何绑定集合中的某个对象的某个属性-->
            <TextBlock Name="textBlock2" FontSize="14.667" Text="{Binding Path=[5].Name }" Margin="0 10 0 0" />

            <!--演示如何绑定 string 类型的索引器-->
            <TextBlock Name="textBlock3" FontSize="14.667" Text="{Binding Path=[webabcd] }" Margin="0 10 0 0" />

            <!--演示如何绑定字典表中指定 key 的数据-->
            <TextBlock Name="textBlock4" FontSize="14.667" Text="{Binding Path=[hello] }" Margin="0 10 0 0" />

        </StackPanel>
    </Grid>
</Page>

Binding/BindingIndexer.xaml.cs

/*
 * 演示如何与索引器进行绑定
 */

using System.Collections.Generic;
using Windows.UI.Xaml.Controls;
using XamlDemo.Model;

namespace XamlDemo.Binding
{
    public sealed partial class BindingIndexer : Page
    {
        public BindingIndexer()
        {
            this.InitializeComponent();

            this.Loaded += BindingIndexer_Loaded;
        }

        void BindingIndexer_Loaded(object sender, Windows.UI.Xaml.RoutedEventArgs e)
        {
            // 用于演示如何绑定集合中的某个元素
            List<string> list = new List<string>();
            for (int i = 0; i < 10; i++)
            {
                list.Add("索引：" + i.ToString());
            }
            textBlock.DataContext = list;

            // 用于演示如何绑定集合中的某个对象的某个属性
            textBlock2.DataContext = TestData.GetEmployees();

            // 用于演示如何绑定 string 类型的索引器
            textBlock3.DataContext = this;

            // 用于演示如何绑定字典表中指定 key 的数据
            Dictionary<string, string> dic = new Dictionary<string, string>();
            dic["hello"] = "hello webabcd";
            textBlock4.DataContext = dic;
        }

        // 自定义一个索引器
        public object this[string indexer]
        {
            get
            {
                return indexer;
            }
        }
    }
}

4、演示 Style 中的 Setter 如何做数据绑定（绑定静态资源）
Binding/BindingStyleSetter.xaml

<Page
    x:Class="XamlDemo.Binding.BindingStyleSetter"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Binding"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0">

            <!--
                演示 Style 中的 Setter 如何做数据绑定
            -->
            
            <StackPanel.Resources>
                <!--设置一些资源-->
                <x:Double x:Key="TextFontSize">24.667</x:Double>
                <SolidColorBrush x:Key="TextForeground" Color="#00FF00" />

                <!--为 Style 的 Setter 的 Value 做数据绑定-->
                <Style x:Key="MyStyle" TargetType="TextBox">
                    <Setter Property="FontSize" Value="{Binding Source={StaticResource TextFontSize}}"/>
                    <Setter Property="Foreground" Value="{Binding Source={StaticResource TextForeground}}"/>
                </Style>
            </StackPanel.Resources>

            <!--应用样式-->
            <TextBox Text="我是TextBox" Style="{StaticResource MyStyle}" />

        </StackPanel>
    </Grid>
</Page>

5、演示 Binding 中的一个扩展标记 RelativeSource 的应用
Binding/BindingRelativeSource.xaml

<Page
    x:Class="XamlDemo.Binding.BindingRelativeSource"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Binding"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0">

            <!--
                演示 Binding 中的一个扩展标记 RelativeSource 的应用，其用于指定关联数据源为 Self 或 TemplatedParent
                另外简要说明 TemplateBinding 的应用
            -->
            
            <StackPanel.Resources>
                <Style x:Key="MyStyle" TargetType="Button">
                    <Setter Property="Template">
                        <Setter.Value>
                            <ControlTemplate TargetType="Button">
                                <StackPanel>
                                    <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="White" />
                                    <!--
                                        TemplateBinding 是一个简单版的 Binding，用于在模板中绑定控件的某个属性
                                    
                                        如果设计模板时需要用到双向绑定，则 TemplateBinding 就无能为力了（TemplateBinding 是 OneWay 的）
                                        只能通过 Binding 来做双向绑定，然后通过 RelativeSource={RelativeSource TemplatedParent} 指定数据源来自引用了该 ControlTemplate 的 Control
                                    -->
                                    <Slider Minimum="1" Maximum="100" Width="{TemplateBinding Width}" Value="{Binding Content, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" />
                                </StackPanel>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </StackPanel.Resources>

            <Button Width="300" Content="10" Style="{StaticResource MyStyle}" />

            
            <!--
                RelativeSource={RelativeSource Self} - 指定数据源为自己本身
            -->
            <TextBlock Text="{Binding RelativeSource={RelativeSource Self}, Path=Tag}" Tag="webabcd" FontSize="14.667" Margin="0 10 0 0" />

        </StackPanel>
    </Grid>
</Page>

6、演示如何在绑定中做数据转换
Binding/IntegerLetterConverter.cs

/*
 * 继承 IValueConverter 以实现一个“整数-字母”转换器
 */

using System;
using Windows.UI.Xaml.Data;

namespace XamlDemo.Binding
{
    public sealed class IntegerLetterConverter : IValueConverter
    {
        /// <summary>
        /// 正向转换器。将值从数据源传给绑定目标时，数据绑定引擎会调用此方法
        /// </summary>
        /// <param name="value">转换之前的值</param>
        /// <param name="targetType">转换之后的类型</param>
        /// <param name="parameter">转换器所使用的参数（它是通过 Binding 的 ConverterParameter 传递过来的）</param>
        /// <param name="language">转换器所使用的区域信息（它是通过 Binding 的 ConverterLanguage 传递过来的）</param>
        /// <returns>转换后的值</returns>
        public object Convert(object value, Type targetType, object parameter, string language)
        {
            if ((double)value == 1)
                return "a";
            else if ((double)value == 2)
                return "b";
            else if ((double)value == 3)
                return "c";
            else
                return "unknown";
        }

        /// <summary>
        /// 反向转换器。将值从绑定目标传给数据源时，数据绑定引擎会调用此方法
        /// </summary>
        /// <param name="value">转换之前的值</param>
        /// <param name="targetType">转换之后的类型</param>
        /// <param name="parameter">转换器所使用的参数（它是通过 Binding 的 ConverterParameter 传递过来的）</param>
        /// <param name="language">转换器所使用的区域信息（它是通过 Binding 的 ConverterLanguage 传递过来的）</param>
        /// <returns>转换后的值</returns>
        public object ConvertBack(object value, Type targetType, object parameter, string language)
        {
            if ((string)value == "a")
                return 1;
            else if ((string)value == "b")
                return 2;
            else if ((string)value == "c")
                return 3;
            else
                return 1;
        }
    }
}

Binding/ValueConverter.xaml

<Page
    x:Class="XamlDemo.Binding.ValueConverter"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Binding"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0">

            <!--配置 IValueConverter 资源-->
            <StackPanel.Resources>
                <local:IntegerLetterConverter x:Key="IntegerLetterConverter"/>
            </StackPanel.Resources>

            <Slider Name="slider" Minimum="1" Maximum="3" Value="1" Width="180" HorizontalAlignment="Left" />
            <TextBox Width="150" HorizontalAlignment="Left"
                     Text="{Binding Value, 
                                    Mode=TwoWay, 
                                    ElementName=slider, 
                                    Converter={StaticResource IntegerLetterConverter},
                                    ConverterParameter=param, 
                                    ConverterLanguage=zh_cn}" />

            <!--注：ConverterParameter 和 ConverterLanguage 不能实现动态的绑定，只能传递静态的参数-->

        </StackPanel>
    </Grid>
</Page>

OK
[源码下载]