稳扎稳打Silverlight(15) - 2.0数据之一次绑定, 单向绑定, 双向绑定, INotifyPropertyChanged, 数据转换

<UserControl x:Class="Silverlight20.Data.NotifyProperty" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> 
        <StackPanel HorizontalAlignment="Left"> 

                <!-- 
                Binding - 将绑定目标对象的属性与数据源联接起来（本例为将 Ellipse的Fill属性 与 MyColor的Brush属性 相联） 
                Mode - Binding 的扩展属性之一，默认为 OneWay（单向绑定），即数据源的改变会自动通知到绑定目标对象的属性 
                --> 
                <Ellipse x:Name="ellipse" Width="100" Height="50" Fill="{Binding Brush, Mode=OneWay}" MouseLeftButtonDown="ellipse_MouseLeftButtonDown" /> 

        </StackPanel> 
</UserControl>

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.ComponentModel; 
 
namespace Silverlight20.Data 
{ 
         public partial  class NotifyProperty : UserControl 
        { 
                MyColor _myColor; 
 
                 public NotifyProperty() 
                { 
                        InitializeComponent(); 
 
                         this.Loaded +=  new RoutedEventHandler(NotifyProperty_Loaded); 
                } 
 
                 void NotifyProperty_Loaded( object sender, RoutedEventArgs e) 
                { 
                        _myColor =  new MyColor { Brush =  new SolidColorBrush(Colors.Red) }; 
 
                         // DataContext - FrameworkElement 做数据绑定时的数据上下文 
                         // 将 MyColor 对象绑定到 Ellipse 
                        ellipse.DataContext = _myColor; 
                } 
 
                 private  void ellipse_MouseLeftButtonDown( object sender, MouseButtonEventArgs e) 
                { 
                         // 鼠标按下后修改 MyColor 对象的属性 
                         // 如果MyColor实现了INotifyPropertyChanged接口，并且绑定目标的BindingMode为OneWay或者TwoWay的话则会自动通知到绑定目标 
                         if (_myColor.Brush.Color == Colors.Red) 
                                _myColor.Brush =  new SolidColorBrush(Colors.Green); 
                         else 
                                _myColor.Brush =  new SolidColorBrush(Colors.Red); 
                } 
        } 
 
         /* 
         * INotifyPropertyChanged - 向客户端发出某一属性值已更改的通知 
         * 使用 OneWay 或者 TwoWay 的话必须要实现 INotifyPropertyChanged 接口 
        */ 
         public  class MyColor : INotifyPropertyChanged 
        { 
                 private SolidColorBrush _brush; 
                 public SolidColorBrush Brush 
                { 
                        get {  return _brush; } 
                        set 
                        { 
                                _brush = value; 
                                 if (PropertyChanged !=  null) 
                                { 
                                         // 触发 PropertyChanged 事件，事件参数为属性名称 
                                        PropertyChanged( this,  new PropertyChangedEventArgs( "Brush")); 
                                } 
                        } 
                } 
 
                 // 声明一个 PropertyChanged 事件 
                 public  event PropertyChangedEventHandler PropertyChanged; 
        } 
}

<!--引用转换器所在的命名空间--> 
<UserControl x:Class="Silverlight20.Data.Conversion" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        xmlns:custom="clr-namespace:Silverlight20.Data"> 
         
        <UserControl.Resources> 
         
                <!--在资源中声明转换器--> 
                <custom:ColorEnumToBrush x:Key="converter" /> 
                 
        </UserControl.Resources> 
         
        <StackPanel HorizontalAlignment="Left"> 

                <!-- 
                Converter - 用于指定转换器 
                ConverterParameter - 转换器所使用的参数 
                ConverterCulture - 转换器所使用的区域信息 
                --> 
                <Ellipse x:Name="ellipse" Width="100" Height="50" MouseLeftButtonDown="ellipse_MouseLeftButtonDown"    
                        Fill="{Binding ColorEnum, Converter={StaticResource converter}, ConverterParameter=10}"    
                /> 

        </StackPanel> 
</UserControl>

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.ComponentModel; 
using System.Windows.Data; 
 
namespace Silverlight20.Data 
{ 
         public partial  class Conversion : UserControl 
        { 
                MyColorEnum _myColorEnum; 
 
                 public Conversion() 
                { 
                        InitializeComponent(); 
 
                         this.Loaded +=  new RoutedEventHandler(Conversion_Loaded); 
                } 
 
                 void Conversion_Loaded( object sender, RoutedEventArgs e) 
                { 
                        _myColorEnum =  new MyColorEnum() { ColorEnum = ColorEnum.Red }; 
 
                         // DataContext - FrameworkElement 做数据绑定时的数据上下文 
                         // 将 MyColorEnum 对象绑定到 Ellipse 
                        ellipse.DataContext = _myColorEnum; 
                } 
 
                 private  void ellipse_MouseLeftButtonDown( object sender, MouseButtonEventArgs e) 
                { 
                         // 鼠标按下后修改 MyColorEnum 对象的属性 
                         if (_myColorEnum.ColorEnum == ColorEnum.Red) 
                                _myColorEnum.ColorEnum = ColorEnum.Green; 
                         else 
                                _myColorEnum.ColorEnum = ColorEnum.Red; 
                } 
        } 
 
         /* 
         * IValueConverter - 值转换接口，将一个类型的值转换为另一个类型的值。它提供了一种将自定义逻辑应用于绑定的方式 
         *         Convert - 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 
         *         ConvertBack - 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 
        */ 
         public  class ColorEnumToBrush : 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</param> 
                 /// <param name="culture">转换器所使用的区域信息</param> 
                 /// <returns>转换后的值</returns> 
                 public  object Convert( object value, Type targetType,  object parameter, System.Globalization.CultureInfo culture) 
                { 
                         // 将 ColorEnum 类型的值转换为 SolidColorBrush 类型的值 
 
                         // parameter == 10 
 
                        ColorEnum color = (ColorEnum)value; 
 
                        SolidColorBrush brush =  new SolidColorBrush(Colors.Red); 
 
                         if (color == ColorEnum.Green) 
                                brush =  new SolidColorBrush(Colors.Green); 
 
                         return brush; 
                } 
 
                 /// <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</param> 
                 /// <param name="culture">转换器所使用的区域信息</param> 
                 /// <returns>转换后的值</returns> 
                 public  object ConvertBack( object value, Type targetType,  object parameter, System.Globalization.CultureInfo culture) 
                { 
                         return  null; 
                } 
        } 
 
         /* 
         * INotifyPropertyChanged - 向客户端发出某一属性值已更改的通知 
         * 使用 OneWay 或者 TwoWay 的话必须要实现 INotifyPropertyChanged 接口 
        */ 
         public  class MyColorEnum : INotifyPropertyChanged 
        { 
                 private ColorEnum _colorEnum; 
                 public ColorEnum ColorEnum 
                { 
                        get {  return _colorEnum; } 
                        set 
                        { 
                                _colorEnum = value; 
                                 if (PropertyChanged !=  null) 
                                { 
                                         // 触发 PropertyChanged 事件，事件参数为属性名称 
                                        PropertyChanged( this,  new PropertyChangedEventArgs( "ColorEnum")); 
                                } 
                        } 
                } 
 
                 // 声明一个 PropertyChanged 事件 
                 public  event PropertyChangedEventHandler PropertyChanged; 
        } 
 
         /// <summary> 
         /// 自定义的 ColorEnum 枚举 
         /// </summary> 
         public  enum ColorEnum 
        { 
                Red, 
                Green 
        } 
}

<!--引用验证类所在的命名空间--> 
<UserControl x:Class="Silverlight20.Data.Validation" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        xmlns:custom="clr-namespace:Silverlight20.Data"> 
         
        <!-- 
        BindingValidationError - 出现验证错误或解决上次验证错误则触发此事件 
        --> 
        <StackPanel HorizontalAlignment="Left" BindingValidationError="StackPanel_BindingValidationError" > 
                 
                <StackPanel.Resources> 
                 
                        <!--在资源中声明验证类--> 
                        <custom:MyValidation x:Name="myValidation"/> 
                         
                </StackPanel.Resources> 
                 
                <TextBox x:Name="textBox" Width="200" Margin="5"> 
                        <TextBox.Text> 
                         
                                <!-- 
                                Binding - 将绑定目标对象的属性与数据源联接起来 
                                        Source - 绑定的数据源 
                                        Mode - 绑定的数据流的方向 [System.Windows.Data.BindingMode枚举] 
                                                BindingMode.OneTime - 一次绑定。创建绑定时一次性地更新绑定目标对象的属性 
                                                BindingMode.OneWay - 单向绑定（默认值）。数据源的改变会自动通知到绑定目标对象的属性 
                                                BindingMode.TwoWay - 双向绑定。数据源或绑定目标对象的属性的值发生改变时会互相通知。显然，做数据验证的话一定要是双向绑定 
                                        Path - 需要绑定的属性名称 
                                        NotifyOnValidationError - 产生验证错误时是否触发 BindingValidationError 事件。默认值为 false 
                                        ValidatesOnExceptions - 产生验证错误时绑定引擎是否要报告错误。默认值为 false 
                                --> 
                                <Binding    
                                        Source="{StaticResource myValidation}"     
                                        Mode="TwoWay"    
                                        Path="Count" 
                                        NotifyOnValidationError="True"    
                                        ValidatesOnExceptions="True" 
                                /> 
                                         
                        </TextBox.Text> 
                </TextBox> 
                 
                <TextBox x:Name="textBox2" Width="200"    Margin="5" /> 
                        
        </StackPanel> 
         
</UserControl>

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.Text.RegularExpressions; 
 
namespace Silverlight20.Data 
{ 
         public partial  class Validation : UserControl 
        { 
                 public Validation() 
                { 
                        InitializeComponent(); 
                } 
 
                 private  void StackPanel_BindingValidationError( object sender, ValidationErrorEventArgs e) 
                { 
                         // ValidationErrorEventArgs - 用于提供 BindingValidationError 事件的一些信息 
                         //         ValidationErrorEventArgs.Action - 验证状态 
                         //         ValidationErrorEventArgs.Error - 触发 BindingValidationError 事件的错误信息 
                         //         ValidationErrorEventArgs.Handled - 标记该路由事件是否已被处理 
                         // ValidationErrorEventAction.Added - 因为出现验证错误而触发此事件 
                         // ValidationErrorEventAction.Removed - 因为解决上次验证错误而触发此事件 
 
                         if (e.Action == ValidationErrorEventAction.Added) 
                        { 
                                textBox.Background =  new SolidColorBrush(Colors.Red); 
                                textBox.Text = e.Error.Exception.Message; 
                        } 
                         else  if (e.Action == ValidationErrorEventAction.Removed) 
                        { 
                                textBox.Background =  new SolidColorBrush(Colors.White); 
                        } 
                } 
        } 
 
         /// <summary> 
         /// 验证类。验证是否为正整数 
         /// </summary> 
         public  class MyValidation 
        { 
                 private  string _count; 
                 public  string Count 
                { 
                        get {  return _count; } 
                        set 
                        { 
                                 if (!Regex.IsMatch(value,  @"^\d+$")) 
                                { 
                                         // 绑定引擎可以报告由属性的 setter 抛出的异常，也可以报告由转换器（IValueConverter）抛出的异常 
                                         throw  new Exception( "必须是正整数"); 
                                } 
 
                                _count = value; 
                        } 
                } 
        } 
}