巧用Delegate在SilverLight多个页面、控件中传递回调方法

    在论坛中看到经常有人碰到如何在SilverLight多个页面或者控件中传替参数或者值的问题，今天抽空通过Delegate机制实现回调实例方法重设动画参数的DEMO,分享给大家。最终结果如图:

    演示地址:http://xingjunli.webs.com/DelegateDemo.html
    参考资料:动画概述：http://msdn.microsoft.com/zh-cn/library/cc189019(VS.95).aspx 委托：http://msdn.microsoft.com/zh-cn/library/900fyy8e.aspx
   1、初识委托:
      委托delegate有点类似于非托管C/C++中的函数指针，在C#中通过委托机制来回掉实例方法，静态方法等（更重要是委托为托管代码，能保证回调方法的类型的安全）
   2、使用委托回调实例方法:  
      2.1、用C#的delegate关键字来定义回掉函数的签名(本示例中我们通过一个单独的类来实义委托以提高重用):
 /// <summary> /// 声明delegate方法 /// </summary> /// <param name="x"></param> /// <param name="y"></param> public delegate void delgateResetParentMethod(double x,double y);  
     2.2、在子窗体类中我们定义一个委托类型对象如:
 public helper.delgateResetParentMethod CallBackMethod; 
     2.3、在父窗体中实例化子窗体时将实例方法传递给委托:
  UCDelegateChildWindow childWindow = new UCDelegateChildWindow(); childWindow.CallBackMethod = ReaplayAnimation;

     2.4、用我们熟悉的方法调用语法来调用回掉函数:
if (this.DialogResult.Value && CallBackMethod != null) { this.CallBackMethod(Double.Parse(txtX.Text), Double.Parse(txtY.Text)); this.Close(); }

     3、上面我们应用委托实现了最简单的应用，实际工作中会复杂的多；我们的编译器和CLR为我们做了大量幕后工作以减轻使用的复杂性;如需了解更多请参考:委托（C# 编程指南）http://msdn.microsoft.com/zh-cn/library/ms173171.aspx
   实现步骤(附源代码):
     声明委托类型：

public class helper{ /// <summary> /// 声明delegate方法 /// </summary> /// <param name="x"></param> /// <param name="y"></param> public delegate void delgateResetParentMethod(double x,double y);} 
    子窗体XAML：

<controls:ChildWindow x:Class="LoadSilverlight.UCDelegateChildWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:controls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls" Width="200" Height="170" Title="重设动画坐标:"> <Grid x:Name="LayoutRoot" Margin="2"> <Grid.RowDefinitions> <RowDefinition /> <RowDefinition Height="Auto" /> </Grid.RowDefinitions> <Canvas Grid.Row="0" Grid.Column="0" Margin="1"> <Canvas.Background> <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0"> <GradientStop Color="#E6E0F3F4" Offset="0"/> <GradientStop Color="#FFB3BDC7" Offset="1"/> </LinearGradientBrush> </Canvas.Background> <TextBlock Text="X:" Canvas.Left="11" Canvas.Top="8" /> <TextBox x:Name="txtX" Canvas.Left="28" Canvas.Top="8" Width="140" Text="100" /> <TextBlock Text="Y:" Canvas.Left="12" Canvas.Top="46" RenderTransformOrigin="0.417,1.375" /> <TextBox x:Name="txtY" Canvas.Left="28" Canvas.Top="44" Width="140" Text="100"/> </Canvas> <Button x:Name="CancelButton" Content="Cancel" Click="CancelButton_Click" Width="75" Height="23" HorizontalAlignment="Right" Margin="0,12,0,0" Grid.Row="1" /> <Button x:Name="OKButton" Content="OK" Click="OKButton_Click" Width="75" Height="23" HorizontalAlignment="Right" Margin="0,12,79,0" Grid.Row="1" /> </Grid></controls:ChildWindow> 
    子窗体CS:

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;namespace LoadSilverlight{ public partial class UCDelegateChildWindow : ChildWindow { public UCDelegateChildWindow() { InitializeComponent(); } private void OKButton_Click(object sender, RoutedEventArgs e) { this.DialogResult = true; if (this.DialogResult.Value && CallBackMethod != null) { this.CallBackMethod(Double.Parse(txtX.Text), Double.Parse(txtY.Text)); this.Close(); } } private void CancelButton_Click(object sender, RoutedEventArgs e) { this.DialogResult = false; } //定义页面委托对象 public helper.delgateResetParentMethod CallBackMethod; }} 
    父窗体XAML:

<UserControl x:Class="LoadSilverlight.UCDelegateParent" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Background="#FF333333" Foreground="{x:Null}"><UserControl.Resources><Storyboard x:Name="sbRun"><DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="ellipse" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.X)"><EasingDoubleKeyFrame KeyTime="00:00:00" Value="0"/><EasingDoubleKeyFrame KeyTime="00:00:06" Value="200"><EasingDoubleKeyFrame.EasingFunction><ElasticEase EasingMode="EaseOut"/></EasingDoubleKeyFrame.EasingFunction></EasingDoubleKeyFrame></DoubleAnimationUsingKeyFrames><DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="ellipse" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.Y)"><EasingDoubleKeyFrame KeyTime="00:00:00" Value="0"/><EasingDoubleKeyFrame KeyTime="00:00:06" Value="200"><EasingDoubleKeyFrame.EasingFunction><ElasticEase EasingMode="EaseOut"/></EasingDoubleKeyFrame.EasingFunction></EasingDoubleKeyFrame></DoubleAnimationUsingKeyFrames></Storyboard></UserControl.Resources> <Grid x:Name="LayoutRoot" Background="#FF424242"> <Ellipse x:Name="ellipse" Height="64" HorizontalAlignment="Left" Margin="25,32,0,0" VerticalAlignment="Top" Width="64" RenderTransformOrigin="0.5,0.5"> <Ellipse.RenderTransform> <TransformGroup> <ScaleTransform/> <SkewTransform/> <RotateTransform/> <TranslateTransform x:Name="ellipseTrans"/> </TransformGroup> </Ellipse.RenderTransform> <Ellipse.Fill> <RadialGradientBrush RadiusX="0.559" RadiusY="0.559"> <GradientStop Color="#FFFF0606"/> <GradientStop Color="#72702525" Offset="0.717"/> <GradientStop Color="#00702525" Offset="1"/> </RadialGradientBrush> </Ellipse.Fill> </Ellipse> <Button x:Name="btnReset" Height="33" HorizontalAlignment="Right" Margin="0,0,8,8" VerticalAlignment="Bottom" Width="100" Content="重设坐标" FontFamily="微软雅黑" FontWeight="Bold" FontSize="18.667"/> <HyperlinkButton HorizontalAlignment="Right" Margin="8,0,116,15" VerticalAlignment="Bottom" Content="http://Blog.csdn.net/xingjunli" NavigateUri="http://Blog.csdn.net/xingjunli" FontStyle="Italic"/> </Grid></UserControl> 
    父窗体CS:

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;namespace LoadSilverlight{ public partial class UCDelegateParent : UserControl { UCDelegateChildWindow childWindow; public UCDelegateParent() { InitializeComponent(); btnReset.Click += new RoutedEventHandler(btnReset_Click); sbRun.Completed += new EventHandler(sbRun_Completed); this.Loaded += new RoutedEventHandler(UCDelegateParent_Loaded); } void UCDelegateParent_Loaded(object sender, RoutedEventArgs e) { sbRun.Begin(); } void sbRun_Completed(object sender, EventArgs e) { ShowChildWindow(); } void btnReset_Click(object sender, RoutedEventArgs e) { ShowChildWindow(); } private void ShowChildWindow() { if (childWindow == null) { childWindow = new UCDelegateChildWindow(); childWindow.CallBackMethod = ReaplayAnimation; //为子窗体(可以是任意窗体或者控件)注册父窗体实例方法(这里的参数类型和个数必须匹配) } childWindow.Show(); } //父窗体重设动画属性播放动画 private void ReaplayAnimation(double x,double y) { DoubleAnimationUsingKeyFrames framsX = sbRun.Children[0] as DoubleAnimationUsingKeyFrames; DoubleAnimationUsingKeyFrames framsY = sbRun.Children[1] as DoubleAnimationUsingKeyFrames; framsX.KeyFrames[0].Value = framsX.KeyFrames[1].Value; framsX.KeyFrames[1].Value = x; framsY.KeyFrames[0].Value = framsY.KeyFrames[1].Value; framsY.KeyFrames[1].Value = y; sbRun.Stop(); sbRun.Begin(); } }} 
  结束语:SilverLight同.Net FrameWork本身已经很好的结合起来，C#中一些实用的编程机制(如：委托)，在SL中合理运用，将给我们带来意想不到的收获!