巧用Delegate在SilverLight多个页面、控件中传递回调方法

概述    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/l

    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" GrID.Row="1" /> <button x:name="OKbutton" Content="OK" Click="OKbutton_Click" WIDth="75" Height="23" HorizontalAlignment="Right" margin="0,79,0" 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" 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="0,8,8" VerticalAlignment="Bottom" WIDth="100" Content="重设坐标" FontFamily="微软雅黑" FontWeight="Bold" FontSize="18.667"/> <Hyperlinkbutton HorizontalAlignment="Right" margin="8,116,15" 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!

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