wpf 研习1-24小时自学wpf9

events handle

 

routed event:

UIElement(all elements inherits from);bubble(冒泡,up to root element),tunnel(隧道,down from root element);

void Handle_RoutedEvent(object sender, RoutedEventArgs e) RoutedEventArgs derives from EventArgs,includes extra information that WPF uses to work its magic;

 

Properties Specific to RoutedEventArgs

Name	Description
Source	The object that raised the event. This is a property you will generally be interested in. It’s useful to note that with routed events this is likely to be different from the sender.
OriginalSource	This returns original reporting source. That is the object that really raised the event. This property does not change as the event travels along its route.
Handled	A bool that lets you know if the event has already been handled. You should mark this true in your own handlers.
RoutedEvent	This identifies the type of event that was raised. Many events have the same signature, and a single handler might be responsible for several events.

 

通过 e.Handled = true; 显式中止路由链上的二次触发(见 附件1);

 

使用场景

building (or compositing) your own custom controls;

 

attached event(works like attached property)

如

ButtonBase.Click=”StackPanel_Click”

 

常规格式为Type.EventName,Type is the name of the class that owns the event(见 附件2);

 

对TextEditor的再完善

<local:TextEditorToolbar x:Name="toolbar"
                                       DockPanel.Dock="Top"
                                       ComboBox.SelectionChanged="TextEditorToolbar_SelectionChanged" />

 

 

//MainWindow.xaml.cs

private void TextEditorToolbar_SelectionChanged(object sender,SelectionChangedEventArgs e)

{

  //e is a routed event,use OriginalSource to get a reference to the ComboBox

  ComboBox source = e.OriginalSource as ComboBox;

  if (source == null) return;

  switch (source.Name)

  {

    case "fonts”:

    //change the font face break;

    case "fontSize”:

    //change the font size break;

   }

 body.Focus();

 }

 

Action<T>

delegate void Action<T>(T obj); 

 

Preview Events

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;

 

namespace PreviewEvents {

 public partial class Window1

 {

   public Window1()

   {

    InitializeComponent();

    }

   private void Handler(object sender, KeyEventArgs e)

   {

    bool isPreview = e.RoutedEvent.Name.StartsWith("Preview");

    string direction = isPreview ? "v" : "^";

    Output.Items.Add(string.Format("{0} {1}", direction, sender.GetType().Name));

    if (sender == e.OriginalSource && isPreview)

       Output.Items.Add("-{bounce}-");

    if (sender == this && !isPreview)

       Output.Items.Add("-end-");

    }

 }

}

 

详见 附件3;

 

 

小记：

WPF,a set of composite UI elements;

事件,可写代码的外链接;

路由事件,在wpf中获得了超越普通事件的扩展和增强。