如何访问丢失/隐藏的 HTMLDocumentEvents4 事件（onchange 事件）或将事件侦听器附加到元素

Question

在 MSHTML 界面中的 HTMLDocumentEvents4 应该包含大约 30 个事件 （根据msdn页面http://msdn.microsoft.com/en-us/library/ff976251(v=vs.85).aspx#events） 但只有 onmssitemodejumplistitemremoved 和 onmsthumbnailclick 可用我想访问其他事件..尤其是更改事件.. 如何访问那些其他事件

using System.Runtime.InteropServices;
namespace MSHTML
{
 [ComVisible(false)]
 [TypeLibType(TypeLibTypeFlags.FHidden)]
 public interface HTMLDocumentEvents4_Event
 {
     event HTMLDocumentEvents4_onmssitemodejumplistitemremovedEventHandler onmssitemodejumplistitemremoved;
     event HTMLDocumentEvents4_onmsthumbnailclickEventHandler onmsthumbnailclick;
 }
}

在我的代码中，我尝试如下访问，但它不起作用（未分配侦听器）

//Event handler class
public delegate void DHTMLEvent(IHTMLEventObj e);

[ComVisible(true)]
public class DHTMLEventHandler
{

    public DHTMLEvent Handler;
    HTMLDocument Document;

    public DHTMLEventHandler(HTMLDocument doc)
    {
        this.Document = doc;
    }
    [DispId(0)]
    public void Call()
    {
        Handler(Document.parentWindow.@event);
    }


}

    //My code
        HTMLDocumentEvents2_Event Events = (HTMLDocumentEvents2_Event)document;
        Events.onclick += new HTMLDocumentEvents2_onclickEventHandler(Events_onclick);//working

         HTMLDocumentEvents4_Event Events2 = (HTMLDocumentEvents4_Event)document;
    //   Events2.change ->Not availabe so  as a workaround I did the below but that is also not      //     working

        DHTMLEventHandler onchangeHandler = new DHTMLEventHandler(document);
        onchangeHandler.Handler += new DHTMLEvent(Events_onchange);
        document.attachEvent("onchange", onchangeHandler);  //Not working
        document.onchange = onchangeHandler;                //Not Working

     private void Events_onchange(IHTMLEventObj e)
    {
        //I want to do my operation here but this is not called as listener is not assigned
    }

     private Boolean Events_onclick(IHTMLEventObj e)
    {
      //working perfectly 
     }

所以我想通过自定义方法或使用 HTMLDocumentEvents4 接口的隐藏事件来监听 onchange 事件..帮帮我

Answer 1

我得到了一个解决方法，如何将事件侦听器附加到元素
1.创建 HTMLHandlerClass 用于将事件处理程序附加到元素
2.从文档中获取所有元素或要为其附加监听器的元素
3.cast元素为IHTMLElement2
4.通过调用 element.attachEvent

附加事件监听器 第 1 步

using MSHTML;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Text;

namespace IEToolbarEngine
{
class HtmlHandler : IReflect
{
    public HtmlHandler(EventHandler evHandler, IHTMLWindow2 sourceWindow)
    {
        this.eventHandler = evHandler;
        this.htmlWindow = sourceWindow;
    }

    public IHTMLWindow2 SourceHTMLWindow
    {
        get { return this.htmlWindow; }
    }

    #region IReflect

    FieldInfo IReflect.GetField(string name, BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetField(name, bindingAttr);
    }

    FieldInfo[] IReflect.GetFields(BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetFields(bindingAttr);
    }

    MemberInfo[] IReflect.GetMember(string name, BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetMember(name, bindingAttr);
    }

    MemberInfo[] IReflect.GetMembers(BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetMembers(bindingAttr);
    }

    MethodInfo IReflect.GetMethod(string name, BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetMethod(name, bindingAttr);
    }

    MethodInfo IReflect.GetMethod(string name, BindingFlags bindingAttr, Binder binder, Type[] types, ParameterModifier[] modifiers)
    {
        return this.typeIReflectImplementation.GetMethod(name, bindingAttr, binder, types, modifiers);
    }

    MethodInfo[] IReflect.GetMethods(BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetMethods(bindingAttr);
    }

    PropertyInfo[] IReflect.GetProperties(BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetProperties(bindingAttr);
    }

    PropertyInfo IReflect.GetProperty(string name, BindingFlags bindingAttr)
    {
        return this.typeIReflectImplementation.GetProperty(name, bindingAttr);
    }

    PropertyInfo IReflect.GetProperty(string name, BindingFlags bindingAttr, Binder binder, Type returnType, Type[] types, ParameterModifier[] modifiers)
    {
        return this.typeIReflectImplementation.GetProperty(name, bindingAttr, binder, returnType, types, modifiers);
    }

    object IReflect.InvokeMember(string name, BindingFlags invokeAttr, Binder binder, object target, object[] args, ParameterModifier[] modifiers, CultureInfo culture, string[] namedParameters)
    {
        if (name == "[DISPID=0]")
        {
            if (this.eventHandler != null)
            {
                this.eventHandler(this, EventArgs.Empty);
            }
        }

        return null;
    }

    Type IReflect.UnderlyingSystemType
    {
        get
        {
            return this.typeIReflectImplementation.UnderlyingSystemType;
        }
    }

    #endregion


    private IReflect typeIReflectImplementation = typeof(HtmlHandler);
    private EventHandler eventHandler;
    private IHTMLWindow2 htmlWindow;
}
}

第 2 步
在这里，我获取了所有输入元素，因为我想附加 onchange 事件侦听器

 private void attachOnChangeEvent(HTMLDocument doc, Boolean flag)
    {
        // Install onchange for <input type=password, text, file>.

        IHTMLElementCollection inputElementList = doc.getElementsByTagName("input");
        foreach (IHTMLElement el in inputElementList)
        {
            String inputType = el.getAttribute("type") as String;
            if (("text" == inputType) || ("password" == inputType) || ("file" == inputType))
            {
                IHTMLElement2 inputElement = el as IHTMLElement2;
                IHTMLWindow2 wnd = (el.document as IHTMLDocument2).parentWindow;
                inputElement.attachEvent("onchange", new HtmlHandler(onchangeInput, wnd));

            }

        }
   }


  private void onchangeInput(object sender, EventArgs e)
    {
        HtmlHandler htmlHandler = (HtmlHandler)sender;
        IHTMLElement element = htmlHandler.SourceHTMLWindow.@event.srcElement;

      //Do whatever i want with the element

    }