在 C# 中挂钩 IE 事件

Question

我正在尝试从现有 IE window 捕获事件。在下面的代码示例中，我试图在用户单击某个元素时在浏览器文档中捕获 mouseClick 事件，然后最终拉回有关被单击元素的一些属性。

public partial class frmBrowserElementBuilder : Form
{
    InternetExplorer ie;
    public frmBrowserElementBuilder()
    {
        InitializeComponent();
    }

    private void frmBrowserElementBuilder_Load(object sender, EventArgs e)
    {
        //create IE
        ie = new InternetExplorer();
        ie.Visible = true;

        //handle document completed
        ie.DocumentComplete += new
      DWebBrowserEvents2_DocumentCompleteEventHandler(DocumentComplete);

    }

    public void DocumentComplete(object pDisp, ref object URL)
    {
        //document was loaded
        //MessageBox.Show("DocumentComplete: " + URL);

        //create event handler and hook onclick from IE
        DHTMLEventHandler onClickHandler = new DHTMLEventHandler(ie.Document);
        onClickHandler.assignedEvent += new DHTMLEvent(this.ie_onClick);
        ie.Document.onclick = onClickHandler;
    }

    private void ie_onClick(mshtml.IHTMLEventObj e)
    {
        //something was clicked
        MessageBox.Show(string.Format("Event Hooked {0}, Qualifier {1}", e.type, e.qualifier));
    }

    public delegate void DHTMLEvent(IHTMLEventObj e);

    [ComVisible(true)]
    public class DHTMLEventHandler
    {
        public DHTMLEvent assignedEvent;

        private mshtml.HTMLDocument document;
        public DHTMLEventHandler(mshtml.HTMLDocument doc)
        {
            //assign to instance of IE document
            this.document = doc;
        }

        [DispId(0)]
        public void Call()
        {
            //call the event
            assignedEvent(this.document.parentWindow.@event); //{System.InvalidCastException: "Specified cast is not valid."}
        }

    }

}

代码编译并且 void Call() 按预期触发，但是，this.document.parentwindow 的值为 null 并抛出 System.InvalidCastException: Specified cast is not valid when stepping into the assignedEvent method.

当我检查 this.document 时，parentWindow 的值表示

The function evaluation requires all threads to run.

在强制求值后它指出：

'((mshtml.HTMLDocumentClass)this.document).parentWindow' threw an exception of type 'System.InvalidCastException'.

有什么想法吗？

Answer 1

这是一个 threading 问题。 Call() 调用发生在 MTA 线程上，您不能从 MTA 线程访问 MSHTML。有很多方法可以改变这一点，但是，最简单的是这样做：

public void DocumentComplete(object pDisp, ref object URL)
{
    var events = (HTMLDocumentEvents2_Event)ie.Document;
    events.onclick += (evt) =>
    {
        MessageBox.Show(string.Format("Event Hooked {0}, Qualifier {1}", evt.type, evt.qualifier));
        return false;
    };
}

在 C# 中挂钩 IE 事件

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