Windows窗体在.NET 4.0框架WebBrowser控件错误

问题描述

我有我的C＃code，我已经定制形式的网页浏览器，支持浏览器的自动完成功能，抛出一个致命的错误。该异常被抛出只能在.NET 4.0框架，当我们试图获得WebBrowserSite COM接口。

I have a fatal error thrown from my c# code where I have customized forms web browser to support browser autocomplete functionality.The exception gets thrown only on .net 4.0 framework, when we try to obtain the WebBrowserSite COM interfaces.

error thrown at _baseIDocHostUiHandler = (WebBrowserNativeMethods.IDocHostUIHandler)                            Marshal.GetTypedObjectForIUnknown(_unkInnerAggregated,                                                              typeof (WebBrowserNativeMethods.IDocHostUIHandler));

code：

Code:

        // constructor
        public AutoCompleteWebBrowserSite(WebBrowser host) :
            base(host)
        {

            // get the CCW object for this
            _unkOuter = Marshal.GetIUnknownForObject(this);
            Marshal.AddRef(_unkOuter);
            try
            {
                // aggregate the CCW object with the helper Inner object
                _inner = new AutoCompleteHelper(this);
                _unkInnerAggregated = Marshal.CreateAggregatedObject(_unkOuter, _inner);

                // obtain private WebBrowserSite COM interfaces
                try
                {
                    _baseIDocHostUiHandler =                            (WebBrowserNativeMethods.IDocHostUIHandler)                            Marshal.GetTypedObjectForIUnknown(_unkInnerAggregated,                                                              typeof (WebBrowserNativeMethods.IDocHostUIHandler));
                }
                catch(Exception)
            }
            finally
            {
                Marshal.Release(_unkOuter);
            }
        }

有关此异常任何原因及解决办法？这不会发生在机器的框架4.5。

Any reason and solution for this exception? This does not happen on machines with framework 4.5.

推荐答案

基本上需要从构造函数（主要是_baseIDocHostUiHandler）删除所有code

Basically need to remove all the code from constructor (mainly _baseIDocHostUiHandler)

和然后在WebBrowserSite实现中，尝试返回默认实现值的每个的方法。

And then in the WebBrowserSite implementation, try returning the default implementation value for each of the methods.

   private const int DefaultImpVal = unchecked((int)0x80004001)

  #region IDocHostUIHandler
            int WebBrowserNativeMethods.IDocHostUIHandler.ShowContextMenu(int dwId, ref WebBrowserNativeMethods.Point pt, IntPtr pcmdtReserved, IntPtr pdispReserved)
            {
                return DefaultImpVal ;
            }

int WebBrowserNativeMethods.IDocHostUIHandler.ShowUI(int dwId, IntPtr activeObject, IntPtr commandTarget, IntPtr frame, IntPtr doc)
            {
                return DefaultImpVal;
            }

类似地用于其它方法

similarly for other methods.

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