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.

答

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.

Windows窗体在.NET 4.0框架WebBrowser控件错误

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