上篇介绍了用C++调用JavaScript，这篇反过来说说JS调C++，这样JS和C++沟通的途径就完整了。
首先，实现一个IDispatch接口，当JS调用C++函数时，系统会调用GetIDsOfNames来用函数名取得函数的DISPID，然后调用Invoke完成真正的调用，需要注意的是Invoke的pDispParams中的参数是倒序的。代码如下：
class CExtenalDispatch : public IDispatch
{
public:
CExtenalDispatch()
{
m_dwRef = 0;
}
~CExtenalDispatch()
{
}
STDMETHOD_(ULONG, AddRef)()
{
return InterlockedIncrement(&m_dwRef);
}
STDMETHOD_(ULONG, Release)()
{
unsigned long l = InterlockedDecrement(&m_dwRef);
if(l == 0)
delete this;
return l;
}
STDMETHOD(QueryInterface)(REFIID iid, LPVOID far* ppvObject)
{
HRESULT hrRet = S_OK;
*ppvObject = NULL;
if(IsEqualIID(iid, IID_IDispatch))
*ppvObject = (IDispatch*)this;
else
hrRet = E_NOINTERFACE;
if (S_OK == hrRet)
((IUnknown*)*ppvObject)->AddRef();
return hrRet;
}
STDMETHOD(GetTypeInfoCount)(UINT* pctinfo)
{
return E_NOTIMPL;
}
STDMETHOD(GetTypeInfo)(/* [in] */ UINT iTInfo,
/* [in] */ LCID lcid,
/* [out] */ ITypeInfo** ppTInfo)
{
return E_NOTIMPL;
}
STDMETHOD(GetIDsOfNames)(
/* [in] */ REFIID riid,
/* [size_is][in] */ LPOLESTR *rgszNames,
/* [in] */ UINT cNames,
/* [in] */ LCID lcid,
/* [size_is][out] */ DISPID *rgDispId)
{
HRESULT hr = S_OK;
for (int i = 0; i < (int)cNames; i++)
{
CString cszName = rgszNames[i];
if(cszName == L"myfunction")
{
bFind = TRUE;
rgDispId[i] = 1;
break;
}
else
{
// One or more are unknown so set the return code accordingly
hr = ResultfromScode(DISP_E_UNKNOWNNAME);
rgDispId[i] = DISPID_UNKNOWN;
}
}
return hr;
}
STDMETHOD(Invoke)(
/* [in] */ DISPID dispIdMember,
/* [in] */ REFIID riid,
/* [in] */ LCID lcid,
/* [in] */ WORD wFlags,
/* [out][in] */ DISPPARAMS *pDispParams,
/* [out] */ VARIANT *pVarResult,
/* [out] */ EXCEPINFO
1. oncontextmenu="window.event.returnValue=false" 将彻底屏蔽鼠标右键
<table border oncontextmenu=return(false)> <td>no </table> 可用于Table
2. <body onselectstart="return false"> 取消选取、防止复制
3. onpaste="return false" 不准粘贴
4. oncopy="return false;" onc ......
