JavaScript调用C++函数

 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：

[cpp] view plaincopyprint?

1. class CExtenalDispatch : public IDispatch  
2. {  
3. public:  
4.     CExtenalDispatch()  
5.     {  
6.         m_dwRef = 0;  
7.     }  
8.   
9.     ~CExtenalDispatch()  
10.     {  
11.   
12.     }  
13.       
14.     STDMETHOD_(ULONG, AddRef)()  
15.     {  
16.         return InterlockedIncrement(&m_dwRef);  
17.     }  
18.   
19.     STDMETHOD_(ULONG, Release)()  
20.     {  
21.         unsigned long l = InterlockedDecrement(&m_dwRef);  
22.         if(l == 0)  
23.             delete this;  
24.         return l;  
25.     }  
26.   
27.     STDMETHOD(QueryInterface)(REFIID iid, LPVOID far* ppvObject)  
28.     {  
29.         HRESULT hrRet = S_OK;  
30.         *ppvObject = NULL;  
31.         if(IsEqualIID(iid, IID_IDispatch))  
32.             *ppvObject = (IDispatch*)this;  
33.         else  
34.             hrRet = E_NOINTERFACE;  
35.         if (S_OK == hrRet)  
36.             ((IUnknown*)*ppvObject)->AddRef();  
37.         return hrRet;  
38.     }  
39.   
40.     STDMETHOD(GetTypeInfoCount)(UINT* pctinfo)  
41.     {  
42.         return E_NOTIMPL;  
43.     }  
44.   
45.     STDMETHOD(GetTypeInfo)(/* [in] */ UINT iTInfo,  
46.         /* [in] */ LCID lcid,  
47.         /* [out] */ ITypeInfo** ppTInfo)  
48.     {  
49.         return E_NOTIMPL;  
50.     }  
51.   
52.     STDMETHOD(GetIDsOfNames)(  
53.         /* [in] */ REFIID riid,  
54.         /* [size_is][in] */ LPOLESTR *rgszNames,  
55.         /* [in] */ UINT cNames,  
56.         /* [in] */ LCID lcid,  
57.         /* [size_is][out] */ DISPID *rgDispId)  
58.     {  
59.         HRESULT hr = S_OK;  
60.         for (int i = 0; i < (int)cNames; i++)   
61.         {  
62.             CString cszName = rgszNames[i];  
63.             if(cszName == L"myfunction")  
64.             {  
65.                 bFind = TRUE;  
66.                 rgDispId[i] = 1;  
67.                 break;  
68.             }  
69.             else  
70.             {  
71.                 // One or more are unknown so set the return code accordingly  
72.                 hr = ResultFromScode(DISP_E_UNKNOWNNAME);  
73.                 rgDispId[i] = DISPID_UNKNOWN;  
74.             }  
75.   
76.         }  
77.         return hr;  
78.   
79.     }  
80.       
81.     STDMETHOD(Invoke)(  
82.         /* [in] */ DISPID dispIdMember,  
83.         /* [in] */ REFIID riid,  
84.         /* [in] */ LCID lcid,  
85.         /* [in] */ WORD wFlags,  
86.         /* [out][in] */ DISPPARAMS  *pDispParams,  
87.         /* [out] */ VARIANT  *pVarResult,  
88.         /* [out] */ EXCEPINFO *pExcepInfo,  
89.         /* [out] */ UINT *puArgErr)  
90.     {  
91.         if (!pDispParams)  
92.             return E_INVALIDARG;  
93.   
94.         if(wFlags & DISPATCH_METHOD)  
95.         {  
96.             int memberCount = sizeof(mapMember) / sizeof(MemberInfo);  
97.             switch(dispIdMember)  
98.             {  
99.             case 1:  
100.                 {  
101.                     MessageBox(L"Hello JS!", L"");  
102.                     return S_OK;  
103.                 }  
104.                 break;  
105.             default:  
106.                 return DISP_E_MEMBERNOTFOUND;  
107.                 break;  
108.             }  
109.         }  
110.         return DISP_E_MEMBERNOTFOUND;  
111.     }  
112. private:  
113.     long            m_dwRef;  
114. };  

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;elsehrRet = 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 accordinglyhr = 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 *pExcepInfo,/* [out] */ UINT *puArgErr){if (!pDispParams)return E_INVALIDARG;if(wFlags & DISPATCH_METHOD){int memberCount = sizeof(mapMember) / sizeof(MemberInfo);switch(dispIdMember){case 1:{MessageBox(L"Hello JS!", L"");return S_OK;}break;default:return DISP_E_MEMBERNOTFOUND;break;}}return DISP_E_MEMBERNOTFOUND;}private:longm_dwRef;};

其次，实现一个IDocHostUIHandlerDispatch接口。其中最重要的是GetExternal，它返回一个CExtenalDispatch指针。

[cpp] view plaincopyprint?

1. class CBrowserHostUIHandlerImpl : public IDispatchImpl<IDocHostUIHandlerDispatch, &IID_IDocHostUIHandlerDispatch, &LIBID_ATLLib>  
2. {  
3. public:  
4.     CBrowserHostUIHandlerImpl()  
5.     {  
6.         m_dwRef = 0;  
7.         m_pDispatch = NULL;  
8.     }  
9.   
10.     ~CBrowserHostUIHandlerImpl()  
11.     {  
12.         if(m_pDispatch)  
13.         {  
14.             m_pDispatch->Release();  
15.             m_pDispatch = NULL;  
16.         }  
17.     }  
18.   
19.     STDMETHOD_(ULONG, AddRef)(){ return InterlockedIncrement(&m_dwRef); }  
20.     STDMETHOD_(ULONG, Release)()  
21.     {  
22.         unsigned long l = InterlockedDecrement(&m_dwRef);  
23.         if(l == 0)  
24.             delete this;  
25.         return l;  
26.     }  
27.     STDMETHOD(QueryInterface)(REFIID iid, LPVOID far* ppvObject)  
28.     {  
29.         HRESULT hrRet = S_OK;  
30.         *ppvObject = NULL;  
31.         if (IsEqualIID(iid, IID_IUnknown))  
32.             *ppvObject = (IUnknown*)this;  
33.         else if(IsEqualIID(iid, IID_IDispatch))  
34.             *ppvObject = (IDispatch*)this;  
35.         else if (IsEqualIID(iid, __uuidof(IDocHostUIHandler)))  
36.             *ppvObject = (IDocHostUIHandler*)this;  
37.         else  
38.             hrRet = E_NOINTERFACE;  
39.         if (S_OK == hrRet)  
40.             ((IUnknown*)*ppvObject)->AddRef();  
41.         return hrRet;  
42.     }  
43.     STDMETHOD(ShowContextMenu)(/* [in] */ DWORD dwID,  
44.         /* [in] */ DWORD x,  
45.         /* [in] */ DWORD y,  
46.         /* [in] */ IUnknown *pcmdtReserved,  
47.         /* [in] */ IDispatch *pdispReserved,  
48.         /* [retval][out] */ HRESULT *dwRetVal)  
49.     {  
50.         *dwRetVal = S_OK;  
51.         return S_OK;  
52.     }  
53.       
54.     STDMETHOD(GetHostInfo)(/* [out][in] */ DWORD *pdwFlags, /* [out][in] */ DWORD *pdwDoubleClick)  
55.     {  
56.         *pdwFlags = DOCHOSTUIFLAG_DIV_BLOCKDEFAULT | DOCHOSTUIFLAG_CODEPAGELINKEDFONTS | DOCHOSTUIFLAG_THEME | DOCHOSTUIFLAG_SCROLL_NO | DOCHOSTUIFLAG_NO3DBORDER;  
57.         *pdwDoubleClick = DOCHOSTUIDBLCLK_DEFAULT;  
58.         return S_OK;  
59.     }  
60.   
61.     STDMETHOD(ShowUI)(/* [in] */ DWORD dwID,  
62.         /* [in] */ IUnknown *pActiveObject,  
63.         /* [in] */ IUnknown *pCommandTarget,  
64.         /* [in] */ IUnknown *pFrame,  
65.         /* [in] */ IUnknown *pDoc,  
66.         /* [retval][out] */ HRESULT *dwRetVal)  
67.     {  
68.         return S_OK;  
69.     }  
70.       
71.     STDMETHOD(HideUI)(){ return S_OK; }  
72.     STDMETHOD(UpdateUI)(){ return S_OK; }  
73.     STDMETHOD(EnableModeless)(/* [in] */ VARIANT_BOOL fEnable){ return S_OK; }  
74.     STDMETHOD(OnDocWindowActivate)(/* [in] */ VARIANT_BOOL fActivate){ return S_OK; }  
75.     STDMETHOD(OnFrameWindowActivate)(/* [in] */ VARIANT_BOOL fActivate){ return S_OK; }  
76.     STDMETHOD(ResizeBorder)(/* [in] */ long left,  
77.         /* [in] */ long top,  
78.         /* [in] */ long right,  
79.         /* [in] */ long bottom,  
80.         /* [in] */ IUnknown *pUIWindow,  
81.         /* [in] */ VARIANT_BOOL fFrameWindow)  
82.     {  
83.         return S_OK;  
84.     }  
85.   
86.     STDMETHOD(TranslateAccelerator)(/* [in] */ DWORD_PTR hWnd,  
87.         /* [in] */ DWORD nMessage,  
88.         /* [in] */ DWORD_PTR wParam,  
89.         /* [in] */ DWORD_PTR lParam,  
90.         /* [in] */ BSTR bstrGuidCmdGroup,  
91.         /* [in] */ DWORD nCmdID,  
92.         /* [retval][out] */ HRESULT *dwRetVal)  
93.     {  
94.         return S_FALSE;  
95.     }  
96.   
97.     STDMETHOD(GetOptionKeyPath)(/* [out] */ BSTR *pbstrKey, /* [in] */ DWORD dw){ return S_FALSE;}  
98.     STDMETHOD(GetDropTarget)(/* [in] */ IUnknown *pDropTarget,/* [out] */ IUnknown **ppDropTarget){ return S_FALSE; }  
99.   
100.     STDMETHOD(GetExternal)(/* [out] */ IDispatch **ppDispatch)  
101.     {  
102.         if(!m_pDispatch)  
103.         {  
104.             m_pDispatch = new CExtenalDispatch;  
105.         }  
106.         m_pDispatch->AddRef();  
107.         *ppDispatch = m_pDispatch;  
108.         return S_OK;  
109.     }  
110.     STDMETHOD(TranslateUrl)(/* [in] */ DWORD dwTranslate, /* [in] */ BSTR bstrURLIn, /* [out] */ BSTR *pbstrURLOut){ return S_FALSE; }  
111.     STDMETHOD(FilterDataObject)(/* [in] */ IUnknown *pDO, /* [out] */ IUnknown **ppDORet){ return S_FALSE; }  
112. private:  
113.     long            m_dwRef;  
114.     CExtenalDispatch * m_pDispatch;   
115. };  

class CBrowserHostUIHandlerImpl : public IDispatchImpl<IDocHostUIHandlerDispatch, &IID_IDocHostUIHandlerDispatch, &LIBID_ATLLib>{public:CBrowserHostUIHandlerImpl(){m_dwRef = 0;m_pDispatch = NULL;}~CBrowserHostUIHandlerImpl(){if(m_pDispatch){m_pDispatch->Release();m_pDispatch = NULL;}}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_IUnknown))*ppvObject = (IUnknown*)this;else if(IsEqualIID(iid, IID_IDispatch))*ppvObject = (IDispatch*)this;else if (IsEqualIID(iid, __uuidof(IDocHostUIHandler)))*ppvObject = (IDocHostUIHandler*)this;elsehrRet = E_NOINTERFACE;if (S_OK == hrRet)((IUnknown*)*ppvObject)->AddRef();return hrRet;}STDMETHOD(ShowContextMenu)(/* [in] */ DWORD dwID,/* [in] */ DWORD x,/* [in] */ DWORD y,/* [in] */ IUnknown *pcmdtReserved,/* [in] */ IDispatch *pdispReserved,/* [retval][out] */ HRESULT *dwRetVal){*dwRetVal = S_OK;return S_OK;}STDMETHOD(GetHostInfo)(/* [out][in] */ DWORD *pdwFlags,/* [out][in] */ DWORD *pdwDoubleClick){*pdwFlags = DOCHOSTUIFLAG_DIV_BLOCKDEFAULT | DOCHOSTUIFLAG_CODEPAGELINKEDFONTS | DOCHOSTUIFLAG_THEME | DOCHOSTUIFLAG_SCROLL_NO | DOCHOSTUIFLAG_NO3DBORDER;*pdwDoubleClick = DOCHOSTUIDBLCLK_DEFAULT;return S_OK;}STDMETHOD(ShowUI)(/* [in] */ DWORD dwID,/* [in] */ IUnknown *pActiveObject,/* [in] */ IUnknown *pCommandTarget,/* [in] */ IUnknown *pFrame,/* [in] */ IUnknown *pDoc,/* [retval][out] */ HRESULT *dwRetVal){return S_OK;}STDMETHOD(HideUI)(){ return S_OK; }STDMETHOD(UpdateUI)(){ return S_OK; }STDMETHOD(EnableModeless)(/* [in] */ VARIANT_BOOL fEnable){ return S_OK; }STDMETHOD(OnDocWindowActivate)(/* [in] */ VARIANT_BOOL fActivate){ return S_OK; }STDMETHOD(OnFrameWindowActivate)(/* [in] */ VARIANT_BOOL fActivate){ return S_OK; }STDMETHOD(ResizeBorder)(/* [in] */ long left,/* [in] */ long top,/* [in] */ long right,/* [in] */ long bottom,/* [in] */ IUnknown *pUIWindow,/* [in] */ VARIANT_BOOL fFrameWindow){return S_OK;}STDMETHOD(TranslateAccelerator)(/* [in] */ DWORD_PTR hWnd,/* [in] */ DWORD nMessage,/* [in] */ DWORD_PTR wParam,/* [in] */ DWORD_PTR lParam,/* [in] */ BSTR bstrGuidCmdGroup,/* [in] */ DWORD nCmdID,/* [retval][out] */ HRESULT *dwRetVal){return S_FALSE;}STDMETHOD(GetOptionKeyPath)(/* [out] */ BSTR *pbstrKey,/* [in] */ DWORD dw){ return S_FALSE;}STDMETHOD(GetDropTarget)(/* [in] */ IUnknown *pDropTarget,/* [out] */ IUnknown **ppDropTarget){ return S_FALSE;}STDMETHOD(GetExternal)(/* [out] */ IDispatch **ppDispatch){if(!m_pDispatch){m_pDispatch = new CExtenalDispatch;}m_pDispatch->AddRef();*ppDispatch = m_pDispatch;return S_OK;}STDMETHOD(TranslateUrl)(/* [in] */ DWORD dwTranslate, /* [in] */ BSTR bstrURLIn, /* [out] */ BSTR *pbstrURLOut){ return S_FALSE; }STDMETHOD(FilterDataObject)(/* [in] */ IUnknown *pDO, /* [out] */ IUnknown **ppDORet){ return S_FALSE; }private:longm_dwRef;CExtenalDispatch * m_pDispatch;};

 

最后，在WebBrowser控制创建好后，调用SetExternalUIHandler。如下：

[cpp] view plaincopyprint?

1. CBrowserHostUIHandlerImpl * pHost = new CBrowserHostUIHandlerImpl;  
2. pHost->AddRef();  
3. SetExternalUIHandler(pHost);  

来源 ：http://blog.csdn.net/yyan/article/details/4814866