从在Web浏览器控件中运行的JavaScript脚本调用C ++函数 [英] Calling C++ function from JavaScript script running in a web browser control

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问题描述

我在我的c ++应用程序中嵌入了一个Web浏览器控件。我想让JavaScript在Web浏览器控件中运行，以便能够调用一个c ++函数/方法。



我发现有三种方法可以做到这一点：


  1. 实现充当中间人的ActiveX组件。 （实现细节： http://blogs.msdn.com/b/nicd/archive/2007/04/18/calling-into-your-bho-from-a-client-script.aspx ）

  2. 使用window.external。 （也在上面的链接中讨论，但没有提供实现）

  3. 向窗口对象添加自定义对象

我想使用第三个选项，但我没有找到任何工作示例如何做到这一点。有人可以告诉我如何做，或链接到一个工作示例在网络的某个地方。



最接近的例子，我发现是第一个回复Igor Tandetnik在 webbrowser_ctl新闻组中的主题。但我恐怕需要更多的帮助。



我嵌入了一个IWebBrowser2控件，我没有使用MFC，ATL或WTL。



编辑：



通过Igor在我之前链接的线程中提供的伪代码，以及代码项目文章从C ++创建JavaScript数组和其他对象中找到的代码生成了一些代码。

  void WebForm :: AddCustomObject（IDispatch * custObj，std :: string name）
 {
 IHTMLDocument2 * doc = GetDoc（）; 
 IHTMLWindow2 * win = NULL; 
 doc-> get_parentWindow（& win）; 
 
 if（win == NULL）{
 return; 
} 
 
 IDispatchEx * winEx; 
 win-> QueryInterface（& winEx）; 
 
 if（winEx == NULL）{
 return; 
} 
 
 int lenW = MultiByteToWideChar（CP_ACP，MB_PRECOMPOSED，name.c_str（），-1，NULL，0）; 
 BSTR objName = SysAllocStringLen（0，lenW）; 
 MultiByteToWideChar（CP_ACP，MB_PRECOMPOSED，name.c_str（），-1，objName，lenW）; 
 
 DISPID dispid; 
 HRESULT hr = winEx-> GetDispID（objName，fdexNameEnsure，& dispid）; 
 
 SysFreeString（objName）; 
 
 if（FAILED（hr））{
 return; 
} 
 
 DISPID namedArgs [] = {DISPID_PROPERTYPUT}; 
 DISPPARAMS params; 
 params.rgvarg = new VARIANT [1]; 
 params.rgvarg [0] .pdispVal = custObj; 
 params.rgvarg [0] .vt = VT_DISPATCH; 
 params.rgdispidNamedArgs = namedArgs; 
 params.cArgs = 1; 
 params.cNamedArgs = 1; 
 
 hr = winEx-> InvokeEx（dispid，LOCALE_USER_DEFAULT，DISPATCH_PROPERTYPUT，& params，NULL，NULL，NULL）; 
 
 if（FAILED（hr））{
 return; 
} 
}

上面的代码一直运行，



当我收到DISPID_NAVIGATECOMPLETE2 DWebBrowserEvents2事件时，调用AddCustomObject传递 * custObj ：

  class JSObject：public IDispatch {
 private：
 long ref; 
 
 public：
 // IUnknown 
 virtual HRESULT STDMETHODCALLTYPE QueryInterface（REFIID riid，void ** ppv）; 
 virtual ULONG STDMETHODCALLTYPE AddRef（）; 
 virtual ULONG STDMETHODCALLTYPE Release（）; 
 
 // IDispatch 
 virtual HRESULT STDMETHODCALLTYPE GetTypeInfoCount（UINT * pctinfo）; 
 virtual HRESULT STDMETHODCALLTYPE GetTypeInfo（UINT iTInfo，LCID lcid，
 ITypeInfo ** ppTInfo）; 
 virtual HRESULT STDMETHODCALLTYPE GetIDsOfNames（REFIID riid，
 LPOLESTR * rgszNames，UINT cNames，LCID lcid，DISPID * rgDispId）; 
 virtual HRESULT STDMETHODCALLTYPE Invoke（DISPID dispIdMember，REFIID riid，
 LCID lcid，WORD wFlags，DISPPARAMS * Params，VARIANT * pVarResult，
 EXCEPINFO * pExcepInfo，UINT * puArgErr）; 
};

值得注意的实现可能是

  HRESULT STDMETHODCALLTYPE JSObject :: QueryInterface（REFIID riid，void ** ppv）
 {
 * ppv = NULL; 
 
 if（riid == IID_IUnknown || riid == IID_IDispatch）{
 * ppv = static_cast< IDispatch *> 
} 
 
 if（* ppv！= NULL）{
 AddRef（）; 
 return S_OK; 
} 
 
 return E_NOINTERFACE; 
}

及

  HRESULT STDMETHODCALLTYPE JSObject :: Invoke（DISPID dispIdMember，REFIID riid，
 LCID lcid，WORD wFlags，DISPPARAMS * Params，VARIANT * pVarResult，
 EXCEPINFO * pExcepInfo， puArgErr）
 {
 MessageBox（NULL，Invoke，JSObject，MB_OK）; 
 return DISP_E_MEMBERNOTFOUND;不幸的是我从来没有得到Invoke消息框，当我尝试使用
  JSObject.randomFunctionName（）; //这应该给我c ++Invoke消息
 // box，但它不会
  
 
 $ b b 
 编辑2： 
 
 
 
我实现了 GetIDsOfNames  p> 
 
 
  HRESULT STDMETHODCALLTYPE JSObject :: GetIDsOfNames（REFIID riid，
 LPOLESTR * rgszNames，UINT cNames，LCID lcid，DISPID * rgDispId） 
 {
 HRESULT hr = S_OK; 
 
 for（UINT i = 0; i  std :: map< std :: wstring，DISPID> :: iterator iter = idMap.find（rgszNames [一世]）; 
 if（iter！= idMap.end（））{
 rgDispId [i] = iter-> second; 
} else {
 rgDispId [i] = DISPID_UNKNOWN; 
 hr = DISP_E_UNKNOWNNAME; 
} 
} 
 
 return hr; 
} 
  
这是我的构造函数
  JSObject :: JSObject（）：ref（0）
 {
 idMap.insert（std :: make_pair（Lexecute，DISPID_USER_EXECUTE）） ; 
 idMap.insert（std :: make_pair（Lwritefile，DISPID_USER_WRITEFILE））; 
 idMap.insert（std :: make_pair（Lreadfile，DISPID_USER_READFILE））; 
} 
  
将DISPID_USER_ *常数定义为私有类成员
  class JSObject：public IDispatch {
 private：
 static const DISPID DISPID_USER_EXECUTE = DISPID_VALUE + 
 static const DISPID DISPID_USER_WRITEFILE = DISPID_VALUE + 2; 
 static const DISPID DISPID_USER_READFILE = DISPID_VALUE + 3; 
 
 // ... 
}; 
  
 编辑3,4和5： b 
 
已移至另一个问题 
 
 
 
 编辑6： 
 
 
 
 Made 一个单独的问题出返回字符串编辑。这样，我可以接受 Georg's 的回复，因为回答了原始问题。
 
 
 
 编辑7： 
 
 
 
我收到了一些完全工作，自包含示例实现的请求。这里是： https://github.com/Tobbe/CppIEEmbed 。如果你可以：）
解决方案
你需要实现 GetIDsOfNames c $ c>做一些明智的事情，因为该函数将由客户端代码在 Invoke（）之前调用。
 
如果您的接口类型库，请参见此处的示例。如果您要使用延迟绑定，可以使用  DISPID  s 大于 DISPID_VALUE 且少于 0x80010000 （所有值< = 0 和 0x80010000 到 0x8001FFFF  ）：
  HRESULT GetIDsOfNames（REFIID riid，LPOLESTR * rgszNames，UINT cNames，
 LCID lcid，DISPID * rgDispId） 
 {
 HR hr = S_OK; 
 for（UINT i = 0; i  if（validName（rgszNames））{
 rgDispId [i] = dispIdForName（rgszNames）; 
} else {
 rgDispId [i] = DISPID_UNKNOWN; 
 hr = DISP_E_UNKNOWNNAME; 
} 
} 
 return hr; 
} 
 
 HRESULT调用（DISPID dispIdMember，REFIID riid，LCID lcid，WORD wFlags，
 DISPPARAMS * Params，VARIANT * pVarResult，EXCEPINFO * pExcepInfo，
 UINT * puArgErr）
 {
 if（wFlags& DISPATCH_METHOD）{
 //根据DISPID ...处理
} 
 
 // ... 
  
请注意， DISPID 突然改变，例如应使用静态映射或常量值。
 
I have embedded a web browser control in my c++ application. I want javascript running in the web browser control to be able to call a c++ function/method.



I have found mentions of three ways to do this:
    

  1. Implement an ActiveX component that acts as a middle man. (Implementation details here: http://blogs.msdn.com/b/nicd/archive/2007/04/18/calling-into-your-bho-from-a-client-script.aspx)
    2. 

  2. Use window.external. (Also discussed in the link above, but no implementation provided)
    3. 

  3. Add a custom object to the window object
    4. 

I want to go with the third option, but I haven't found any working examples on how to do that. Can someone please show me how to do it, or link to a working example on the net somewhere.



The closest to an example that I have found is the first reply by Igor Tandetnik in a thread in the webbrowser_ctl news group. But I'm afraid I need more help than that.



I'm embedding an IWebBrowser2 control and I am not using MFC, ATL or WTL.



EDIT:



Going by the pseudo-code given by Igor in the thread I linked earlier, and code found in the codeproject article "Creating JavaScript arrays and other objects from C++" I've produced some code.
void WebForm::AddCustomObject(IDispatch *custObj, std::string name)
{
    IHTMLDocument2 *doc = GetDoc();
    IHTMLWindow2 *win = NULL;
    doc->get_parentWindow(&win);

    if (win == NULL) {
        return;
    }

    IDispatchEx *winEx;
    win->QueryInterface(&winEx);

    if (winEx == NULL) {
        return;
    }

    int lenW = MultiByteToWideChar(CP_ACP, MB_PRECOMPOSED, name.c_str(), -1, NULL, 0);
    BSTR objName = SysAllocStringLen(0, lenW);
    MultiByteToWideChar(CP_ACP, MB_PRECOMPOSED, name.c_str(), -1, objName, lenW);

    DISPID dispid; 
    HRESULT hr = winEx->GetDispID(objName, fdexNameEnsure, &dispid);

    SysFreeString(objName);

    if (FAILED(hr)) {
        return;
    }

    DISPID namedArgs[] = {DISPID_PROPERTYPUT};
    DISPPARAMS params;
    params.rgvarg = new VARIANT[1];
    params.rgvarg[0].pdispVal = custObj;
    params.rgvarg[0].vt = VT_DISPATCH;
    params.rgdispidNamedArgs = namedArgs;
    params.cArgs = 1;
    params.cNamedArgs = 1;

    hr = winEx->InvokeEx(dispid, LOCALE_USER_DEFAULT, DISPATCH_PROPERTYPUT, &params, NULL, NULL, NULL); 

    if (FAILED(hr)) {
        return;
    }
}

The code above runs all the way through, so everything looks alright that far.



I call AddCustomObject when I receive the DISPID_NAVIGATECOMPLETE2 DWebBrowserEvents2 event passing this as *custObj:
class JSObject : public IDispatch {
private:
    long ref;

public:
    // IUnknown
    virtual HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, void **ppv);
    virtual ULONG STDMETHODCALLTYPE AddRef();
    virtual ULONG STDMETHODCALLTYPE Release();

    // IDispatch
    virtual HRESULT STDMETHODCALLTYPE GetTypeInfoCount(UINT *pctinfo);
    virtual HRESULT STDMETHODCALLTYPE GetTypeInfo(UINT iTInfo, LCID lcid,
        ITypeInfo **ppTInfo);
    virtual HRESULT STDMETHODCALLTYPE GetIDsOfNames(REFIID riid,
        LPOLESTR *rgszNames, UINT cNames, LCID lcid, DISPID *rgDispId);
    virtual HRESULT STDMETHODCALLTYPE Invoke(DISPID dispIdMember, REFIID riid,
        LCID lcid, WORD wFlags, DISPPARAMS *Params, VARIANT *pVarResult,
        EXCEPINFO *pExcepInfo, UINT *puArgErr);
};

Noteworthy implementations might be
HRESULT STDMETHODCALLTYPE JSObject::QueryInterface(REFIID riid, void **ppv)
{
    *ppv = NULL;

    if (riid == IID_IUnknown || riid == IID_IDispatch) {
        *ppv = static_cast<IDispatch*>(this);
    }

    if (*ppv != NULL) {
        AddRef();
        return S_OK;
    }

    return E_NOINTERFACE;
}

and 
HRESULT STDMETHODCALLTYPE JSObject::Invoke(DISPID dispIdMember, REFIID riid,
    LCID lcid, WORD wFlags, DISPPARAMS *Params, VARIANT *pVarResult,
    EXCEPINFO *pExcepInfo, UINT *puArgErr)
{
    MessageBox(NULL, "Invoke", "JSObject", MB_OK);
    return DISP_E_MEMBERNOTFOUND;
}

Unfortunately I never get the "Invoke" message box when I try to use the "JSObject" object from the javascript code.
JSObject.randomFunctionName();  // This should give me the c++ "Invoke" message
                                // box, but it doesn't

EDIT 2:



I implemented GetIDsOfNames like so:
HRESULT STDMETHODCALLTYPE JSObject::GetIDsOfNames(REFIID riid,
    LPOLESTR *rgszNames, UINT cNames, LCID lcid, DISPID *rgDispId)
{
    HRESULT hr = S_OK;

    for (UINT i = 0; i < cNames; i++) {
        std::map<std::wstring, DISPID>::iterator iter = idMap.find(rgszNames[i]);
        if (iter != idMap.end()) {
            rgDispId[i] = iter->second;
        } else {
            rgDispId[i] = DISPID_UNKNOWN;
            hr = DISP_E_UNKNOWNNAME;
        }
    }

    return hr;
}

and this is my constructor
JSObject::JSObject() : ref(0)
{
    idMap.insert(std::make_pair(L"execute", DISPID_USER_EXECUTE));
    idMap.insert(std::make_pair(L"writefile", DISPID_USER_WRITEFILE));
    idMap.insert(std::make_pair(L"readfile", DISPID_USER_READFILE));
}

with the DISPID_USER_* constants defined as private class members
class JSObject : public IDispatch {
private:
    static const DISPID DISPID_USER_EXECUTE = DISPID_VALUE + 1;
    static const DISPID DISPID_USER_WRITEFILE = DISPID_VALUE + 2;
    static const DISPID DISPID_USER_READFILE = DISPID_VALUE + 3;

    // ...
};

EDIT 3, 4 and 5:



Moved to a separate question



EDIT 6:



Made a separate question out of the "returning a string" edits. That way I can accept Georg's reply as that answers the original question.



EDIT 7:



I have gotten a few requests for a fully working, self contained, example implementation. Here it is: https://github.com/Tobbe/CppIEEmbed. Please fork and improve if you can :)
 解决方案 
You need to implement GetIDsOfNames() to do something sensible as that function will be called by client code before Invoke().

If you have your interfaces in a type library see here for an example. If you want to use late-binding instead, you can use DISPIDs greater DISPID_VALUE and less than 0x80010000 (all values <= 0 and in the range 0x80010000 through 0x8001FFFF are reserved):
HRESULT GetIDsOfNames(REFIID riid, LPOLESTR *rgszNames, UINT cNames, 
                      LCID lcid, DISPID *rgDispId)
{
    HR hr = S_OK;
    for (UINT i=0; i<cNames; ++i) {
        if (validName(rgszNames)) {
            rgDispId[i] = dispIdForName(rgszNames);
        } else {
            rgDispId[i] = DISPID_UNKNOWN;
            hr = DISP_E_UNKNOWNNAME;
        }
    }
    return hr;
}

HRESULT Invoke(DISPID dispIdMember, REFIID riid, LCID lcid, WORD wFlags, 
               DISPPARAMS *Params, VARIANT *pVarResult, EXCEPINFO *pExcepInfo, 
               UINT *puArgErr)
{
    if (wFlags & DISPATCH_METHOD) {
       // handle according to DISPID ...
    }

    // ...

Note that the DISPIDs are not supposed to change suddenly, so e.g. a static map or constant values should be used.


                        
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