在MFC对话框中使用Google地图(续)

    在完成了基本功能以后，接下来就可以实现输入经纬度在地图中显示地点的功能了。这里就要用到VC和JavaScript的混合编程了。

如何在VC中调用JavaScript的函数，以下两个分别是CWebPage类的.h和.cpp文件：

// WebPage.h: interface for the CWebPage class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_WEBPAGE_H__AEBD50B8_EE66_40AB_8B92_C4EECB9BCD22__INCLUDED_)
#define AFX_WEBPAGE_H__AEBD50B8_EE66_40AB_8B92_C4EECB9BCD22__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <atlbase.h>
#include <Mshtml.h>

class CWebPage  
{
public:
    CWebPage();
    virtual ~CWebPage();

    bool SetDocument(IDispatch* pDisp);
    LPDISPATCH GetHtmlDocument() const;
    const CString GetLastError() const;
    bool GetJScript(CComPtr<IDispatch>& spDisp);
    bool GetJScripts(CComPtr<IHTMLElementCollection>& spColl);

    CString ScanJScript(CString& strAText, CStringArray& args);

    bool CallJScript(const CString strFunc,CComVariant* pVarResult = NULL);
    bool CallJScript(const CString strFunc,const CString strArg1,CComVariant* pVarResult = NULL);
    bool CallJScript(const CString strFunc,const CString strArg1,const CString strArg2,CComVariant* pVarResult = NULL);
    bool CallJScript(const CString strFunc,const CString strArg1,const CString strArg2,const CString strArg3,CComVariant* pVarResult = NULL);
    bool CallJScript(const CString strFunc,const CStringArray& paramArray,CComVariant* pVarResult = NULL);

protected:


    void ShowError(LPCSTR lpszText);

protected:

    CComPtr<IHTMLDocument2>    m_spDoc;
    CString    m_strError;

};

inline
void CWebPage::ShowError(LPCSTR lpszText)
{
    m_strError = "JSCall Error:
" + CString(lpszText);
}
inline 
const CString CWebPage::GetLastError() const
{
    return m_strError;
}
inline
LPDISPATCH CWebPage::GetHtmlDocument() const
{
    return m_spDoc;
}

CString GetNextToken(CString& strSrc, const CString strDelim,bool bTrim = false, bool bFindOneOf = true);

#endif // !defined(AFX_WEBPAGE_H__AEBD50B8_EE66_40AB_8B92_C4EECB9BCD22__INCLUDED_)

/////////////////////////////////////////////////////////////////
//             By Eugene Khodakovsky                           //
//                  April,2002                                 //
//             Eugene@cpplab.com                               //
//            Last Update: April, 2002                         //
/////////////////////////////////////////////////////////////////

////////           WebPage.cpp

#include "stdafx.h"
//#include "JSCall.h"
#include "WebPage.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

#define CHECK_POINTER(p)
    ATLASSERT(p != NULL);
    if(p == NULL)
    {
        ShowError("NULL pointer");
        return false;
    }

const CString GetSystemErrorMessage(DWORD dwError)
{
    CString strError;
    LPTSTR lpBuffer;

    if(!FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
            NULL,  dwError,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_SYS_DEFAULT),
            (LPTSTR) &lpBuffer, 0, NULL))

    {
        strError = "FormatMessage Netive Error" ;
    }
    else
    {
        strError = lpBuffer;
        LocalFree(lpBuffer);
    }
    return strError;
}

CString GetNextToken(CString& strSrc, const CString strDelim,bool bTrim, bool bFindOneOf)
{
    CString strToken;
    int idx = bFindOneOf? strSrc.FindOneOf(strDelim) : strSrc.Find(strDelim);
    if(idx != -1)
    {
        strToken  = strSrc.Left(idx);
        strSrc = strSrc.Right(strSrc.GetLength() - (idx + 1) );
    }
    else
    {
        strToken = strSrc;
        strSrc.Empty();
    }
    if(bTrim)
    {
        strToken.TrimLeft();
        strToken.TrimRight();
    }
    return strToken;
}

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CWebPage::CWebPage()
{
}

CWebPage::~CWebPage()
{

}

bool CWebPage::SetDocument(IDispatch* pDisp)
{
    CHECK_POINTER(pDisp);

    m_spDoc = NULL;

    CComPtr<IDispatch> spDisp = pDisp;

    HRESULT hr = spDisp->QueryInterface(IID_IHTMLDocument2,(void**)&m_spDoc);
    if(FAILED(hr))
    {
        ShowError("Failed to get HTML document COM object");
        return false;
    }
    return true;
}

bool CWebPage::GetJScript(CComPtr<IDispatch>& spDisp)
{
    CHECK_POINTER(m_spDoc);
    HRESULT hr = m_spDoc->get_Script(&spDisp);
    ATLASSERT(SUCCEEDED(hr));
    return SUCCEEDED(hr);
}

bool CWebPage::GetJScripts(CComPtr<IHTMLElementCollection>& spColl)
{
    CHECK_POINTER(m_spDoc);
    HRESULT hr = m_spDoc->get_scripts(&spColl);
    ATLASSERT(SUCCEEDED(hr));
    return SUCCEEDED(hr);
}

bool CWebPage::CallJScript(const CString strFunc,CComVariant* pVarResult)
{
    CStringArray paramArray;
    return CallJScript(strFunc,paramArray,pVarResult);
}

bool CWebPage::CallJScript(const CString strFunc,const CString strArg1,CComVariant* pVarResult)
{
    CStringArray paramArray;
    paramArray.Add(strArg1);
    return CallJScript(strFunc,paramArray,pVarResult);
}

bool CWebPage::CallJScript(const CString strFunc,const CString strArg1,const CString strArg2,CComVariant* pVarResult)
{
    CStringArray paramArray;
    paramArray.Add(strArg1);
    paramArray.Add(strArg2);
    return CallJScript(strFunc,paramArray,pVarResult);
}

bool CWebPage::CallJScript(const CString strFunc,const CString strArg1,const CString strArg2,const CString strArg3,CComVariant* pVarResult)
{
    CStringArray paramArray;
    paramArray.Add(strArg1);
    paramArray.Add(strArg2);
    paramArray.Add(strArg3);
    return CallJScript(strFunc,paramArray,pVarResult);
}

bool CWebPage::CallJScript(const CString strFunc, const CStringArray& paramArray,CComVariant* pVarResult)
{
    CComPtr<IDispatch> spScript;
    if(!GetJScript(spScript))
    {
        ShowError("Cannot GetScript");
        return false;
    }
    CComBSTR bstrMember(strFunc);
    DISPID dispid = NULL;
    HRESULT hr = spScript->GetIDsOfNames(IID_NULL,&bstrMember,1,
                                            LOCALE_SYSTEM_DEFAULT,&dispid);
    if(FAILED(hr))
    {
        ShowError(GetSystemErrorMessage(hr));
        return false;
    }

    const int arraySize = paramArray.GetSize();

    DISPPARAMS dispparams;
    memset(&dispparams, 0, sizeof dispparams);
    dispparams.cArgs = arraySize;
    dispparams.rgvarg = new VARIANT[dispparams.cArgs];
    
    for( int i = 0; i < arraySize; i++)
    {
        CComBSTR bstr = paramArray.GetAt(arraySize - 1 - i); // back reading
        bstr.CopyTo(&dispparams.rgvarg[i].bstrVal);
        dispparams.rgvarg[i].vt = VT_BSTR;
    }
    dispparams.cNamedArgs = 0;

    EXCEPINFO excepInfo;
    memset(&excepInfo, 0, sizeof excepInfo);
       CComVariant vaResult;
    UINT nArgErr = (UINT)-1;  // initialize to invalid arg
         
    hr = spScript->Invoke(dispid,IID_NULL,0,
                            DISPATCH_METHOD,&dispparams,&vaResult,&excepInfo,&nArgErr);

    delete [] dispparams.rgvarg;
    if(FAILED(hr))
    {
        ShowError(GetSystemErrorMessage(hr));
        return false;
    }
    
    if(pVarResult)
    {
        *pVarResult = vaResult;
    }
    return true;
}

// returned java script function name, input string is truncating
CString CWebPage::ScanJScript(CString& strAText, CStringArray& args)
{
    args.RemoveAll();
    CString strDelim(" 

	"),strSrc(strAText);
    bool bFound = false;
    while(!strSrc.IsEmpty())
    {
        CString strStart = GetNextToken(strSrc,strDelim);
        if(strStart == "function")
        {
            bFound = true;
            break;
        }
        if(strStart == "/*")
        {
            // Skip comments
            while(!strSrc.IsEmpty())
            {
                CString strStop = GetNextToken(strSrc,strDelim);
                if(strStop == "*/")
                {
                    break;
                }
            }
        }
    }

    if(!bFound)
        return "";
    
    CString strFunc = GetNextToken(strSrc,"(",true);
    CString strArgs = GetNextToken(strSrc,")",true);

    // Parse arguments
    CString strArg;
    while(!(strArg = GetNextToken(strArgs,",")).IsEmpty())
        args.Add(strArg);

    strAText= strSrc;
    return strFunc;
}

     在对话框中添加测试调用JS函数按钮，在XXXDlg.cpp中该按钮单击消息函数中加入代码如下：

    CWebPage web;
    web.SetDocument(m_webBrowser.GetDocument());
    web.CallJScript("jsfunctiontest");//调用JS中的jsfunctiontest函数

然后编译运行，点击按钮就会有一个名为来自网页消息弹出框，测试成功，实现VC和JavaScript的混合编程。

在对话框中添加两个编辑框和一个按钮，在编辑框中输入经度和纬度，点击按钮谷歌地图跳转到相应的地点。

按钮的点击消息响应函数中代码如下：

    UpdateData(TRUE);//将控件上的值传回变量

    CWebPage web;
    web.SetDocument(m_webBrowser.GetDocument());
    //调用JS中的函数TansTo()，并传递2个参数(纬度，经度)
    web.CallJScript("TansTo", m_latitude, m_longitude);

好了，以上完成了输入经纬度在地图中显示地点的功能。

接下来就可以仔细的分析代码了。