Trident内核中取验证码图片的几种方法

程序中用了IE的内核，想取出网站中的验证码图片，单独显示出来，调研了以下几路方法

1、枚举所有缓存文件，进行处理，找到想要的，核心代码

if (0)//这段代码可以枚举所有缓存资源，然后对应做处理
{
    LPINTERNET_CACHE_ENTRY_INFO lpCacheEntry = NULL;
    HANDLE hCacheDir = NULL;
    DWORD dwTrySize, dwEntrySize = 4096;
    DWORD dwError = ERROR_INSUFFICIENT_BUFFER;
    BOOL bSuccess, bDone = FALSE; //是否已经处理完，初始设为false
    while(!bDone){
        switch(dwError){
        case ERROR_INSUFFICIENT_BUFFER:     
            if(lpCacheEntry) 
            {
                delete [] lpCacheEntry;
            }
            lpCacheEntry = (LPINTERNET_CACHE_ENTRY_INFO) new char[dwEntrySize];
            lpCacheEntry->dwStructSize = dwEntrySize;
            dwTrySize = dwEntrySize;
            if(!hCacheDir)
            {//为空，说明第一次执行，需要找第一个
                hCacheDir = FindFirstUrlCacheEntry(NULL,lpCacheEntry,&dwTrySize);
                bSuccess = (hCacheDir != NULL);
            }
            else 
            {
                bSuccess = FindNextUrlCacheEntry(hCacheDir,lpCacheEntry,&dwTrySize);
            }
            if(!bSuccess){
                dwError = GetLastError();
                dwEntrySize = dwTrySize; //使用得到的新长度 
            }
            else 
            {
                dwError = ERROR_SUCCESS;
            }
            break; 
            //we are done
        case ERROR_NO_MORE_ITEMS:
            bDone = TRUE;
            break;
            //we have got an entry
        case ERROR_SUCCESS:
            if(bSuccess && (NORMAL_CACHE_ENTRY & lpCacheEntry->CacheEntryType))
            { //
                CString sUrl1 = lpCacheEntry->lpszSourceUrlName;
                if (sUrl1.Compare(s) == 0)
                {
                    //处理
                }
                //     CTime lastModified(lpCacheEntry->LastModifiedTime);
                //     CTime lastAccessed(lpCacheEntry->LastAccessTime);
                //a changed cookie - delete it!
                //     if(lastModified >= m_time || lastAccessed >= m_time){
                //const   CString   name   =   lpCacheEntry->lpszSourceUrlName;  
                //const   CString   result   =   lastModified.Format("%I:%M:%S%p   %d   %b   %Y");  
                //MessageBox   (NULL,   name   +   "   last   modified   "   +   result,   "Deleting cookie",   MB_OK);  
                //DeleteUrlCacheEntry(lpCacheEntry->lpszSourceUrlName);
            }
            //get ready for next entry
            dwTrySize = dwEntrySize;
            if(!FindNextUrlCacheEntry(hCacheDir,lpCacheEntry,&dwTrySize))
            {
                dwError = GetLastError();
                dwEntrySize = dwTrySize;   //使用得到的新长度
            }
            else 
            {
                dwError = ERROR_SUCCESS;
            }
            break;
            //unknown error
        default:
            CString strError; strError.Format(_T("There is an error (%d) when trying deleting temporary internet files.\r\n"),   dwError);  
            TRACE(strError);
            bDone = TRUE;
            break;   
            if(bDone) 
                break;
            Sleep(10);  if(lpCacheEntry){ delete [] lpCacheEntry; lpCacheEntry = NULL;}
            if(hCacheDir){ FindCloseUrlCache(hCacheDir); hCacheDir = NULL;}
            break;
        }
    }
}

2、直接取某个URL对应的缓存资源

if (1)//这段代码可以直接从缓存找到对应URL的图片资源的路径
{
    CString s = dispImg.Get(L"src");
    if (1)
    {
        LPINTERNET_CACHE_ENTRY_INFO lpCacheEntry = NULL;
        DWORD dwEntrySize = 4096;
        lpCacheEntry = (LPINTERNET_CACHE_ENTRY_INFO) new char[dwEntrySize];
        lpCacheEntry->dwStructSize = dwEntrySize;
        BOOL b = GetUrlCacheEntryInfo(s, lpCacheEntry, &dwEntrySize);
        CString sPath = lpCacheEntry->lpszLocalFileName;
    }
}

3、在网页新建一canvas，将图片绘上，然后toDataURL，这样可以得到png格式的，经过base64编码后的字符串，该方法只能在ie9以上使用

if (0)//这段代码只能在IE9以上运行，可以将图片绘到canvas上，再取出png格式经base64编码后的数据
    //然后解码，存到文件中，就得到一个png图片
    //HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION
    //设置对应程序的dword值为10001为强制ie10，9999为强制ie9，8888为强制ie8
{
    CDispatch dispCanvas = disp.InvokePtr(L"createElement", L"canvas");
    dispCanvas.Put(L"width", dispImg.Get(L"naturalWidth"));
    dispCanvas.Put(L"height", dispImg.Get(L"naturalHeight"));
    CDispatch dispCtx = dispCanvas.InvokePtr(L"getContext", L"2d");
    dispCtx.Invoke(L"drawImage", dispImg.p, 0, 0);
    CString sData = dispCanvas.Invoke(L"toDataURL", L"image/png");
    sData = sData.Right(sData.GetLength() - 22);

    int nBuffer = sData.GetLength() + 1;
    byte* buffer = new byte[nBuffer];
    memset(buffer, 0, nBuffer);
    Base64Decode(sData, sData.GetLength(), buffer, &nBuffer);

    CFile f("1.png", CFile::modeCreate|CFile::modeWrite);
    f.Write(buffer, nBuffer);
    delete[] buffer;
}