Trident內核中取驗證碼圖片的幾種方法

程序中用了IE的內核，想取出網站中的驗證碼圖片，單獨顯示出來，調研瞭如下幾路方法

一、枚舉全部緩存文件，進行處理，找到想要的，核心代碼

if (0)//這段代碼能夠枚舉全部緩存資源，而後對應作處理
{
    LPINTERNET_CACHE_ENTRY_INFO lpCacheEntry = NULL;
    HANDLE hCacheDir = NULL;
    DWORD dwTrySize, dwEntrySize = 4096;
    DWORD dwError = ERROR_INSUFFICIENT_BUFFER;
    BOOL bSuccess, bDone = FALSE; //是否已經處理完，初始設爲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)
            {//爲空，說明第一次執行，須要找第一個
                hCacheDir = FindFirstUrlCacheEntry(NULL,lpCacheEntry,&dwTrySize);
                bSuccess = (hCacheDir != NULL);
            }
            else 
            {
                bSuccess = FindNextUrlCacheEntry(hCacheDir,lpCacheEntry,&dwTrySize);
            }
            if(!bSuccess){
                dwError = GetLastError();
                dwEntrySize = dwTrySize; //使用獲得的新長度 
            }
            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)
                {
                    //處理
                }
                //     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;   //使用獲得的新長度
            }
            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;
        }
    }
}

二、直接取某個URL對應的緩存資源

if (1)//這段代碼能夠直接從緩存找到對應URL的圖片資源的路徑
{
    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;
    }
}

三、在網頁新建一canvas，將圖片繪上，而後toDataURL，這樣能夠獲得png格式的，通過base64編碼後的字符串，該方法只能在ie9以上使用

if (0)//這段代碼只能在IE9以上運行，能夠將圖片繪到canvas上，再取出png格式經base64編碼後的數據
    //而後解碼，存到文件中，就獲得一個png圖片
    //HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION
    //設置對應程序的dword值爲10001爲強制ie10，9999爲強制ie9，8888爲強制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;
}