窗口截圖(二)

窗口截圖，可以獲取遮擋窗口完整的圖像，並保存到bmp文件中去。主要用到的函數中PrintWindow，VC6不支持該函數，請使用VS2008來編譯。其它需求如平臺要求請參考MSDN文檔。

void SaveHwndToBmpFile(HWND hWnd, LPCTSTR lpszPath)
{
    HDC hDC = ::GetWindowDC(hWnd);
    ASSERT(hDC);

    HDC hMemDC = ::CreateCompatibleDC(hDC);
    ASSERT(hMemDC);

    RECT rc;
    ::GetWindowRect(hWnd, &rc);

    HBITMAP hBitmap = ::CreateCompatibleBitmap(hDC, rc.right - rc.left, rc.bottom - rc.top);
    ASSERT(hBitmap);

    HBITMAP hOldBmp = (HBITMAP)::SelectObject(hMemDC, hBitmap);
    ::PrintWindow(hWnd, hMemDC, 0);

    BITMAP bitmap = {0};
    ::GetObject(hBitmap, sizeof(BITMAP), &bitmap);
    BITMAPINFOHEADER bi = {0};
    BITMAPFILEHEADER bf = {0};

    CONST int nBitCount = 24;
    bi.biSize = sizeof(BITMAPINFOHEADER);
    bi.biWidth = bitmap.bmWidth;
    bi.biHeight = bitmap.bmHeight;
    bi.biPlanes = 1;
    bi.biBitCount = nBitCount;
    bi.biCompression = BI_RGB;
    DWORD dwSize = ((bitmap.bmWidth * nBitCount + 31) / 32) * 4 * bitmap.bmHeight;

    HANDLE hDib = GlobalAlloc(GHND, dwSize + sizeof(BITMAPINFOHEADER));
    LPBITMAPINFOHEADER lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
    *lpbi = bi;

    ::GetDIBits(hMemDC, hBitmap, 0, bitmap.bmHeight, (BYTE*)lpbi + sizeof(BITMAPINFOHEADER), (BITMAPINFO*)lpbi, DIB_RGB_COLORS);

    try
    {
        CFile file;
        file.Open(lpszPath, CFile::modeCreate | CFile::modeWrite);
        bf.bfType = 0x4d42;
        dwSize += sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
        bf.bfSize = dwSize;
        bf.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

        file.Write((BYTE*)&bf, sizeof(BITMAPFILEHEADER));
        file.Write((BYTE*)lpbi, dwSize);
        file.Close();
    }
    catch(CFileException* e)
    {
        e->ReportError();
        e->Delete();
    }

    GlobalUnlock(hDib);
    GlobalFree(hDib);

    ::SelectObject(hMemDC, hOldBmp);
    ::DeleteObject(hBitmap);
    ::DeleteObject(hMemDC);
    ::ReleaseDC(hWnd, hDC);
}

// 調用方法
HWND hWnd = ::FindWindow(NULL, _T("XXX"));
if(hWnd)
{
   SaveHwndToBmpFile(hWnd, _T("F://12.bmp"));
}