PAINTSTRUCT ps;

    HDC hdc = BeginPaint(hwnd,&ps);

    HDC hMemDC = CreateCompatibleDC(hdc);

    HBITMAP hBitmap = LoadBitmap(g_hIntance,MAKEINTRESOURCE(IDB_BITMAP1));

    HBITMAP hOldBitmap = (HBITMAP)SelectObject(hMemDC,hBitmap);

    //把HBITMAP转换成BITMAP，从而获取位图的宽高。

    BITMAP bmp;

    GetObject(hBitmap, sizeof(BITMAP), &bmp);

    BitBlt(hdc,,,bmp.bmWidth,bmp.bmHeight,hMemDC,,,SRCCOPY);

    SelectObject(hMemDC,hOldBitmap);

    DeleteObject(hBitmap);

    DeleteDC(hMemDC);

    EndPaint(hwnd,&ps);    

    PAINTSTRUCT ps;

    HDC hdcClient = BeginPaint(hwnd, &ps);

    HDC hdcScreen = CreateDC(TEXT("DISPLAY"), NULL, NULL, NULL);

    RECT rtClient;

    int scrWidth = GetSystemMetrics(SM_CXSCREEN);

    int scrHeight = GetSystemMetrics(SM_CYSCREEN);

    GetClientRect(hwnd,&rtClient);

    StretchBlt(hdcClient,,,rtClient.right,rtClient.bottom,

        hdcScreen,,,scrWidth,scrHeight,SRCCOPY);

    DeleteDC(hdcScreen);

    EndPaint(hwnd, &ps);