Capture screen [c/c++]

CaptureScreen.c

// source: web.archive.org/web/20140326200825/http://it-talk.org/topic2646.html

void CaptureScreen(HWND window)
{
    RECT windowRect;
    GetWindowRect(window, &windowRect);

    int bitmap_dx = windowRect.right-windowRect.left;
    int bitmap_dy = windowRect.bottom-windowRect.top;

    BITMAPINFOHEADER bmpInfoHeader;
    BITMAPFILEHEADER bmpFileHeader;
    BITMAP* pBitmap;

    bmpFileHeader.bfType = 0x4d42;
    bmpFileHeader.bfSize = 0;
    bmpFileHeader.bfReserved1 = 0;
    bmpFileHeader.bfReserved2 = 0;
    bmpFileHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

    bmpInfoHeader.biSize = sizeof(bmpInfoHeader);
    bmpInfoHeader.biWidth = bitmap_dx;
    bmpInfoHeader.biHeight = bitmap_dy;
    bmpInfoHeader.biPlanes = 1;
    bmpInfoHeader.biBitCount = 24;
    bmpInfoHeader.biCompression = BI_RGB;
    bmpInfoHeader.biSizeImage = bitmap_dx*bitmap_dy*(24/8);
    bmpInfoHeader.biXPelsPerMeter = 0;
    bmpInfoHeader.biYPelsPerMeter = 0;
    bmpInfoHeader.biClrUsed = 0;
    bmpInfoHeader.biClrImportant = 0;

    BITMAPINFO info;
    info.bmiHeader = bmpInfoHeader;

    BYTE* memory;
    HDC winDC = GetWindowDC(window);
    HDC bmpDC = CreateCompatibleDC(winDC);
    
    HBITMAP bitmap = CreateDIBSection(winDC, &info, DIB_RGB_COLORS, (void**)&memory, NULL, 0);
    SelectObject(bmpDC, bitmap);//Выбираем в контекст битмэп
    BitBlt(bmpDC, 0, 0, bitmap_dx, bitmap_dy, winDC, 0, 0, SRCCOPY);
    ReleaseDC(window, winDC);

    OPENFILENAME ofn;//Указатель на структуру с данными инициализации диалогового окна
    char strFilter[] = "Файлы данных *.bmp\0";
    char strFileName[MAX_PATH] = "";
    memset(&ofn, 0, sizeof(OPENFILENAME));//Обнуление ofn
    ofn.lStructSize = sizeof(OPENFILENAME);
    ofn.hwndOwner = window;
    ofn.lpstrFilter = strFilter;
    ofn.lpstrFile = strFileName;//Буфер для имени файла
    ofn.nMaxFile = MAX_PATH;//Размер файла
    ofn.lpstrInitialDir = NULL;
    ofn.Flags = OFN_SHOWHELP | OFN_OVERWRITEPROMPT;
    strcpy(strFileName, ofn.lpstrFile);
    GetSaveFileName(&ofn); //MessageBox(hwnd,"Невозможно сохранить файл","О программе...",MB_ICONINFORMATION);
    HANDLE hFile = CreateFile(
        ofn.lpstrFile, 
        GENERIC_WRITE, 
        0,
        NULL,
        OPEN_ALWAYS,
        FILE_ATTRIBUTE_NORMAL,
        NULL);
    if (hFile == INVALID_HANDLE_VALUE) 
        return;
    DWORD dwWritten = 0;
    WriteFile(hFile, &bmpFileHeader, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
    WriteFile(hFile, &bmpInfoHeader, sizeof(BITMAPINFOHEADER), &dwWritten, NULL);
    WriteFile(hFile, memory, bmpInfoHeader.biSizeImage, &dwWritten, NULL);
    CloseHandle(hFile);
}