winapi 截屏函数（转）

void screen(wchar_t* fileName)
{
    HWND window = GetDesktopWindow();
    HDC _dc = GetWindowDC(window);//屏幕DC
    HDC dc = CreateCompatibleDC(0);//内存DC
    
    RECT re;
    GetWindowRect(window, &re);
    int w = re.right,
        h = re.bottom;
    void* buf = new char[w*h*4];
    
    HBITMAP bm = CreateCompatibleBitmap(_dc, w, h);//建立和屏幕兼容的bitmap
    SelectObject(dc, bm);//将memBitmap选入内存DC    
    StretchBlt(dc, 0, 0, w, h, _dc, 0, 0, w, h, SRCCOPY);//复制屏幕图像到内存DC
    
    void* f =CreateFile(fileName, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, 0, 0);
    
    GetObject(bm, 84, buf);
    
    tagBITMAPINFO bi;
    bi.bmiHeader.biSize = sizeof(bi.bmiHeader);
    bi.bmiHeader.biWidth = w;
    bi.bmiHeader.biHeight = h;
    bi.bmiHeader.biPlanes = 1;
    bi.bmiHeader.biBitCount = 32;
    bi.bmiHeader.biCompression = 0;
    bi.bmiHeader.biSizeImage = 0;
    
    CreateDIBSection(dc, &bi, DIB_RGB_COLORS, &buf, 0, 0);
    GetDIBits(dc, bm, 0, h, buf, &bi, DIB_RGB_COLORS);
        
    BITMAPFILEHEADER bif;
    bif.bfType = MAKEWORD('B','M');
    bif.bfSize = w*h*4+54;
    bif.bfOffBits = 54;

    BITMAPINFOHEADER bii;
    bii.biSize = 40;
    bii.biWidth = w;
    bii.biHeight = h;
    bii.biPlanes = 1;
    bii.biBitCount = 32;
    bii.biCompression = 0;
    bii.biSizeImage = w*h*4;
    
    DWORD r;
    WriteFile(f, &bif, sizeof(bif), &r, NULL);
    WriteFile(f, &bii, sizeof(bii), &r, NULL);
    WriteFile(f, buf, w*h*4, &r, NULL);

    CloseHandle(f);
    DeleteDC(_dc);
    DeleteDC(dc);
}