Gdi+ Take Screenshot multiple monitors

I've a routine to take a screenshot on windows platforms with gdi plus and c++, it works perfectly with only one monitor but when I run it in a machine o VM with 2 monitors it only takes the picture one the pictures.

This it's what I'm doing:

#include <stdlib.h>
#include <windows.h>
#include <iostream>
#include <GdiPlus.h>
#include <wingdi.h>
#include <fstream>
#include <unistd.h>

#pragma comment(lib, "gdiplus.lib")
#pragma comment(lib, "ws2_32.lib")

using namespace std;

// Se encarga de configurar, por asi decirlo, el formato
// de la imagen, este metodo es llamado en gdiscreen al
// momento de guardar la imagen.

int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
  using namespace Gdiplus;
  UINT  num = 0;          // number of image encoders
  UINT  size = 0;         // size of the image encoder array in bytes

  ImageCodecInfo* pImageCodecInfo = NULL;

  GetImageEncodersSize(&num, &size);
  if(size == 0)
    return -1;  // Failure

  pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
  if(pImageCodecInfo == NULL)
    return -1;  // Failure

  GetImageEncoders(num, size, pImageCodecInfo);

  for(UINT j = 0; j < num; ++j)
  {
    if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
    {
      *pClsid = pImageCodecInfo[j].Clsid;
      free(pImageCodecInfo);
      return j;  // Success
    }
  }

  free(pImageCodecInfo);
  return 0;
}

// Este es el metodo que tomo la captura.
// c es solo una variable que utilice para probar el
// metodo en un loop, la puede quitar y remplazar c
// por el log_sec_num.

inline void take_screenshot(const std::string & filename)
{
    using namespace Gdiplus;
    GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR gdiplusToken;
    GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

    {
        HDC scrdc, memdc;
        HBITMAP membit;
        scrdc = ::GetDC(0);
        int Height = GetSystemMetrics(SM_CYSCREEN);
        int Width = GetSystemMetrics(SM_CXSCREEN);
        memdc = CreateCompatibleDC(scrdc);
        membit = CreateCompatibleBitmap(scrdc, Width, Height);
        HBITMAP hOldBitmap =(HBITMAP) SelectObject(memdc, membit);
        BitBlt(memdc, 0, 0, Width, Height, scrdc, 0, 0, SRCCOPY);

        Gdiplus::Bitmap bitmap(membit, NULL);
        CLSID clsid;
        const char* name = filename.c_str();
        const size_t cSize = strlen(name)+1;
        wchar_t* wc = new wchar_t[cSize];
        mbstowcs (wc, name, cSize);
        GetEncoderClsid(L"image/png", &clsid);
        bitmap.Save(wc, &clsid,NULL);

        SelectObject(memdc, hOldBitmap);

        DeleteObject(memdc);

        DeleteObject(membit);

        ::ReleaseDC(0,scrdc);
    }

    GdiplusShutdown(gdiplusToken);
}

int main ()
{
    const std::string & filename = "C:\\Screenshot.png";
    take_screenshot(filename);
}

If try to get the entire screen but I end up with just have the picture. Can any one see where my error it's ??

    int Height = GetSystemMetrics(SM_CYSCREEN);

Quote from the MSDN docs: "The height of the screen of the primary display monitor". You got exactly what you asked for, the primary display is one of your monitors. The first one.

Use SM_CYVIRTUALSCREEN instead. Same for X.