PBITMAPINFO CreateBitmapInfoStructure(HBITMAP hBmp)
{
BITMAP bmp;
PBITMAPINFO pbmi;
WORD cClrBits;

//obtiene la altura, anchura, y profundidad del color de la imagen
if(!GetObject(hBmp,sizeof(BITMAP),(LPSTR)&bmp))return NULL;

cClrBits = 24;

/*
reserva la memoria para la estructura PBITMAPINFO, que contendrá la informacion
de la cabecera
*/
if(cClrBits!=24)
pbmi=(PBITMAPINFO)LocalAlloc(LPTR,sizeof(BITMAPINFOHEADER)+sizeof(RGBQUAD)*(1<<cClrBits));
else
pbmi=(PBITMAPINFO)LocalAlloc(LPTR,sizeof(BITMAPINFOHEADER));

//inicializa la estructura
pbmi->bmiHeader.biSize = sizeof( BITMAPINFOHEADER );
pbmi->bmiHeader.biWidth = bmp.bmWidth;
pbmi->bmiHeader.biHeight = bmp.bmHeight;
pbmi->bmiHeader.biPlanes = bmp.bmPlanes;
pbmi->bmiHeader.biBitCount = 24;

if(cClrBits<24)pbmi->bmiHeader.biClrUsed=(1<<cClrBits);

pbmi->bmiHeader.biCompression = BI_RGB;
pbmi->bmiHeader.biSizeImage=(pbmi->bmiHeader.biWidth+7)/8*pbmi->bmiHeader.biHeight*cClrBits;
pbmi->bmiHeader.biClrImportant = 0;

return pbmi;
}

HRESULT SaveBitmap(char strFileName[128],PBITMAPINFO pbi,HBITMAP hBMP,HDC hDC)
{
HRESULT hr = E_FAIL;
HANDLE hf; // file handle
BITMAPFILEHEADER hdr; // bitmap file-header
PBITMAPINFOHEADER pbih; // bitmap info-header
LPBYTE lpBits; // memorypointer
DWORD dwTotal; // total count of bytes
DWORD cb; // incremental count of bytes
BYTE *hp; // byte pointer
DWORD dwTmp; // temp-variable


if(pbi==NULL)return E_FAIL;

pbih=(PBITMAPINFOHEADER)pbi;
lpBits=(LPBYTE)GlobalAlloc(GMEM_FIXED,pbih->biSizeImage);

if(!lpBits)return E_FAIL;

if(!GetDIBits(hDC,hBMP,0,(WORD)pbih->biHeight,lpBits,pbi,DIB_RGB_COLORS))return E_FAIL;

//crea el .bmp
hf=CreateFile(strFileName,GENERIC_READ|GENERIC_WRITE,(DWORD)0,NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,(HANDLE)NULL);

if(hf==INVALID_HANDLE_VALUE)return E_FAIL;

hdr.bfType = 0x4D42; // 0x42 = "B", 0x4D = "M"


hdr.bfSize=(DWORD)(sizeof(BITMAPFILEHEADER)+pbih->biSize+pbih->biClrUsed*sizeof(RGBQUAD)+pbih->biSizeImage);
hdr.bfReserved1=0;
hdr.bfReserved2=0;

hdr.bfOffBits=(DWORD)sizeof(BITMAPFILEHEADER)+pbih->biSize+pbih->biClrUsed*sizeof(RGBQUAD);


if(!WriteFile(hf,(LPVOID)&hdr,sizeof(BITMAPFILEHEADER),(LPDWORD)&dwTmp,NULL))return E_FAIL;

if(!WriteFile(hf,(LPVOID)pbih,sizeof(BITMAPINFOHEADER)+pbih->biClrUsed*sizeof(RGBQUAD),(LPDWORD)&dwTmp,(NULL)))return E_FAIL;


dwTotal=cb=pbih->biSizeImage;
hp=lpBits;

if(!WriteFile(hf,(LPSTR)hp,(int)cb,(LPDWORD)&dwTmp,NULL))return E_FAIL;
if(!CloseHandle(hf))return E_FAIL;

GlobalFree((HGLOBAL)lpBits);

return S_OK;
}

/*
uso: CapturaPantalla(posicion_inicial_x,posicion_inicial_y,posicion_final_x,posicion_final_y);
*/

void CapturaPantalla(unsigned int Ax,unsigned int Ay,unsigned int Bx,unsigned int By,char *Ruta)
{
BYTE *mem;
int bpp,c;
    HWND HwndSrc;
    HDC HdcSrc;
    HDC HdcMemory;
    HDC HdcStrech;
    HBITMAP Hbmp;
    HBITMAP HbmpStrech;
    HBITMAP HbmpPrev;
    HBITMAP HbmpPrevStrech;
    HBITMAP BmpPrueba;

HwndSrc=GetDesktopWindow();                               //almacena el manejador del escritorio
    HdcSrc=GetWindowDC(HwndSrc);                               //se obtiene el DC del escritorio
HdcMemory=CreateCompatibleDC(HdcSrc);                      //se crea una copia del DC del escritorio
HdcStrech=CreateCompatibleDC(HdcSrc);                   //Cd que almacenara la imagen pequeña
Hbmp=CreateCompatibleBitmap(HdcSrc,1024,768);          //se cra un bitmap del DC del escritorio
HbmpStrech=CreateCompatibleBitmap(HdcSrc,Bx-Ax,By-Ay);  //bitmap que almacenara el Strech
HbmpPrev=(HBITMAP)SelectObject(HdcMemory,Hbmp);        //se asocia el bitmap con el DC
HbmpPrevStrech=(HBITMAP)SelectObject(HdcStrech,HbmpStrech);

BitBlt(HdcMemory,0,0,800,600,HdcSrc,Ax,Ay,SRCCOPY);
    StretchBlt(HdcStrech,0,0,800,600,HdcMemory,0,0,800,600,SRCCOPY);
    HbmpStrech=(HBITMAP)SelectObject(HdcStrech,HbmpPrevStrech);
    Hbmp=(HBITMAP)SelectObject(HdcMemory,HbmpPrev);

bpp=800*600*8;

c=GetBitmapBits(HbmpStrech,0,0);
mem=(BYTE*)malloc((c-1)*sizeof(BYTE*));
memset(mem,0,sizeof(mem));

    GetBitmapBits(HbmpStrech,c,mem);
BmpPrueba = CreateCompatibleBitmap(HdcSrc,Bx-Ax,By-Ay);
SetBitmapBits(BmpPrueba,c,mem);
SaveBitmap(Ruta,CreateBitmapInfoStructure(BmpPrueba),BmpPrueba,HdcSrc);

    DeleteDC(HdcSrc);
    DeleteDC(HdcMemory);
    DeleteDC(HdcStrech);
    DeleteObject(Hbmp);
    DeleteObject(HbmpPrev);
    DeleteObject(HbmpStrech);
    DeleteObject(HbmpPrevStrech);

return;
}

#include <windows.h>
#include <iostream>
#include "captura.h"

using namespace std;

int main(int argc, char *argv[])
{
    char name[15];
    for(int i=0;i<10;i++)
    {
            name[0]='\0';
            strcat(name,"D:\\");
            char n[2];
            n[0]='\0';
            sprintf(n,"%i",i);
            strcat(name,n);
            strcat(name,".jpg");
    CapturaPantalla(0,0,800,600,name);
 Sleep(1000);
}
    system("PAUSE");
    return EXIT_SUCCESS;
}