takeScreenShot

unsigned int takeScreenShot(int startx, int starty,int endx,int endy, int skipPx, bool showPic){

        unsigned int ret = 0;

        HWND hDesktopWnd = NULL;
        HDC hDesktopDC = NULL;
        HDC hCaptureDC = NULL;
        HBITMAP hCaptureBitmap = NULL;

        hDesktopWnd = GetDesktopWindow();
        hDesktopDC = GetDC(hDesktopWnd);

        if (!hDesktopDC) {
                //MessageBox( NULL, L"no hdc screen!", L"Error", MB_OK|MB_ICONERROR);
                ret |= (unsigned char) 1;
                return ret;
        }

        hCaptureDC = CreateCompatibleDC(hDesktopDC);

        if (!hCaptureDC) {
                //MessageBox( NULL, L"no compatible dc screen!", L"Error", MB_OK|MB_ICONERROR);
                ret |= (unsigned char) 2;
                return ret;
        }

        hCaptureBitmap = CreateCompatibleBitmap(hDesktopDC, (endx - startx), (endy - starty));

        if (!hCaptureBitmap) {
                //MessageBox( NULL, L"no bitmap!", L"Error", MB_OK|MB_ICONERROR);
                ret |= (unsigned char) 3;
                return ret;
        }

        SelectObject(hCaptureDC, hCaptureBitmap);

        if(!BitBlt(hCaptureDC, 0, 0, (endx - startx), (endy - starty), hDesktopDC, startx, starty, SRCCOPY | CAPTUREBLT)){
                //MessageBox( NULL, L"BitBlt() failed", L"Error", MB_OK|MB_ICONERROR);
                ret |= (unsigned char) 4;
                return ret;
        }

        BITMAPFILEHEADER bmfHeader;
        BITMAPINFOHEADER bi;

        DWORD dwBmpSize = (endx - startx) * 3 * (endy - starty);

        bi.biSize = sizeof(BITMAPINFOHEADER);
        bi.biWidth = (endx - startx);
        bi.biHeight = (endy - starty);
        bi.biPlanes = 1;
        bi.biBitCount = 24;
        bi.biCompression = BI_RGB;
        bi.biSizeImage = 0;
        bi.biXPelsPerMeter = 0;
        bi.biYPelsPerMeter = 0;
        bi.biClrUsed = 0;
        bi.biClrImportant = 0;

        char *lpbitmap = new char[dwBmpSize];

        GetDIBits(hCaptureDC, hCaptureBitmap, 0, (UINT)(endy - starty), lpbitmap, (BITMAPINFO *)&bi, DIB_RGB_COLORS);

        unsigned char R = colAvr((unsigned char*)lpbitmap, COLOR_R, dwBmpSize, skipPx);
        unsigned char G = colAvr((unsigned char*)lpbitmap, COLOR_G, dwBmpSize, skipPx);
        unsigned char B = colAvr((unsigned char*)lpbitmap, COLOR_B, dwBmpSize, skipPx);

        ret = (R << 24);
        ret |= (G << 16);
        ret |= (B << 8);
        ret |= (unsigned char) 0;

        if(showPic){

                FILE *fp;
                errno_t err;

                if((err = fopen_s(&fp, "c:\\cica.bmp", "wb")) != NULL){
                        ret |= (unsigned char) 5;
                        return ret;
                }

                DWORD dwSizeofDIB = dwBmpSize + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
                bmfHeader.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER);
                bmfHeader.bfSize = dwSizeofDIB;
                bmfHeader.bfType = 0x4D42; //BM

                fwrite((unsigned char*)&bmfHeader, sizeof(unsigned char), sizeof(BITMAPFILEHEADER), fp);
                fwrite((unsigned char*)&bi, sizeof(unsigned char), sizeof(BITMAPINFOHEADER), fp);
                fwrite((unsigned char*)lpbitmap, sizeof(unsigned char), dwBmpSize, fp);

                fclose(fp);
        }

        delete lpbitmap;

        ReleaseDC(hDesktopWnd,hDesktopDC);
        DeleteDC(hCaptureDC);
        DeleteObject(hCaptureBitmap);

        return ret;
}