C / C++ / MFC

POINT pt = {10, 20}; // in logical coords
LPtoDP(&pt, 1);
// pt now contains converted device coords

char* data = new char[GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3];
BITMAPINFO BitmapInfo;
BITMAPFILEHEADER BFH;
memset(&BFH,0,sizeof(BITMAPFILEHEADER));
BFH.bfType = 'MB';
BFH.bfSize = sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3;
BFH.bfOffBits = sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER);
BITMAPINFOHEADER bitmapinfoheader;
bitmapinfoheader.biSize = sizeof(BITMAPINFOHEADER);
bitmapinfoheader.biWidth = GetSystemMetrics(SM_CXSCREEN);
bitmapinfoheader.biHeight = GetSystemMetrics(SM_CYSCREEN);
bitmapinfoheader.biPlanes = bitmapinfoheader.biBitCount = 24;
bitmapinfoheader.biCompression = 0;
bitmapinfoheader.biSizeImage = GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3;
bitmapinfoheader.biXPelsPerMeter = bitmapinfoheader.biYPelsPerMeter = bitmapinfoheader.biClrUsed =bitmapinfoheader.biClrImportant = 0;

HDC hDC = ::GetDC(NULL);
HDC hCompatibleDC = ::CreateCompatibleDC(hDC);
HBITMAP hBitmap =::CreateDIBSection(hCompatibleDC,&BitmapInfo,DIB_RGB_COLORS,(void**)data,NULL,NULL);
BitBlt(hDC,0,0,GetSystemMetrics(SM_CXSCREEN),GetSystemMetrics(SM_CYSCREEN),hCompatibleDC,0,0,SRCCOPY);
CFile file;
file.Open("New.bmp",CFile::modeWrite|CFile::modeCreate);
file.Write(&BFH,sizeof(BITMAPFILEHEADER));
file.Write(&bitmapinfoheader,sizeof(BITMAPINFOHEADER));
RGBQUAD rgb;
file.Write(&rgb,sizeof(RGBQUAD));
file.Write(data,GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3);
file.Close();