I'm building an application using the mfc wizard in visual c++ 6. I've set the document to the size of an a3 page which takes up more space than is available on screen. The x, y co-ordinates for the document are 1700, 1122. I've got an A3 touch pad with x, y co-ordinates of 2500, 2000 and I want to map the pad to the document. I've used this code to draw a rectangle on the screen:

void CProjectView::OnLButtonDown(UINT nFlags, CPoint point) {

CPoint AP;
CString showcoord;
char* s1 = new char[7];

_itoa(point.x, s1, 10);
showcoord += s1;
showcoord += " , ";
_itoa(point.y, s1, 10);
showcoord += s1;


if (drawpoint) {
CClientDC dc(this);
AP.x = (point.x)-20;
AP.y = (point.y)-20;
InfoPoint *Info = GetDocument()->AddPoint(point, AP);
Info->Draw(&dc);
AfxMessageBox(showcoord);

}
}

The AddPoint function draws the rectangle on the screen but the co-ordinates in the message box show the point co-ordinates for what can be seen on screen, not the whole document. eg. when I go the bottom-right hand corner and click, the co-ordinates pop up with 960, 620 instead of 1700, 1122. Do you know a way to return the document co-ordinate of the point clicked instead of the screen co-ordinate?