The CSize class is similar to the Windows SIZE structure, which implements a relative coordinate or position.
A SIZE structure has the following form:
typedef struct tagSIZE {
int cx;
int cy;
} SIZE;
The cx and cy members of CSize are public. In addition, CSize implements member functions to manipulate the SIZE structure.
Because CSize derives from tagSIZE, CSize objects may be used as SIZE structures.
CRect, CPoint