Call this member function to use the output device context, m_hDC, and compute the width and height of a line of text, using the current font.
Points to a string of characters. You can also pass a CString object for this parameter.
Specifies the number of characters in the string. If nCount is –1, the length is calculated.
A CString object that contains the specified characters to be measured.
The current clipping region does not affect the width and height returned by GetOutputTextExtent.
Since some devices do not place characters in regular cell arrays (that is, they carry out kerning), the sum of the extents of the characters in a string may not be equal to the extent of the string.