Uses the output device context, m_hDC, and retrieves the widths of individual characters in a consecutive group of characters from the current font.
For example, if nFirstChar identifies the letter 'a' and nLastChar identifies the letter 'z', the function retrieves the widths of all lowercase characters.
The function stores the values in the buffer pointed to by lpBuffer. This buffer must be large enough to hold all of the widths; that is, there must be at least 26 entries in the example given.
If a character in the consecutive group of characters does not exist in a particular font, it will be assigned the width value of the default character.