int SetTextCharacterExtra( int nCharExtra );
nCharExtra
Specifies the amount of extra space (in logical units) to be added to each character. If the current mapping mode is not MM_TEXT, nCharExtra is transformed and rounded to the nearest pixel.
Sets the amount of intercharacter spacing. GDI adds this spacing to each character, including break characters, when it writes a line of text to the device context.
The amount of the previous intercharacter spacing.
CDC::GetTextCharacterExtra, ::SetTextCharacterExtra