一、Canvas:

String s1="发的是浪费空间";
Canvas->Font->Color=clRed;
Canvas->Font->Name="微软雅黑";
Canvas->Font->Size=24;
 
int width=Canvas->TextWidth(s1);//是的 你获取了当前字体下该字符串的宽度
int height=Canvas->TextHeight(s2);//是的 你获取了当前字体下该字符串的高度

二、API:

BOOL   GetCharWidth( 

        HDC   hdc, //   handle   of   device   context   
        UINT   iFirstChar, //   first   character   in   range   to   query     
        UINT   iLastChar, //   last   character   in   range   to   query   
        LPINT   lpBuffer   //   address   of   buffer   for   widths   
      );