Tk_FontId,  Tk_FontMetrics, Tk_PostscriptFontName - acces­
       sor functions for fonts


       #include <tk.h>


       Tk_GetFontMetrics(tkfont, fmPtr)

       Tk_PostscriptFontName(tkfont, dsPtr)


       Tk_Font          tkfont   (in)      Opaque   font    token
                                           being  queried.   Must
                                           have been returned  by
                                           a   previous  call  to

       Tk_FontMetrics   *fmPtr   (out)     Pointer  to  structure
                                           in which the font met­
                                           rics for  tkfont  will
                                           be stored.

       Tcl_DString      *dsPtr   (out)     Pointer to an initial­
                                           ized  Tcl_DString   to
                                           which  the name of the
                                           Postscript  font  that
                                           corresponds  to tkfont
                                           will be appended.


       Given a tkfont, Tk_FontId returns the token that should be
       selected into an XGCValues structure in order to construct
       a graphics context that can be used to draw  text  in  the
       specified font.

       Tk_GetFontMetrics computes the ascent, descent, and lines­
       pace of the tkfont in pixels and stores  those  values  in
       the  structure  pointer  to by fmPtr.  These values can be
       used in computations such as to space  multiple  lines  of
       text,  to  align the baselines of text in different fonts,
       and to vertically align text in a given region.   See  the
       documentation  for the font command for definitions of the

       Tk_PostscriptFontName  maps  a tkfont to the corresponding
       Postcript font name that should  be  used  when  printing.
       The  return  value is the size in points of the tkfont and
       the Postscript font name is appended to dsPtr.  DsPtr must
       refer  to  an  initialized Tcl_DString.  Given a ``reason­
       able'' Postscript printer, the following screen font fami­
       lies should print correctly:

              Avant  Garde, Arial, Bookman, Courier, Courier New,
              Geneva, Helvetica, Monaco, New Century  Schoolbook,
              New York, Palatino, Symbol, Times, Times New Roman,
              Zapf Chancery, and Zapf Dingbats.

       Any other font families may not  print  correctly  because
       the  computed Postscript font name may be incorrect or not
       exist on the printer.


       The Tk_FontMetrics data structure is used  by  Tk_GetFont­ |
       Metrics  to return information about a font and is defined |
       as follows:                                                |
              typedef struct Tk_FontMetrics {                     |
                  int ascent;                                     |
                  int descent;                                    |
                  int linespace;                                  |
              } Tk_FontMetrics;                                   |
       The linespace field is  the  amount  in  pixels  that  the |
       tallest  letter  sticks  up  above  the baseline, plus any |
       extra blank space added by the designer of the font.       |

       The descent is the largest amount in pixels that any  let­ |
       ter  sticks below the baseline, plus any extra blank space |
       added by the designer of the font.                         |

       The linespace is the sum of the ascent and  descent.   How |
       far  apart  two  lines  of text in the same font should be |
       placed so that none of the characters in one line  overlap |
       any of the characters in the other line.