Tk_FontId(3tk)

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NAME

       Tk_FontId,  Tk_GetFontMetrics,  Tk_PostscriptFontName  - accessor func-
       tions for fonts

SYNOPSIS

       #include <tk.h>

       Font
       Tk_FontId(tkfont)

       void
       Tk_GetFontMetrics(tkfont, fmPtr)

       int
       Tk_PostscriptFontName(tkfont, dsPtr)

ARGUMENTS

       Tk_Font          tkfont   (in)      Opaque font  token  being  queried.
                                           Must have been returned by a previ-
                                           ous call to Tk_GetFont.

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

       Tcl_DString      *dsPtr   (out)     Pointer    to    an     initialized
                                           Tcl_DString  to  which  the name of
                                           the  Postscript  font  that  corre-
                                           sponds  to tkfont will be appended.
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DESCRIPTION

       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  linespace  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  mul-
       tiple 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 terms ascent, descent, and
       linespace, used in font metrics.

       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 ``rea-
       sonable'' Postscript printer, the following screen font families should
       print correctly:

              Avant  Garde, Arial, Bookman, Courier, Courier New, Geneva, Hel-
              vetica, Monaco, New Century Schoolbook, New York, Palatino, Sym-
              bol, 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.

DATA STRUCTURES |

       The Tk_FontMetrics data  structure  is  used  by  Tk_GetFontMetrics  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 letter 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.

KEYWORDS

       font

Tk                                    8.0                         Tk_FontId(3)