Tk_FontId(3)

Tk_FontId(3)          Tk Library Procedures          Tk_FontId(3)

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NAME

     Tk_FontId, Tk_GetFontMetrics, Tk_PostscriptFontName - acces-
     sor functions for fonts

SYNOPSIS

     #include <tk.h>

     Font
     Tk_FontId(tkfont)

     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  previous
                                         call to Tk_GetFont.

     Tk_FontMetrics *fmPtr (out)         Pointer to structure  in
                                         which  the  font metrics
                                         for   tkfont   will   be
                                         stored.  See DATA STRUC-
                                         TURES below for details.

     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.
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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 speci-
     fied 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 multiple lines of text, to
     align the baselines of text in different fonts, and to vert-
     ically  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                      Last change: 8.0                        1

Tk_FontId(3)          Tk Library Procedures          Tk_FontId(3)

     Tk_PostscriptFontName maps a  tkfont  to  the  corresponding
     Postscript 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   "reasonable"
     Postscript  printer,  the  following  screen  font  families
     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.

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 ascent 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.

SEE ALSO

     font(n), MeasureChar(3)

KEYWORDS

     font, measurement, Postscript

Tk                      Last change: 8.0                        2