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Tk_FontId(3)                                Tk Library Procedures                               Tk_FontId(3)



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NAME
       Tk_FontId, Tk_GetFontMetrics, Tk_PostscriptFontName - accessor 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 STRUCTURES below for details.

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

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 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
       terms ascent, descent, and linespace, used in font metrics.

       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 Ding-bats. Dingbats.
              bats.

       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                                                   8.0                                        Tk_FontId(3)