Ubuntu Manpage: Tk_FontId, Tk_GetFontMetrics, Tk_PostscriptFontName

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.
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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
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 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 {
                  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.

KEYWORDS