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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.
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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 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)

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