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Tk_FontId(3tk) Tk Library Procedures Tk_FontId(3tk) 





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
      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.






SEE ALSO


font(3tk), MeasureChar(3tk)






KEYWORDS


font, measurement, Postscript







  

    8.0
    Tk