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)