Tk_FontId(3) Tk (8.0) Tk_FontId(3)
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NAME
Tk_FontId, Tk_FontMetrics, Tk_PostscriptFontName - accessor
functions for fonts
SYNOPSIS
#include <tk.h>
Font
Tk_FontId(tkfont)
void
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.
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
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Tk_FontId(3) Tk (8.0) Tk_FontId(3)
terms ascent, descent, and linespace, used in font metrics.
Tk_PostscriptFontName maps a tkfont to the corresponding
Postcript 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 linespace 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
font
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