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'\" Copyright (c) 1996 Sun Microsystems, Inc.

'\"

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'\" RCS: @(#) $Id: FontId.3,v 1.1.1.1 2002-01-16 10:25:48 markom Exp $

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.so man.macros

.TH Tk_FontId 3 8.0 Tk "Tk Library Procedures"

.BS

.SH NAME

Tk_FontId, Tk_FontMetrics, Tk_PostscriptFontName \- accessor functions for

fonts

.SH SYNOPSIS

.nf

\fB#include \fR

.sp

Font

\fBTk_FontId(\fItkfont\fB)\fR

.sp

void

\fBTk_GetFontMetrics(\fItkfont, fmPtr\fB)\fR

.sp

int

\fBTk_PostscriptFontName(\fItkfont, dsPtr\fB)\fR

.SH ARGUMENTS

.AS Tk_FontMetrics *dsPtr

.AP Tk_Font tkfont in

Opaque font token being queried.  Must have been returned by a previous

call to \fBTk_GetFont\fR.

.AP Tk_FontMetrics *fmPtr out

Pointer to structure in which the font metrics for \fItkfont\fR will

be stored.

.AP Tcl_DString *dsPtr out

Pointer to an initialized \fBTcl_DString\fR to which the name of the

Postscript font that corresponds to \fItkfont\fR will be appended.

.BE

.SH DESCRIPTION

.PP

Given a \fItkfont\fR, \fBTk_FontId\fR 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.

.PP

\fBTk_GetFontMetrics\fR computes the ascent, descent, and linespace of the

\fItkfont\fR in pixels and stores those values in the structure pointer to by

\fIfmPtr\fR.  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 \fBfont\fR command for definitions of the terms

ascent, descent, and linespace, used in font metrics.

.PP

\fBTk_PostscriptFontName\fR maps a \fItkfont\fR to the corresponding

Postcript font name that should be used when printing.  The return value

is the size in points of the \fItkfont\fR and the Postscript font name is

appended to \fIdsPtr\fR.  \fIDsPtr\fR must refer to an initialized

\fBTcl_DString\fR.  Given a ``reasonable'' Postscript printer, the

following screen font families should print correctly:

.IP

\fBAvant Garde\fR, \fBArial\fR, \fBBookman\fR, \fBCourier\fR,

\fBCourier New\fR, \fBGeneva\fR, \fBHelvetica\fR, \fBMonaco\fR,

\fBNew Century Schoolbook\fR, \fBNew York\fR, \fBPalatino\fR, \fBSymbol\fR,

\fBTimes\fR, \fBTimes New Roman\fR, \fBZapf Chancery\fR, and

\fBZapf Dingbats\fR.

.PP

Any other font families may not print correctly because the computed

Postscript font name may be incorrect or not exist on the printer.

.VS 8.0 br

.SH DATA STRUCTURES

The Tk_FontMetrics data structure is used by Tk_GetFontMetrics to return

information about a font and is defined as follows:

.CS

typedef struct Tk_FontMetrics {

    int ascent;

    int descent;

    int linespace;

} Tk_FontMetrics;

.CE

The \fIlinespace\fR 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.

.PP

The \fIdescent\fR 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.

.PP

The \fIlinespace\fR 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.

.VE

.SH KEYWORDS

font