'\"
'\" Copyright (c) 1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: FontId.3,v 1.3 2000/07/25 21:14:34 jenglish Exp $
'\" 
'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
'\"
'\" .AP type name in/out ?indent?
'\"	Start paragraph describing an argument to a library procedure.
'\"	type is type of argument (int, etc.), in/out is either "in", "out",
'\"	or "in/out" to describe whether procedure reads or modifies arg,
'\"	and indent is equivalent to second arg of .IP (shouldn't ever be
'\"	needed;  use .AS below instead)
'\"
'\" .AS ?type? ?name?
'\"	Give maximum sizes of arguments for setting tab stops.  Type and
'\"	name are examples of largest possible arguments that will be passed
'\"	to .AP later.  If args are omitted, default tab stops are used.
'\"
'\" .BS
'\"	Start box enclosure.  From here until next .BE, everything will be
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'\"
'\" .BE
'\"	End of box enclosure.
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'\"	Begin code excerpt.
'\"
'\" .CE
'\"	End code excerpt.
'\"
'\" .VS ?version? ?br?
'\"	Begin vertical sidebar, for use in marking newly-changed parts
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'\"	found and removed when they reach a certain age.  If another argument
'\"	is present, then a line break is forced before starting the sidebar.
'\"
'\" .VE
'\"	End of vertical sidebar.
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'\" .DS
'\"	Begin an indented unfilled display.
'\"
'\" .DE
'\"	End of indented unfilled display.
'\"
'\" .SO
'\"	Start of list of standard options for a Tk widget.  The
'\"	options follow on successive lines, in four columns separated
'\"	by tabs.
'\"
'\" .SE
'\"	End of list of standard options for a Tk widget.
'\"
'\" .OP cmdName dbName dbClass
'\"	Start of description of a specific option.  cmdName gives the
'\"	option's name as specified in the class command, dbName gives
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'\"
'\" .UL arg1 arg2
'\"	Print arg1 underlined, then print arg2 normally.
'\"
'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
'\"
'\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
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.ie !"\\$4"" .TP \\$4
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.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
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.\"	Draw four-sided box normally, but don't draw top of
.\"	box if the box started on an earlier page.
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.\}
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\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
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'\"	# page bottom macro.
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.ev 2
'ti 0
'nf
.mk ^t
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.\"	draw two sides but no top otherwise.
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..
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.sp
..
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.nf
.ta 5.5c 11c
.ft B
..
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.de SE
.fi
.ft R
.LP
See the \\fBoptions\\fR manual entry for details on the standard options.
..
'\"	# OP - start of full description for a single option
.de OP
.LP
.nf
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Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
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..
'\"	# CS - begin code excerpt
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\\$1\l'|0\(ul'\\$2
..
.TH Tk_FontId 3 8.0 Tk "Tk Library Procedures"
.BS
.SH NAME
Tk_FontId, Tk_GetFontMetrics, Tk_PostscriptFontName \- accessor functions for 
fonts
.SH SYNOPSIS
.nf
\fB#include <tk.h>\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