95 lines
3.4 KiB
Groff
95 lines
3.4 KiB
Groff
'\"
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'\" Copyright (c) 1996 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH Tk_FontId 3 8.0 Tk "Tk Library Procedures"
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.so man.macros
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.BS
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.SH NAME
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Tk_FontId, Tk_GetFontMetrics, Tk_PostscriptFontName \- accessor functions for
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fonts
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.SH SYNOPSIS
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.nf
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\fB#include <tk.h>\fR
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.sp
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Font
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\fBTk_FontId(\fItkfont\fB)\fR
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.sp
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\fBTk_GetFontMetrics(\fItkfont, fmPtr\fB)\fR
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.sp
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int
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\fBTk_PostscriptFontName(\fItkfont, dsPtr\fB)\fR
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.SH ARGUMENTS
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.AS Tk_FontMetrics *dsPtr
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.AP Tk_Font tkfont in
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Opaque font token being queried. Must have been returned by a previous
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call to \fBTk_GetFont\fR.
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.AP Tk_FontMetrics *fmPtr out
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Pointer to structure in which the font metrics for \fItkfont\fR will
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be stored. See \fBDATA STRUCTURES\fR below for details.
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.AP Tcl_DString *dsPtr out
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Pointer to an initialized \fBTcl_DString\fR to which the name of the
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Postscript font that corresponds to \fItkfont\fR will be appended.
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.BE
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.SH DESCRIPTION
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.PP
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Given a \fItkfont\fR, \fBTk_FontId\fR returns the token that should be
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selected into an XGCValues structure in order to construct a graphics
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context that can be used to draw text in the specified font.
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.PP
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\fBTk_GetFontMetrics\fR computes the ascent, descent, and linespace of the
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\fItkfont\fR in pixels and stores those values in the structure pointer to by
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\fIfmPtr\fR. These values can be used in computations such as to space
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multiple lines of text, to align the baselines of text in different
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fonts, and to vertically align text in a given region. See the
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documentation for the \fBfont\fR command for definitions of the terms
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ascent, descent, and linespace, used in font metrics.
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.PP
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\fBTk_PostscriptFontName\fR maps a \fItkfont\fR to the corresponding
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Postscript font name that should be used when printing. The return value
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is the size in points of the \fItkfont\fR and the Postscript font name is
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appended to \fIdsPtr\fR. \fIDsPtr\fR must refer to an initialized
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\fBTcl_DString\fR. Given a
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.QW reasonable
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Postscript printer, the
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following screen font families should print correctly:
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.IP
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\fBAvant Garde\fR, \fBArial\fR, \fBBookman\fR, \fBCourier\fR,
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\fBCourier New\fR, \fBGeneva\fR, \fBHelvetica\fR, \fBMonaco\fR,
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\fBNew Century Schoolbook\fR, \fBNew York\fR, \fBPalatino\fR, \fBSymbol\fR,
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\fBTimes\fR, \fBTimes New Roman\fR, \fBZapf Chancery\fR, and
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\fBZapf Dingbats\fR.
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.PP
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Any other font families may not print correctly because the computed
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Postscript font name may be incorrect or not exist on the printer.
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.SH "DATA STRUCTURES"
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.PP
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The \fBTk_FontMetrics\fR data structure is used by \fBTk_GetFontMetrics\fR to
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return information about a font and is defined as follows:
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.CS
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typedef struct Tk_FontMetrics {
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int \fIascent\fR;
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int \fIdescent\fR;
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int \fIlinespace\fR;
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} \fBTk_FontMetrics\fR;
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.CE
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.PP
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The \fIascent\fR field is the amount in pixels that the tallest
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letter sticks up above the baseline, plus any extra blank space added
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by the designer of the font.
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.PP
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The \fIdescent\fR is the largest amount in pixels that any letter
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sticks below the baseline, plus any extra blank space added by the
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designer of the font.
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.PP
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The \fIlinespace\fR is the sum of the ascent and descent. How far
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apart two lines of text in the same font should be placed so that none
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of the characters in one line overlap any of the characters in the
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other line.
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.SH "SEE ALSO"
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font(n), MeasureChar(3)
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.SH KEYWORDS
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font, measurement, Postscript
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