man/man3/MeasureChar.3 - toolchains/skids - Git at Google

 '\"
 '\" 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: MeasureChar.3,v 1.4 1999/12/21 23:54:17 hobbs 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
 '\"	enclosed in one large box.
 '\"
 '\" .BE
 '\"	End of box enclosure.
 '\"
 '\" .CS
 '\"	Begin code excerpt.
 '\"
 '\" .CE
 '\"	End code excerpt.
 '\"
 '\" .VS ?version? ?br?
 '\"	Begin vertical sidebar, for use in marking newly-changed parts
 '\"	of man pages.  The first argument is ignored and used for recording
 '\"	the version when the .VS was added, so that the sidebars can be
 '\"	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.
 '\"
 '\" .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
 '\"	the option's name in the option database, and dbClass gives
 '\"	the option's class in the option database.
 '\"
 '\" .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
 '\"	# Start an argument description
 .de AP
 .ie !"\\$4"" .TP \\$4
 .el \{\
 .   ie !"\\$2"" .TP \\n()Cu
 .   el          .TP 15
 .\}
 .ta \\n()Au \\n()Bu
 .ie !"\\$3"" \{\
 \&\\$1	\\fI\\$2\\fP	(\\$3)
 .\".b
 .\}
 .el \{\
 .br
 .ie !"\\$2"" \{\
 \&\\$1	\\fI\\$2\\fP
 .\}
 .el \{\
 \&\\fI\\$1\\fP
 .\}
 .\}
 ..
 '\"	# define tabbing values for .AP
 .de AS
 .nr )A 10n
 .if !"\\$1"" .nr )A \\w'\\$1'u+3n
 .nr )B \\n()Au+15n
 .\"
 .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
 '\"	# BS - start boxed text
 '\"	# ^y = starting y location
 '\"	# ^b = 1
 .de BS
 .br
 .mk ^y
 .nr ^b 1u
 .if n .nf
 .if n .ti 0
 .if n \l'\\n(.lu\(ul'
 .if n .fi
 ..
 '\"	# BE - end boxed text (draw box now)
 .de BE
 .nf
 .ti 0
 .mk ^t
 .ie n \l'\\n(^lu\(ul'
 .el \{\
 .\"	Draw four-sided box normally, but don't draw top of
 .\"	box if the box started on an earlier page.
 .ie !\\n(^b-1 \{\
 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
 .\}
 .el \}\
 \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
 .\}
 .\}
 .fi
 .br
 .nr ^b 0
 ..
 '\"	# VS - start vertical sidebar
 '\"	# ^Y = starting y location
 '\"	# ^v = 1 (for troff;  for nroff this doesn't matter)
 .de VS
 .if !"\\$2"" .br
 .mk ^Y
 .ie n 'mc \s12\(br\s0
 .el .nr ^v 1u
 ..
 '\"	# VE - end of vertical sidebar
 .de VE
 .ie n 'mc
 .el \{\
 .ev 2
 .nf
 .ti 0
 .mk ^t
 \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
 .sp -1
 .fi
 .ev
 .\}
 .nr ^v 0
 ..
 '\"	# Special macro to handle page bottom:  finish off current
 '\"	# box/sidebar if in box/sidebar mode, then invoked standard
 '\"	# page bottom macro.
 .de ^B
 .ev 2
 'ti 0
 'nf
 .mk ^t
 .if \\n(^b \{\
 .\"	Draw three-sided box if this is the box's first page,
 .\"	draw two sides but no top otherwise.
 .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
 .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
 .\}
 .if \\n(^v \{\
 .nr ^x \\n(^tu+1v-\\n(^Yu
 \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
 .\}
 .bp
 'fi
 .ev
 .if \\n(^b \{\
 .mk ^y
 .nr ^b 2
 .\}
 .if \\n(^v \{\
 .mk ^Y
 .\}
 ..
 '\"	# DS - begin display
 .de DS
 .RS
 .nf
 .sp
 ..
 '\"	# DE - end display
 .de DE
 .fi
 .RE
 .sp
 ..
 '\"	# SO - start of list of standard options
 .de SO
 .SH "STANDARD OPTIONS"
 .LP
 .nf
 .ta 5.5c 11c
 .ft B
 ..
 '\"	# SE - end of list of standard options
 .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
 .ta 4c
 Command-Line Name:	\\fB\\$1\\fR
 Database Name:	\\fB\\$2\\fR
 Database Class:	\\fB\\$3\\fR
 .fi
 .IP
 ..
 '\"	# CS - begin code excerpt
 .de CS
 .RS
 .nf
 .ta .25i .5i .75i 1i
 ..
 '\"	# CE - end code excerpt
 .de CE
 .fi
 .RE
 ..
 .de UL
 \\$1\l'|0\(ul'\\$2
 ..
 .TH Tk_MeasureChars 3 8.1 Tk "Tk Library Procedures"
 .BS
 .SH NAME
 Tk_MeasureChars, Tk_TextWidth, Tk_DrawChars, Tk_UnderlineChars \- routines to measure and display simple single-line strings.
 .SH SYNOPSIS
 .nf
 \fB#include <tk.h>\fR
 .sp
 int
 \fBTk_MeasureChars(\fItkfont, string, numBytes, maxPixels, flags, lengthPtr\fB)\fR
 .sp
 int
 \fBTk_TextWidth(\fItkfont, string, numBytes\fB)\fR
 .sp
 void
 \fBTk_DrawChars(\fIdisplay, drawable, gc, tkfont, string, numBytes, x, y\fB)\fR
 .sp
 void
 \fBTk_UnderlineChars(\fIdisplay, drawable, gc, tkfont, string, x, y, firstByte, lastByte\fB)\fR
 .sp
 .SH ARGUMENTS
 .AS "const char" firstChar
 .AP Tk_Font tkfont in
 Token for font in which text is to be drawn or measured.  Must have been
 returned by a previous call to \fBTk_GetFont\fR.
 .AP "const char" *string in
 Text to be measured or displayed.  Need not be null terminated.  Any
 non-printing meta-characters in the string (such as tabs, newlines, and
 other control characters) will be measured or displayed in a
 platform-dependent manner.
 .VS 8.1
 .AP int numBytes in
 The maximum number of bytes to consider when measuring or drawing
 \fIstring\fR.  Must be greater than or equal to 0.
 .VE 8.1
 .AP int maxPixels in
 If \fImaxPixels\fR is >= 0, it specifies the longest permissible
 line length in pixels.  Characters from \fIstring\fR are processed only
 until this many pixels have been covered.  If \fImaxPixels\fR is < 0, then
 the line length is unbounded and the \fIflags\fR argument is ignored.
 .AP int flags in
 Various flag bits OR-ed together: TK_PARTIAL_OK means include a character
 as long as any part of it fits in the length given by \fImaxPixels\fR;
 otherwise, a character must fit completely to be considered.
 TK_WHOLE_WORDS means stop on a word boundary, if possible.  If
 TK_AT_LEAST_ONE is set, it means return at least one character even if no
 characters could fit in the length given by \fImaxPixels\fR.  If
 TK_AT_LEAST_ONE is set and TK_WHOLE_WORDS is also set, it means that if
 not even one word fits on the line, return the first few letters of the
 word that did fit; if not even one letter of the word fit, then the first
 letter will still be returned.
 .AP int *lengthPtr out
 Filled with the number of pixels occupied by the number of characters
 returned as the result of \fBTk_MeasureChars\fR.
 .AP Display *display in
 Display on which to draw.
 .AP Drawable drawable in
 Window or pixmap in which to draw.
 .AP GC gc in
 Graphics context for drawing characters.  The font selected into this GC
 must be the same as the \fItkfont\fR.
 .AP int "x, y" in
 Coordinates at which to place the left edge of the baseline when displaying
 \fIstring\fR.
 .VS 8.1
 .AP int firstByte in
 The index of the first byte of the first character to underline in the
 \fIstring\fR.  Underlining begins at the left edge of this character.
 .AP int lastByte in
 The index of the first byte of the last character up to which the
 underline will be drawn.  The character specified by \fIlastByte\fR
 will not itself be underlined.
 .VE 8.1
 .BE

 .SH DESCRIPTION
 .PP
 These routines are for measuring and displaying simple single-font,
 single-line, strings.  To measure and display single-font, multi-line,
 justified text, refer to the documentation for \fBTk_ComputeTextLayout\fR.
 There is no programming interface in the core of Tk that supports
 multi-font, multi-line text; support for that behavior must be built on
 top of simpler layers.
 .VS 8.1
 Note that the interfaces described here are
 byte-oriented not character-oriented, so index values coming from Tcl
 scripts need to be converted to byte offsets using the
 \fBTcl_UtfAtIndex\fR and related routines.
 .VE 8.1
 .PP
 A glyph is the displayable picture of a letter, number, or some other
 symbol.  Not all character codes in a given font have a glyph.
 Characters such as tabs, newlines/returns, and control characters that
 have no glyph are measured and displayed by these procedures in a
 platform-dependent manner; under X, they are replaced with backslashed
 escape sequences, while under Windows and Macintosh hollow or solid boxes
 may be substituted.  Refer to the documentation for
 \fBTk_ComputeTextLayout\fR for a programming interface that supports the
 platform-independent expansion of tab characters into columns and
 newlines/returns into multi-line text.
 .PP
 \fBTk_MeasureChars\fR is used both to compute the length of a given
 string and to compute how many characters from a string fit in a given
 amount of space.  The return value is the number of bytes from
 \fIstring\fR that fit in the space specified by \fImaxPixels\fR subject to
 the conditions described by \fIflags\fR.  If all characters fit, the return
 value will be \fInumBytes\fR.  \fI*lengthPtr\fR is filled with the computed
 width, in pixels, of the portion of the string that was measured.  For
 example, if the return value is 5, then \fI*lengthPtr\fR is filled with the
 distance between the left edge of \fIstring\fR[0] and the right edge of
 \fIstring\fR[4].
 .PP
 \fBTk_TextWidth\fR is a wrapper function that provides a simpler interface
 to the \fBTk_MeasureChars\fR function.  The return value is how much
 space in pixels the given \fIstring\fR needs.
 .PP
 \fBTk_DrawChars\fR draws the \fIstring\fR at the given location in the
 given \fIdrawable\fR.
 .PP
 \fBTk_UnderlineChars\fR underlines the given range of characters in the
 given \fIstring\fR.  It doesn't draw the characters (which are assumed to
 have been displayed previously by \fBTk_DrawChars\fR); it just draws the
 underline.  This procedure is used to underline a few characters without
 having to construct an underlined font.  To produce natively underlined
 text, the appropriate underlined font should be constructed and used.

 .SH KEYWORDS
 font
	'\"
	'\" 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: MeasureChar.3,v 1.4 1999/12/21 23:54:17 hobbs 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
	'\" enclosed in one large box.
	'\"
	'\" .BE
	'\" End of box enclosure.
	'\"
	'\" .CS
	'\" Begin code excerpt.
	'\"
	'\" .CE
	'\" End code excerpt.
	'\"
	'\" .VS ?version? ?br?
	'\" Begin vertical sidebar, for use in marking newly-changed parts
	'\" of man pages. The first argument is ignored and used for recording
	'\" the version when the .VS was added, so that the sidebars can be
	'\" 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.
	'\"
	'\" .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
	'\" the option's name in the option database, and dbClass gives
	'\" the option's class in the option database.
	'\"
	'\" .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
	'\" # Start an argument description
	.de AP
	.ie !"\\$4"" .TP \\$4
	.el \{\
	. ie !"\\$2"" .TP \\n()Cu
	. el .TP 15
	.\}
	.ta \\n()Au \\n()Bu
	.ie !"\\$3"" \{\
	\&\\$1 \\fI\\$2\\fP (\\$3)
	.\".b
	.\}
	.el \{\
	.br
	.ie !"\\$2"" \{\
	\&\\$1 \\fI\\$2\\fP
	.\}
	.el \{\
	\&\\fI\\$1\\fP
	.\}
	.\}
	..
	'\" # define tabbing values for .AP
	.de AS
	.nr )A 10n
	.if !"\\$1"" .nr )A \\w'\\$1'u+3n
	.nr )B \\n()Au+15n
	.\"
	.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
	'\" # BS - start boxed text
	'\" # ^y = starting y location
	'\" # ^b = 1
	.de BS
	.br
	.mk ^y
	.nr ^b 1u
	.if n .nf
	.if n .ti 0
	.if n \l'\\n(.lu\(ul'
	.if n .fi
	..
	'\" # BE - end boxed text (draw box now)
	.de BE
	.nf
	.ti 0
	.mk ^t
	.ie n \l'\\n(^lu\(ul'
	.el \{\
	.\" Draw four-sided box normally, but don't draw top of
	.\" box if the box started on an earlier page.
	.ie !\\n(^b-1 \{\
	\h'-1.5n'\L'\|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
	.\}
	.el \}\
	\h'-1.5n'\L'\|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
	.\}
	.\}
	.fi
	.br
	.nr ^b 0
	..
	'\" # VS - start vertical sidebar
	'\" # ^Y = starting y location
	'\" # ^v = 1 (for troff; for nroff this doesn't matter)
	.de VS
	.if !"\\$2"" .br
	.mk ^Y
	.ie n 'mc \s12\(br\s0
	.el .nr ^v 1u
	..
	'\" # VE - end of vertical sidebar
	.de VE
	.ie n 'mc
	.el \{\
	.ev 2
	.nf
	.ti 0
	.mk ^t
	\h'\|\\n(^lu+3n'\L'\|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-\|\\n(^lu+3n'
	.sp -1
	.fi
	.ev
	.\}
	.nr ^v 0
	..
	'\" # Special macro to handle page bottom: finish off current
	'\" # box/sidebar if in box/sidebar mode, then invoked standard
	'\" # page bottom macro.
	.de ^B
	.ev 2
	'ti 0
	'nf
	.mk ^t
	.if \\n(^b \{\
	.\" Draw three-sided box if this is the box's first page,
	.\" draw two sides but no top otherwise.
	.ie !\\n(^b-1 \h'-1.5n'\L'\|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'\|0u'\c
	.el \h'-1.5n'\L'\|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'\|0u'\c
	.\}
	.if \\n(^v \{\
	.nr ^x \\n(^tu+1v-\\n(^Yu
	\kx\h'-\\nxu'\h'\|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'\|0u'\c
	.\}
	.bp
	'fi
	.ev
	.if \\n(^b \{\
	.mk ^y
	.nr ^b 2
	.\}
	.if \\n(^v \{\
	.mk ^Y
	.\}
	..
	'\" # DS - begin display
	.de DS
	.RS
	.nf
	.sp
	..
	'\" # DE - end display
	.de DE
	.fi
	.RE
	.sp
	..
	'\" # SO - start of list of standard options
	.de SO
	.SH "STANDARD OPTIONS"
	.LP
	.nf
	.ta 5.5c 11c
	.ft B
	..
	'\" # SE - end of list of standard options
	.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
	.ta 4c
	Command-Line Name: \\fB\\$1\\fR
	Database Name: \\fB\\$2\\fR
	Database Class: \\fB\\$3\\fR
	.fi
	.IP
	..
	'\" # CS - begin code excerpt
	.de CS
	.RS
	.nf
	.ta .25i .5i .75i 1i
	..
	'\" # CE - end code excerpt
	.de CE
	.fi
	.RE
	..
	.de UL
	\\$1\l'\|0\(ul'\\$2
	..
	.TH Tk_MeasureChars 3 8.1 Tk "Tk Library Procedures"
	.BS
	.SH NAME
	Tk_MeasureChars, Tk_TextWidth, Tk_DrawChars, Tk_UnderlineChars \- routines to measure and display simple single-line strings.
	.SH SYNOPSIS
	.nf
	\fB#include <tk.h>\fR
	.sp
	int
	\fBTk_MeasureChars(\fItkfont, string, numBytes, maxPixels, flags, lengthPtr\fB)\fR
	.sp
	int
	\fBTk_TextWidth(\fItkfont, string, numBytes\fB)\fR
	.sp
	void
	\fBTk_DrawChars(\fIdisplay, drawable, gc, tkfont, string, numBytes, x, y\fB)\fR
	.sp
	void
	\fBTk_UnderlineChars(\fIdisplay, drawable, gc, tkfont, string, x, y, firstByte, lastByte\fB)\fR
	.sp
	.SH ARGUMENTS
	.AS "const char" firstChar
	.AP Tk_Font tkfont in
	Token for font in which text is to be drawn or measured. Must have been
	returned by a previous call to \fBTk_GetFont\fR.
	.AP "const char" *string in
	Text to be measured or displayed. Need not be null terminated. Any
	non-printing meta-characters in the string (such as tabs, newlines, and
	other control characters) will be measured or displayed in a
	platform-dependent manner.
	.VS 8.1
	.AP int numBytes in
	The maximum number of bytes to consider when measuring or drawing
	\fIstring\fR. Must be greater than or equal to 0.
	.VE 8.1
	.AP int maxPixels in
	If \fImaxPixels\fR is >= 0, it specifies the longest permissible
	line length in pixels. Characters from \fIstring\fR are processed only
	until this many pixels have been covered. If \fImaxPixels\fR is < 0, then
	the line length is unbounded and the \fIflags\fR argument is ignored.
	.AP int flags in
	Various flag bits OR-ed together: TK_PARTIAL_OK means include a character
	as long as any part of it fits in the length given by \fImaxPixels\fR;
	otherwise, a character must fit completely to be considered.
	TK_WHOLE_WORDS means stop on a word boundary, if possible. If
	TK_AT_LEAST_ONE is set, it means return at least one character even if no
	characters could fit in the length given by \fImaxPixels\fR. If
	TK_AT_LEAST_ONE is set and TK_WHOLE_WORDS is also set, it means that if
	not even one word fits on the line, return the first few letters of the
	word that did fit; if not even one letter of the word fit, then the first
	letter will still be returned.
	.AP int *lengthPtr out
	Filled with the number of pixels occupied by the number of characters
	returned as the result of \fBTk_MeasureChars\fR.
	.AP Display *display in
	Display on which to draw.
	.AP Drawable drawable in
	Window or pixmap in which to draw.
	.AP GC gc in
	Graphics context for drawing characters. The font selected into this GC
	must be the same as the \fItkfont\fR.
	.AP int "x, y" in
	Coordinates at which to place the left edge of the baseline when displaying
	\fIstring\fR.
	.VS 8.1
	.AP int firstByte in
	The index of the first byte of the first character to underline in the
	\fIstring\fR. Underlining begins at the left edge of this character.
	.AP int lastByte in
	The index of the first byte of the last character up to which the
	underline will be drawn. The character specified by \fIlastByte\fR
	will not itself be underlined.
	.VE 8.1
	.BE

	.SH DESCRIPTION
	.PP
	These routines are for measuring and displaying simple single-font,
	single-line, strings. To measure and display single-font, multi-line,
	justified text, refer to the documentation for \fBTk_ComputeTextLayout\fR.
	There is no programming interface in the core of Tk that supports
	multi-font, multi-line text; support for that behavior must be built on
	top of simpler layers.
	.VS 8.1
	Note that the interfaces described here are
	byte-oriented not character-oriented, so index values coming from Tcl
	scripts need to be converted to byte offsets using the
	\fBTcl_UtfAtIndex\fR and related routines.
	.VE 8.1
	.PP
	A glyph is the displayable picture of a letter, number, or some other
	symbol. Not all character codes in a given font have a glyph.
	Characters such as tabs, newlines/returns, and control characters that
	have no glyph are measured and displayed by these procedures in a
	platform-dependent manner; under X, they are replaced with backslashed
	escape sequences, while under Windows and Macintosh hollow or solid boxes
	may be substituted. Refer to the documentation for
	\fBTk_ComputeTextLayout\fR for a programming interface that supports the
	platform-independent expansion of tab characters into columns and
	newlines/returns into multi-line text.
	.PP
	\fBTk_MeasureChars\fR is used both to compute the length of a given
	string and to compute how many characters from a string fit in a given
	amount of space. The return value is the number of bytes from
	\fIstring\fR that fit in the space specified by \fImaxPixels\fR subject to
	the conditions described by \fIflags\fR. If all characters fit, the return
	value will be \fInumBytes\fR. \fI*lengthPtr\fR is filled with the computed
	width, in pixels, of the portion of the string that was measured. For
	example, if the return value is 5, then \fI*lengthPtr\fR is filled with the
	distance between the left edge of \fIstring\fR[0] and the right edge of
	\fIstring\fR[4].
	.PP
	\fBTk_TextWidth\fR is a wrapper function that provides a simpler interface
	to the \fBTk_MeasureChars\fR function. The return value is how much
	space in pixels the given \fIstring\fR needs.
	.PP
	\fBTk_DrawChars\fR draws the \fIstring\fR at the given location in the
	given \fIdrawable\fR.
	.PP
	\fBTk_UnderlineChars\fR underlines the given range of characters in the
	given \fIstring\fR. It doesn't draw the characters (which are assumed to
	have been displayed previously by \fBTk_DrawChars\fR); it just draws the
	underline. This procedure is used to underline a few characters without
	having to construct an underlined font. To produce natively underlined
	text, the appropriate underlined font should be constructed and used.

	.SH KEYWORDS
	font