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

 '\"
 '\" Copyright (c) 1990 The Regents of the University of California.
 '\" Copyright (c) 1994-1996 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: GetGC.3,v 1.2 1998/09/14 18:22:49 stanton 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)
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 '\" .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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 '\"	the option's class in the option database.
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 '\" .UL arg1 arg2
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 '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
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 '\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
 .if t .wh -1.3i ^B
 .nr ^l \n(.l
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 .de AP
 .ie !"\\$4"" .TP \\$4
 .el \{\
 .   ie !"\\$2"" .TP \\n()Cu
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 .AS Tcl_Interp Tcl_CreateInterp in/out
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 .\}
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 ..
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 ..
 .TH Tk_GetGC 3 "" Tk "Tk Library Procedures"
 .BS
 .SH NAME
 Tk_GetGC, Tk_FreeGC \- maintain database of read-only graphics contexts
 .SH SYNOPSIS
 .nf
 \fB#include <tk.h>\fR
 .sp
 GC
 \fBTk_GetGC\fR(\fItkwin, valueMask, valuePtr\fR)
 .sp
 \fBTk_FreeGC(\fIdisplay, gc\fR)
 .SH ARGUMENTS
 .AS "unsigned long" valueMask
 .AP Tk_Window tkwin in
 Token for window in which the graphics context will be used.
 .AP "unsigned long" valueMask in
 Mask of bits (such as \fBGCForeground\fR or \fBGCStipple\fR)
 indicating which fields of \fI*valuePtr\fR are valid.
 .AP XGCValues *valuePtr in
 Pointer to structure describing the desired values for the
 graphics context.
 .AP Display *display in
 Display for which \fIgc\fR was allocated.
 .AP GC gc in
 X identifier for graphics context that is no longer needed.
 Must have been allocated by \fBTk_GetGC\fR.
 .BE

 .SH DESCRIPTION
 .PP
 \fBTk_GetGC\fR and \fBTk_FreeGC\fR manage a collection of graphics contexts
 being used by an application.  The procedures allow graphics contexts to be
 shared, thereby avoiding the server overhead that would be incurred
 if a separate GC were created for each use.  \fBTk_GetGC\fR takes arguments
 describing the desired graphics context and returns an X identifier
 for a GC that fits the description.  The graphics context that is returned
 will have default values in all of the fields not specified explicitly
 by \fIvalueMask\fR and \fIvaluePtr\fR.
 .PP
 \fBTk_GetGC\fR maintains a
 database of all the graphics contexts it has created.  Whenever possible,
 a call to \fBTk_GetGC\fR will
 return an existing graphics context rather than creating a new one.  This
 approach can substantially reduce server overhead, so \fBTk_GetGC\fR
 should generally be used in preference to the Xlib procedure
 \fBXCreateGC\fR, which creates a new graphics context on each call.
 .PP
 Since the return values of \fBTk_GetGC\fR
 are shared, callers should never modify the graphics contexts
 returned by \fBTk_GetGC\fR.
 If a graphics context must be modified dynamically, then it should be
 created by calling \fBXCreateGC\fR instead of \fBTk_GetGC\fR.
 .PP
 When a graphics context
 is no longer needed, \fBTk_FreeGC\fR should be called to release it.
 There should be exactly one call to \fBTk_FreeGC\fR for
 each call to \fBTk_GetGC\fR.
 When a graphics context is no longer in use anywhere (i.e. it has
 been freed as many times as it has been gotten) \fBTk_FreeGC\fR
 will release it to the X server and delete it from the database.

 .SH KEYWORDS
 graphics context
	'\"
	'\" Copyright (c) 1990 The Regents of the University of California.
	'\" Copyright (c) 1994-1996 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: GetGC.3,v 1.2 1998/09/14 18:22:49 stanton 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
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	.if n .fi
	..
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	.\" 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'
	.\}
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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'
	.\}
	.\}
	.fi
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	..
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	'\" # box/sidebar if in box/sidebar mode, then invoked standard
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	'ti 0
	'nf
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	.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
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	..
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	.de DS
	.RS
	.nf
	.sp
	..
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	.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
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	.nf
	.ta .25i .5i .75i 1i
	..
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	.de CE
	.fi
	.RE
	..
	.de UL
	\\$1\l'\|0\(ul'\\$2
	..
	.TH Tk_GetGC 3 "" Tk "Tk Library Procedures"
	.BS
	.SH NAME
	Tk_GetGC, Tk_FreeGC \- maintain database of read-only graphics contexts
	.SH SYNOPSIS
	.nf
	\fB#include <tk.h>\fR
	.sp
	GC
	\fBTk_GetGC\fR(\fItkwin, valueMask, valuePtr\fR)
	.sp
	\fBTk_FreeGC(\fIdisplay, gc\fR)
	.SH ARGUMENTS
	.AS "unsigned long" valueMask
	.AP Tk_Window tkwin in
	Token for window in which the graphics context will be used.
	.AP "unsigned long" valueMask in
	Mask of bits (such as \fBGCForeground\fR or \fBGCStipple\fR)
	indicating which fields of \fI*valuePtr\fR are valid.
	.AP XGCValues *valuePtr in
	Pointer to structure describing the desired values for the
	graphics context.
	.AP Display *display in
	Display for which \fIgc\fR was allocated.
	.AP GC gc in
	X identifier for graphics context that is no longer needed.
	Must have been allocated by \fBTk_GetGC\fR.
	.BE

	.SH DESCRIPTION
	.PP
	\fBTk_GetGC\fR and \fBTk_FreeGC\fR manage a collection of graphics contexts
	being used by an application. The procedures allow graphics contexts to be
	shared, thereby avoiding the server overhead that would be incurred
	if a separate GC were created for each use. \fBTk_GetGC\fR takes arguments
	describing the desired graphics context and returns an X identifier
	for a GC that fits the description. The graphics context that is returned
	will have default values in all of the fields not specified explicitly
	by \fIvalueMask\fR and \fIvaluePtr\fR.
	.PP
	\fBTk_GetGC\fR maintains a
	database of all the graphics contexts it has created. Whenever possible,
	a call to \fBTk_GetGC\fR will
	return an existing graphics context rather than creating a new one. This
	approach can substantially reduce server overhead, so \fBTk_GetGC\fR
	should generally be used in preference to the Xlib procedure
	\fBXCreateGC\fR, which creates a new graphics context on each call.
	.PP
	Since the return values of \fBTk_GetGC\fR
	are shared, callers should never modify the graphics contexts
	returned by \fBTk_GetGC\fR.
	If a graphics context must be modified dynamically, then it should be
	created by calling \fBXCreateGC\fR instead of \fBTk_GetGC\fR.
	.PP
	When a graphics context
	is no longer needed, \fBTk_FreeGC\fR should be called to release it.
	There should be exactly one call to \fBTk_FreeGC\fR for
	each call to \fBTk_GetGC\fR.
	When a graphics context is no longer in use anywhere (i.e. it has
	been freed as many times as it has been gotten) \fBTk_FreeGC\fR
	will release it to the X server and delete it from the database.

	.SH KEYWORDS
	graphics context