'\"
'\" Generated from file 'canvas_ecircle\&.man' by tcllib/doctools with format 'nroff'
'\"
.TH "canvas::edit::circle" 3tk 0\&.1 tklib "Variations on a canvas"
.\" The -*- nroff -*- 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 ?manpage?
.\"	Start of list of standard options for a Tk widget. The manpage
.\"	argument defines where to look up the standard options; if
.\"	omitted, defaults to "options". The options follow on successive
.\"	lines, in three 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.
.\"
.\" .QW arg1 ?arg2?
.\"	Print arg1 in quotes, then arg2 normally (for trailing punctuation).
.\"
.\" .PQ arg1 ?arg2?
.\"	Print an open parenthesis, arg1 in quotes, then arg2 normally
.\"	(for trailing punctuation) and then a closing parenthesis.
.\"
.\"	# 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
'ie '\\$1'' .ds So \\fBoptions\\fR
'el .ds So \\fB\\$1\\fR
.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 \\*(So 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
..
.\"	# UL - underline word
.de UL
\\$1\l'|0\(ul'\\$2
..
.\"	# QW - apply quotation marks to word
.de QW
.ie '\\*(lq'"' ``\\$1''\\$2
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\$2
..
.\"	# PQ - apply parens and quotation marks to word
.de PQ
.ie '\\*(lq'"' (``\\$1''\\$2)\\$3
.\"" fix emacs highlighting
.el (\\*(lq\\$1\\*(rq\\$2)\\$3
..
.\"	# QR - quoted range
.de QR
.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
..
.\"	# MT - "empty" string
.de MT
.QW ""
..
.BS
.SH NAME
canvas::edit::circle \- Editing a circle on a canvas
.SH SYNOPSIS
package require \fBTcl  8\&.5\fR
.sp
package require \fBTk  8\&.5\fR
.sp
package require \fBcanvas::edit::points  ?0\&.1?\fR
.sp
package require \fBcanvas::edit::circle  ?0\&.1?\fR
.sp
\fB::canvas::edit\fR \fBcircle\fR \fIobjectName\fR \fIcanvas\fR \fIoptions\fR\&.\&.\&.
.sp
\fBobjectName\fR \fBdestroy\fR
.sp
\fBobjectName\fR \fBenable\fR
.sp
\fBobjectName\fR \fBdisable\fR
.sp
\fBobjectName\fR \fBactive\fR
.sp
\fBobjectName\fR \fBset\fR \fIminx\fR \fIminy\fR \fImaxx\fR \fImaxy\fR
.sp
\fBobjectName\fR \fBclear\fR
.sp
\fBactiveCmd\fR \fIeditorObj\fR \fIid\fR
.sp
\fBcreateCmd\fR \fIcanvas\fR \fIx\fR \fIy\fR
.sp
\fBdataCmd\fR \fIeditorObj\fR \fIcoordinates\fR
.sp
.BE
.SH DESCRIPTION
This package provides a class whose instances handle editing a circle on a canvas\&. Instances can be
configured with regard to the visual appearance of the markers denoting the circle's principal
points\&. Note that instances do not store the edited circle themselves, but delegate this to a
configurable object\&.
.SH INTERACTION
.PP
The circle editor internally uses an instance of package \fBcanvas::edit::points\fR,
and inherits all the options and behaviours for it\&. The color options are additionally applied to
the circle element of this editor
.PP
Beyond that it provides an option, \fB-circle-config\fR, to customize the circle item used
to render the circle through its principal points\&. Note that it cannot overide the inherited color
options\&.
.PP
During interaction instances execute a state machine where the user creates two points, at
which point the system completes the circle and reports it\&. At that point the system prevents adding
more points\&. Dragging the points is still possible, enabling resizing and moving the
circle\&. Deleting any of the principal points deletes the entire circle, at which point the system is
again ready for the creation of a new circle from two points\&.
.SH "CLASS API"
.TP
\fB::canvas::edit\fR \fBcircle\fR \fIobjectName\fR \fIcanvas\fR \fIoptions\fR\&.\&.\&.
This, the class command, creates and configures a new instance of a
circle editor, named \fIobjectName\fR\&. The instance will be
connected to the specified \fIcanvas\fR widget\&.
.sp
The result of the command is the fully qualified name of the
instance command\&.
.sp
The options accepted here, and their values, are explained in
the section \fBOptions\fR\&.
.PP
.SH "INSTANCE API"
Instances of the circle editors provide the following API:
.TP
\fBobjectName\fR \fBdestroy\fR
This method destroys the circle editor and releases all its
internal resources\&.
.sp
Note that this operation does not destroy the items the editor
managed on the attached canvas, nor the canvas itself\&.
.sp
The result of the method is an empty string\&.
.TP
\fBobjectName\fR \fBenable\fR
This method activates editing of the circle on the canvas\&. This
is the default after instance creation\&. A call is ignored if the
editor is already active\&.
.sp
The result of the method is an empty string\&.
.sp
The complementary method is \fBdisable\fR\&. The interogatory
method for the current state is \fBactive\fR\&.
.TP
\fBobjectName\fR \fBdisable\fR
This method disables editing of the circle on the canvas\&. A call
is ignored if the editor is already disabled\&.
.sp
The result of the method is an empty string\&.
.sp
The complementary method is \fBenable\fR\&. The interogatory
method for the current state is \fBactive\fR\&.
.TP
\fBobjectName\fR \fBactive\fR
This method queries the editor state\&.
.sp
The result of the method is a boolean value, \fBtrue\fR if
the editor is active, and \fBfalse\fR otherwise, i\&.e\&. disabled\&.
.sp
The methods to change the state are \fBenable\fR and
\fBdisable\fR\&.
.TP
\fBobjectName\fR \fBset\fR \fIminx\fR \fIminy\fR \fImaxx\fR \fImaxy\fR
This method programmatically set the circle from the border coordinates\&.
This writes over a previous (possibly partial) circle\&.
.sp
The result of the method is an empty string\&.
.sp
Note that this method goes through the whole set of callbacks invoked when the principal
points are created, i\&.e\&. \fB-create-cmd\fR, and, more importantly, \fB-data-cmd\fR\&.
.sp
This is the method through which to load a pre-existing circle into an editor instance\&.
.TP
\fBobjectName\fR \fBclear\fR
This method programmatically removes the circle from the editor, making the way free for creating
a new one\&.
.sp
The result of the method is an empty string\&.
.sp
Note that this method goes through the same callbacks invoked when the user interactively
removes a principal point, i\&.e\&. \fB-data-cmd\fR\&.
.PP
.SH OPTIONS
The class command accepts the following options
.TP
\fB-active-cmd\fR \fIcommand-prefix\fR
The value of this option is a command prefix the editor will invoke when the mouse enters or leaves
the circle or one of the principal points managed by the instance\&.
.sp
If not specified it defaults to an empty command which does nothing\&.
.sp
The signature of this command prefix is
.RS
.TP
\fBactiveCmd\fR \fIeditorObj\fR \fIid\fR
.sp
The \fIid\fR identifies the entered object\&.
.sp
An empty \fIid\fR indicates that the last entered object was left\&.
.sp
The value \fBcircle\fR indicates that the circle's outline was entered\&.
.sp
Any other value is a code for one of the circle's principal points, i\&.e\&. \fBcenter\fR, and
\fBedge\fR\&.
.sp
The result of this method is ignored\&.
.RE
.TP
\fB-add-remove-point\fR \fIeventspec\fR
The value of this option is an event specification (without bracketing angles) declaring which event
will trigger adding and removing a point\&.
.sp
This option can only be set at construction time\&.
.sp
The default setup uses different events for adding and removing points, \fBButtonPress-1\fR
and \fBButtonPress-2\fR respectively\&.
.sp
When using this option the same event is used for both operations\&. This is no problem because
adding is bound as canvas-global event while removal is bound to the relevant canvas items\&.
.TP
\fB-circle-config\fR \fIlist\fR
The value of this option is a list of options and their values to be applied to the internal circle
item whenever it is regenerated after changes\&.
Note that these options \fIcannot\fR override the principal coloring of the circle as applied by
the main options \fB-color\fR and \fB-hilit-color\fR\&.
.sp
If not specified it defaults to the empty list\&.
.TP
\fB-color\fR \fIcolorspec\fR
The value of this option is the fill color for the default item created when adding a point, and no
\fB-create-cmd\fR is specified\&.
.sp
The default value is \fBSkyBlue2\fR\&.
.TP
\fB-create-cmd\fR \fIcommand-prefix\fR
The value of this option is a command prefix the editor will invoke when it has to create a new
principal point\&.
.sp
While this option can be set after construction, it is recommended to use this feature only
as a means of inserting custom processing to be done at creation time which remembers and calls the
previous value of the option\&.
.sp
If not specified it defaults to a command which will create a
black-bordered blue circle of radius 3 centered on the location of the
new point\&.
.sp
The signature of this command prefix is
.RS
.TP
\fBcreateCmd\fR \fIcanvas\fR \fIx\fR \fIy\fR
The result of the command prefix \fImust\fR be a list of the canvas items it created to represent
the marker\&. Note here that the visual representation of a "principal point" may consist of multiple
canvas items in an arbitrary shape\&.
.sp
The returned list of items is allowed to be empty, and such is taken as signal that the
callback vetoed the creation of the principal point\&.
.RE
.TP
\fB-data-cmd\fR \fIcommand-prefix\fR
The value of this option is a command prefix the editor will invoke when the circle was edited in
some way (created, modified, deleted)\&. This is how the editor delegates the actual storage of the
circle information to an outside object\&.
.sp
This option can only be set at construction time\&.
.sp
If not specified it defaults to an empty string and is ignored
by the editor, i\&.e\&. not invoked\&.
.sp
The signature of this command prefix is
.RS
.TP
\fBdataCmd\fR \fIeditorObj\fR \fIcoordinates\fR
This callback is invoked when the circle was changed either interactively, or programmatically\&.
See instance method \fBset\fR for the latter\&.
.sp
The \fIeditorObj\fR identifies the instance invoking the callback, whereas \fIcoordinates\fR
is a list of 4 elements, containing the min x, and y, and the max x and y coordinates of the
circle, in this order\&.
.sp
The result of this method is ignored\&.
.RE
.TP
\fB-drag-point\fR \fIeventspec\fR
The value of this option is an event specification (without bracketing angles) declaring which event
will trigger a drag action on points\&.
.sp
This option can only be set at construction time\&.
.sp
The default specification is \fBButtonPress-3\fR\&.
.TP
\fB-hilit-color\fR \fIcolorspec\fR
The value of this option is the highlight color for the default item created when adding a point,
and no \fB-highlight-cmd\fR is specified\&.
.sp
The default value is \fBred\fR\&.
.TP
\fB-kind\fR \fIname\fR
The value of this option is the canvas item type for the default item created when adding a point,
and no \fB-create-cmd\fR is specified\&.
Only item types specified through a bounding box are suitable\&.
.sp
The default value is \fBoval\fR\&.
.TP
\fB-radius\fR \fIint\fR
The value of this option is the radius for the default item created when adding a point,
and no \fB-create-cmd\fR is specified\&.
.sp
The default value is \fB3\fR\&.
.TP
\fB-tag\fR \fIstring\fR
The value of this option is the name of the canvas tag with which to
identify all items of all vertices managed by the editor\&.
.sp
This option can only be set at construction time\&.
.sp
If not specified it defaults to \fBCIRCLE\fR
.PP
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIcanvas\fR of the
\fITklib Trackers\fR [http://core\&.tcl\&.tk/tklib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.SH KEYWORDS
canvas, circle, editing