'\"
'\" Generated from file 'canvas_trlines\&.man' by tcllib/doctools with format 'nroff'
'\"
.TH "canvas::track::lines" 3tk 0\&.1 tklib "Variations on a canvas"
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.SH NAME
canvas::track::lines \- Manage a group of rubber band lines
.SH SYNOPSIS
package require \fBTcl  8\&.5\fR
.sp
package require \fBTk  8\&.5\fR
.sp
package require \fBcanvas::tag  ?0\&.1?\fR
.sp
\fB::canvas::track\fR \fBlines\fR \fIobjectName\fR \fIcanvas\fR
.sp
\fBobjectName\fR \fBdestroy\fR
.sp
\fBobjectName\fR \fBstart\fR \fIcurrent\fR \fIp\fR\&.\&.\&.
.sp
\fBobjectName\fR \fBmove\fR \fIcurrent\fR
.sp
\fBobjectName\fR \fBdone\fR
.sp
.BE
.SH DESCRIPTION
This package provides a utility class managing the drawing of set of semi-crosshair (rubberband) lines\&.
.SH "CLASS API"
.TP
\fB::canvas::track\fR \fBlines\fR \fIobjectName\fR \fIcanvas\fR
This, the class command, creates and configures a new instance of the
tracker, 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\&.
.PP
.SH "INSTANCE API"
Instances of this class provide the following API:
.TP
\fBobjectName\fR \fBdestroy\fR
This method destroys the instance and releases all its
internal resources\&.
.sp
This operation does destroy the items representing the
tracked lines\&. It does not destroy the attached canvas\&.
.sp
The result of the method is an empty string\&.
.TP
\fBobjectName\fR \fBstart\fR \fIcurrent\fR \fIp\fR\&.\&.\&.
This method starts the tracking of a set of lines, one line per
point \fIp\fR, which specifies the destination end-point of each
line\&. All lines will have \fIcurrent\fR as a common end-point\&.
.sp
Note that a previously tracked set of lines is removed\&.
.sp
The result of the method is an empty string\&.
.sp
Each point is specified through a 2-element list containing its
x- and y-coordinates, in this order\&.
.TP
\fBobjectName\fR \fBmove\fR \fIcurrent\fR
This method updates the shared end-point of all rubberbands and redraws
them\&.
.sp
The result of the method is an empty string\&.
.sp
The point is specified through a 2-element list containing its
x- and y-coordinates, in this order\&.
.TP
\fBobjectName\fR \fBdone\fR
This method ends the tracking of the current set of lines and removes
them from the canvas\&.
.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, crosshair, rubberband, tracking