canvas::track::lines(n)     Variations on a canvas     canvas::track::lines(n)



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NAME
       canvas::track::lines - Manage a group of rubber band lines

SYNOPSIS
       package require Tcl  8.5

       package require Tk  8.5

       package require canvas::tag  ?0.1?

       ::canvas::track lines objectName canvas

       objectName destroy

       objectName start current p...

       objectName move current

       objectName done

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DESCRIPTION
       This package provides a utility class managing the drawing of set of
       semi-crosshair (rubberband) lines.

CLASS API
       ::canvas::track lines objectName canvas
              This, the class command, creates and configures a new instance
              of the tracker, named objectName. The instance will be connected
              to the specified canvas widget.

              The result of the command is the fully qualified name of the
              instance command.

INSTANCE API
       Instances of this class provide the following API:

       objectName destroy
              This method destroys the instance and releases all its internal
              resources.

              This operation does destroy the items representing the tracked
              lines. It does not destroy the attached canvas.

              The result of the method is an empty string.

       objectName start current p...
              This method starts the tracking of a set of lines, one line per
              point p, which specifies the destination end-point of each line.
              All lines will have current as a common end-point.

              Note that a previously tracked set of lines is removed.

              The result of the method is an empty string.

              Each point is specified through a 2-element list containing its
              x- and y-coordinates, in this order.

       objectName move current
              This method updates the shared end-point of all rubberbands and
              redraws them.

              The result of the method is an empty string.

              The point is specified through a 2-element list containing its
              x- and y-coordinates, in this order.

       objectName done
              This method ends the tracking of the current set of lines and
              removes them from the canvas.

BUGS, IDEAS, FEEDBACK
       This document, and the package it describes, will undoubtedly contain
       bugs and other problems.  Please report such in the category canvas of
       the Tklib Trackers [http://core.tcl.tk/tklib/reportlist].  Please also
       report any ideas for enhancements you may have for either package
       and/or documentation.

KEYWORDS
       canvas, crosshair, rubberband, tracking



tklib                                 0.1              canvas::track::lines(n)
