DOKK / manpages / debian 12 / tklib / canvas::track::lines.3tk.en
canvas::track::lines(3tk) Variations on a canvas canvas::track::lines(3tk) 







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








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












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









  
::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.

  










Instances of this class provide the following API:



  

  
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.

  

  

  
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.

  

  

  
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.

  

  

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










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.








canvas, crosshair, rubberband, tracking







  

    0.1
    tklib