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## -*- tcl -*-
# # ## ### ##### ######## ############# #####################
##
# Canvas Behavior Module. Managing semi-crosshair rubber bands when
# dragging. Tracers are lines from fixed points to current location
# Purely visual. Driven from the outside. No bindings of its own.
##
## TODO : Callback to customize the rubberband lines.
# # ## ### ##### ######## ############# #####################
## Requisites
package require Tcl 8.5
package require Tk
package require snit
namespace eval ::canvas::track {
namespace export lines
namespace ensemble create
}
# # ## ### ##### ######## ############# #####################
## API
snit::type ::canvas::track::lines {
# # ## ### ##### ######## ############# #####################
## Lifecycle management
constructor {c} {
set mycanvas $c
return
}
destructor {
$self done
}
# # ## ### ##### ######## ############# #####################
## API.
method start {center args} {
if {![llength $args]} return
$self done
# args = list of pairs, each pair contains the x- and
# y-coordinates of a fixed point.
# center is current location.
set mycoords $args
set myitems {}
foreach p $mycoords {
lappend myitems [$mycanvas create line \
{*}$p {*}$center \
-width 0 -fill black -dash .]
}
return
}
method move {center} {
if {![llength $myitems]} return
foreach p $mycoords item $myitems {
$mycanvas coords $item {*}$p {*}$center
}
return
}
method done {} {
if {![llength $myitems]} return
$mycanvas delete {*}$myitems
set myitems {}
set mycoords {}
return
}
# # ## ### ##### ######## ############# #####################
## STATE
variable mycanvas {} ; # The canvas we are working with/on.
variable mycoords {} ; # List of fixed points for the rubberbands.
variable myitems {} ; # Liust of the canvas items representing the rubberbands.
##
# # ## ### ##### ######## ############# #####################
}
# # ## ### ##### ######## ############# #####################
## Ready
package provide canvas::track::lines 0.1
return
# # ## ### ##### ######## ############# #####################
## Scrap yard.
|
