WJG (19/05/09) Gnocl support for the Gnome Canvas widget enables all sorts of interesting manipulation to canvas objects. However, as Gnocl widget commmands and options are generally fashioned after the Gtk/Gnome library properties and functions the way to do things might not be apparent at first glance. Take adding or even deleting points from a polyline item. Here's a simple code example to show how its done.
#---------------
# Author: William J Giddings
# Date: 07/05/09
#---------------
#!/bin/sh
# the next line restarts using tclsh \
exec tclsh "$0" "$@"
#---------------
package require Gnocl
package require GnoclCanvas
# assuming this is a line..
# can canvaswidget
# id item it
proc addPoint {canv id pos newPoints} {
set coords [$canv itemCget $id -coords]
puts "$id = $coords"
# errochecking on number of items added, must be a multiple of 2!
foreach item $newPoints {
set coords [linsert $coords $pos $item]
incr pos
}
$canv itemConfigure $id -coords $coords
$canv update
}
# assuming this is a line..
# can canvaswidget
# id item it
proc deletePoint {canv id pos newPoints} {
set coords [$canv itemCget $id -coords]
puts "$id = $coords"
# errochecking on number of items added, must be a multiple of 2!
foreach item $newPoints {
set coords [linsert $coords $pos $item]
incr pos
}
$canv itemConfigure $id -coords $coords
$canv update
}
set canv [gnocl::canvas -background white -antialiased 1]
set coords {10 100 30 60 50 20 110 20 150 60 190 100}
$canv create line -coords $coords -fill blue -tags line
set but [gnocl::button \
-text "Add Extra Points" \
-onClicked {
addPoint $canv line 4 {103 103 125 152 151 17 5 5}
}]
set box [gnocl::box -orientation vertical]
$box add $canv -fill {1 1} -expand 1
$box add $but -fill {0 0} -expand 0
$canv itemConfigure dots -fill darkgreen
gnocl::window -title "Canvas" -child $box -onDestroy exit -widthRequest 320 -heightRequest 240| enter categories here |
|---|