require 'tk'

class TkMove
  def initialize( canvas, tag )
    canvas.itembind(tag,'1',proc{|x,y| self.plotDown canvas, x, y }, "%x %y")
    canvas.itembind(tag, 'B1-Motion',proc{|x,y| self.plotMove canvas, x, y }, "%x %y")
    @lastx, @lasty = 0, 0
  end
  def plotDown (w, x, y)
    w.dtag 'selected'
    w.addtag_withtag 'selected', 'current'
    w.raise 'current'
    @lastx, @lasty = x, y
  end

  def plotMove (w, x, y)
    w.move 'selected', x - @lastx, y - @lasty
    @lastx, @lasty = x, y
  end
end

c = TkCanvas.new.pack

m = TkMove.new(c, 'circle')
c.itembind('circle','Any-Enter',proc{c.itemconfigure 'current','fill','blue'})
c.itembind('circle','Any-Leave',proc{c.itemconfigure 'current','fill','red'})


TkcOval.new(c, 130, 70, 160, 100, 'fill'=>'red').addtag('circle')

Tk.mainloop