require 'tk'

x1 = TkVariable.new
y1 = TkVariable.new
x2 = TkVariable.new
y2 = TkVariable.new

TkFrame.new{|f|
  TkLabel.new(f,'text'=>'x1: ').pack('side'=>'left')
  TkEntry.new(f,'width'=>8, 'textvariable'=>x1 ).pack('side'=>'left')
  TkLabel.new(f,'text'=>'     y1: ').pack('side'=>'left')
  TkEntry.new(f,'width'=>8, 'textvariable'=>y1 ).pack('side'=>'left')
}.pack
TkFrame.new{|f|
  TkLabel.new(f,'text'=>'x2: ').pack('side'=>'left')
  TkEntry.new(f,'width'=>8, 'textvariable'=>x2 ).pack('side'=>'left')
  TkLabel.new(f,'text'=>'     y2: ').pack('side'=>'left')
  TkEntry.new(f,'width'=>8, 'textvariable'=>y2 ).pack('side'=>'left')
}.pack

c = TkCanvas.new(nil, 'background'=>'white' )

TkFrame.new{|f|
  TkButton.new(f,'text'=>'Plot', 'command'=>proc{ item = TkcOval.new(c, x1.to_i, y1.to_i, x1.to_i + 10, y1.to_i + 10, 'fill'=>'red'); item.addtag 'grph'  }).pack('side'=>'left')
  TkButton.new(f,'text'=>'Line', 'command'=>proc{ item = TkcLine.new(c, x1.to_i, y1.to_i, x2.to_i, y2.to_i, 'width'=>2 ); item.addtag 'grph' }).pack('side'=>'left')
  TkButton.new(f,'text'=>'Rectangle', 'command'=>proc{ item = TkcRectangle.new(c, x1.to_i, y1.to_i, x2.to_i, y2.to_i, 'width'=>2 ); item.addtag 'grph' }).pack('side'=>'left')
  TkButton.new(f,'text'=>'Oval', 'command'=>proc{ item = TkcOval.new(c, x1.to_i, y1.to_i, x2.to_i, y2.to_i, 'width'=>2 ); item.addtag 'grph' }).pack('side'=>'left')
  TkButton.new(f,'text'=>'EXIT', 'command'=>proc{exit}).pack('side'=>'left')
}.pack

c.pack

# c.itembind('grph','Any-Enter',proc{c.itemconfigure 'current','fill','blue'})
# c.itembind('grph','Any-Leave',proc{c.itemconfigure 'current','fill','red'})
c.itembind('grph','1',proc{|x,y| plotDown c, x, y }, "%x %y")
c.itembind('grph', 'B1-Motion',proc{|x,y| plotMove c, x, y }, "%x %y")

$plot = {'lastX'=>0, 'lastY'=>0 }

def plotDown (w, x, y)
  w.dtag 'selected'
  w.addtag_withtag 'selected', 'current'
  w.raise 'current'
  $plot['lastX'] = x
  $plot['lastY'] = y
end

def plotMove (w, x, y)
  w.move 'selected', x - $plot['lastX'], y - $plot['lastY']
  $plot['lastX'] = x
  $plot['lastY'] = y
end

Tk.mainloop