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{ TkcOval.new(c, x1.to_i, y1.to_i, x1.to_i + 4, y1.to_i + 4, 'fill'=>'red')  }).pack('side'=>'left')
  TkButton.new(f,'text'=>'Line', 'command'=>proc{ TkcLine.new(c, x1.to_i, y1.to_i, x2.to_i, y2.to_i, 'width'=>2 ) }).pack('side'=>'left')
  TkButton.new(f,'text'=>'Rectangle', 'command'=>proc{ TkcRectangle.new(c, x1.to_i, y1.to_i, x2.to_i, y2.to_i, 'width'=>2 ) }).pack('side'=>'left')
  TkButton.new(f,'text'=>'Oval', 'command'=>proc{ TkcOval.new(c, x1.to_i, y1.to_i, x2.to_i, y2.to_i, 'width'=>2 ) }).pack('side'=>'left')
  TkButton.new(f,'text'=>'EXIT', 'command'=>proc{exit}).pack('side'=>'left')
}.pack

c.pack

Tk.mainloop