#!/usr/local/bin/ruby -w

# From Thomas & Hunt : Programming Ruby (p. 159)

require 'tk'

class Draw
	def do_press(x, y)
		@start_x = x
		@start_y = y
		@current_line = TkcLine.new(@canvas, x, y, x, y)
	end
	def do_motion(x, y)
		if @current_line
			@current_line.coords @start_x, @start_y, x, y
		end
	end
	def do_release(x, y)
		if @current_line
			@current_line.coords @start_x, @start_y, x, y
			@current_line.fill 'black'
			@current_line = nil
		end
	end
	def initialize(parent)
		@canvas = TkCanvas.new(parent)
		@canvas.pack
		@start_x = @start_y = 0
		@canvas.bind("1", proc{|e| do_press(e.x, e.y)})
		@canvas.bind("2", proc{ puts @canvas.postscript({}) })
		@canvas.bind("B1-Motion", proc{|x, y| do_motion(x, y)}, "%x %y")
		@canvas.bind("ButtonRelease-1",
				proc{|x, y| do_release(x, y)}, "%x %y")
	end
end

root = TkRoot.new{ title 'Canvas' }
Draw.new(root)
Tk.mainloop