require 'fltk'

class Point < FLTK::Box
  def initialize(parent,x,y)
    super(x,y,10,10)
    @parent = parent
    @enter  = false
  end

  def draw
    super
    text = "(#{x},#{y})"
    if( @enter )
      @parent.color(FLTK::RED)
    else
      @parent.color(FLTK::BLACK)
    end
    @parent.text_draw(text, x, y)
  end

  def handle(e)
    case e
    when FLTK::ENTER
      @parent.mark_item(self)
      @enter = true
      @parent.redraw
      return true
    when FLTK::LEAVE
      @parent.mark_item(nil)
      @enter = false
      @parent.redraw
      return true
    else
      return false
    end
  end
end

class Line
  def initialize(parent, x1, y1, x2, y2)
    @parent = parent
    box1 = Point.new(parent,x1,y1)
    box2 = Point.new(parent,x2,y2)
    @corner = [box1,box2]
    add_corner((x1 + x2) / 2, (y1 + y2) / 2)
  end

  def add_corner(x, y)
    box = Point.new(@parent,x,y)
    @corner[1,0] = box
  end

  def draw
    for i in 0..(@corner.length - 2)
      box1 = @corner[i]
      box2 = @corner[i+1]
      box1.redraw
      box2.redraw
      @parent.line(box1.x, box1.y , box2.x, box2.y)
    end
  end
end

class MyCanvas < FLTK::Widget
  include FLTK::Drawable

  def initialize(label)
    super(400,400,label)
    @cur   = nil
    @lines = [
      Line.new(self, 100, 100, 200, 200),
      Line.new(self, 100, 200, 200, 300),
      Line.new(self, 200, 100, 300, 200),
    ]
  end

  def draw
    super()
    clear
    color(FLTK::BLACK)
    @lines.each{|line| line.draw}
  end

  def handle(e)
    case e
    when FLTK::PUSH
      return true
    when FLTK::DRAG
      if( @cur )
	@cur.position(FLTK.event_x, FLTK.event_y)
      end
      redraw
      return true
    else
      return false
    end
  end

  def mark_item(obj)
    print "mark_item(#{obj.inspect})\n"
    @cur = obj
  end
end

class MyWindow < FLTK::Window
  def initialize(label)
    super(400,400,label)
    @canvas = MyCanvas.new("#{label} Canvas")
  end
end

w = MyWindow.new("MyWindow")
w.show

FLTK.run