# change the line below ("image" or "stack")
$meth = "image"

class Drawer
  def self.drawit_in_stack(w, h)
    $app.stroke gray(0.2)
    1000.times do |i|
      $app.fill gray(rand*0.6)
      $app.rect rand(w), rand(h), 10, 10
      $app.inscription "foo", :top => rand(h), :left => rand(w)
    end
  end

  def self.drawit_in_image(w, h)
    $app.image :width => w, :height => h, :left => 0, :top => 0 do
      $app.stroke gray(0.2)
      2000.times do |i|
        $app.fill gray(rand*0.6)
        $app.rect rand(w), rand(h), 10, 10

        ### WHAT I'd like to do (as in NodeBox):
        # $app.textsize 14
        # $app.text "foo", :top => rand(h), :left => rand(w)
        ###
      end
    end
  end
end

Shoes.app :width => 1000, :height => 500, :resizable => false do
  $app = self
  @view_w = width
  @view_h = height
  @canvas_w = 10000
  @canvas_h = 700
  @thumb_h  = 30
  @thumb_w  = (@thumb_h * @canvas_w)/@canvas_h
  @thumbview_w = (@view_w*@thumb_w)/@canvas_w
  @thumbview_h = (@view_h*@thumb_h)/@canvas_h
  @last_click = nil
  @scrollcanvas, @scrollview = [], []

  # compute the transparency
  def fader(tstart, steps, i)
    return tstart*(1.0-1.0/(steps-1)*i)
  end

  @view = stack :width => @view_w, :height => @view_h do
    background gray(0.8)
    @main = stack :width => @canvas_w, :height => @canvas_h do
      eval "Drawer::drawit_in_#{$meth}(@canvas_w, @canvas_h)"
    end

    # create thumbnail view: we use 30 different containers w/ varying
    # transparency, cycling through them to fade out
    30.times do |i|
      @scrollcanvas[i] = stack :width => @thumb_w+1, :height => @thumb_h+1,
          :top => height-@thumb_h-20, :left => width-@thumb_w-20 do
        fill   gray(0.9, fader(0.7, 30, i))
        stroke gray(0.5, fader(1.0, 30, i))
        rect 0, 0, @thumb_w, @thumb_h

        @scrollview[i] = image :width => @thumbview_w+1, :height => @thumbview_h+1 do
          fill   gray(0.7, fader(0.9, 30, i))
          stroke gray(0.4, fader(1.0, 30, i))
          rect 0, 0, @thumbview_w, @thumbview_h, 2
        end
      end
      @scrollcanvas[i].hide
    end
  end

  def constrain(prop, min, max)
    return (prop > max ? max : (prop < min ? min : prop))
  end

  def stop_scrollanim
    @scrollcanvas.each do |sc| sc.hide; end
    @scrollanim.stop
    @scrollanim = nil
  end

  def scroll_by(delx, dely)
    # move main canvas image
    left = @main.left()+delx
    top  = @main.top()+dely
    left = constrain(left, @view.width() - @main.width(), 0)
    top  = constrain(top,  @view.height() - @main.height(), 0)
    @main.move(left, top)

    # scale for thumbnail view, do fade animation
    svl = (-left*@thumb_w)/@canvas_w
    svr = (-top*@thumb_h)/@canvas_h
    stop_scrollanim if @scrollanim
    @scrollcanvas[0].show
    @scrollview[0].displace(svl, svr)
    @scrollanim = animate 30 do |i|
      if i >= 15 then
        i = i-15
        @scrollcanvas[i-1].hide if i > 0
        @scrollcanvas[i].show
        @scrollview[i].displace(svl, svr)
        stop_scrollanim if i == 29
      end
    end
  end

  click do |b,l,t|
    @last_click = [l,t]
  end

  release do |b,l,t|
    @last_click = nil
  end

  motion do |l,t|
    if @last_click then
      del = [l-@last_click[0], t-@last_click[1]]
      scroll_by(del[0], del[1])
      @last_click = [l,t]
    end
  end

  keypress do |k|
    del = 5
    ctrl_del = 50
    case k
    when :left:  scroll_by(del, 0);
    when :right: scroll_by(-del, 0);
    when :up:    scroll_by(0, del);
    when :down:  scroll_by(0, -del);
    when :control_left:  scroll_by(ctrl_del, 0);
    when :control_right: scroll_by(-ctrl_del, 0);
    when :control_up:    scroll_by(0, ctrl_del);
    when :control_down:  scroll_by(0, -ctrl_del);
    end
  end

end