Ruby qt binding sample app (graphics view/scene)

qt_app.rb

# Author: Nicolas Meylan
# Date: 22.10.14
# Encoding: UTF-8
# File: qt_app.rb
require 'Qt'


class QtApp < Qt::Widget
  # Constants
  MINERAL_COLORS = {A: '#006BFF', B: '#00ff45', V: '#e4e4e4', AGENT: '#A1499E'}
  # Avoid Memory leaks
  BLACK = Qt::Pen.new(Qt::Color.new('#000000'))
  GRAY = Qt::Pen.new(Qt::Color.new('#e4e4e4'))
  FIRST_LABEL_POINT = Qt::Point.new(0, 30)
  SECOND_LABEL_POINT = Qt::Point.new(0, 60)
  THIRD_LABEL_POINT = Qt::Point.new(0, 90)
  COLORS_BRUSHES = {A: Qt::Brush.new(Qt::Color.new(MINERAL_COLORS[:A])),
                    B: Qt::Brush.new(Qt::Color.new(MINERAL_COLORS[:B])),
                    AGENT: Qt::Brush.new(Qt::Color.new(MINERAL_COLORS[:AGENT])),
  }

  slots 'refresh_ui()'

  def initialize(environment)
    super()
    move 300, 300
    @graphic_scene = Qt::GraphicsScene.new(self)
    @graphic_view = Qt::GraphicsView.new(@graphic_scene,self)
    @graphic_view.resize(600, 600)
    @graphic_view.viewport_update_mode = 3
    setWindowTitle "Collective Sorting"


    @refresh_ui_timer = Qt::Timer.new(@graphic_scene)
    connect(@refresh_ui_timer, SIGNAL('timeout()'), self, SLOT('refresh_ui()'))
    @refresh_ui_timer.interval = 16
    @refresh_ui_timer.start

    @environment = environment
    @old_store = Hash.new { |h, k| h[k] = [] }
    @fps = 0
    update_block_size
    @start_time = @last_time = @current_time = Qt::Time.current_time
    show

  end

  def update_block_size
    @block_width = (self.size.width - 100) / @environment.cols
    @block_height = (self.size.height - 100) / @environment.rows
  end

  def set_environment(environment)
    @environment = environment
  end

  def draw_map
    @number_agents = 0
    @environment.rows.times.each do |row_index|
      @environment.cols.times.each do |col_index|
        cell_identifier = @environment.at(row_index, col_index)
        if should_draw?(cell_identifier)
          draw_rect(row_index, col_index, cell_identifier)
        end
      end
    end
  end

  def should_draw?(cell_identifier)
    !cell_identifier.eql?(:V)
  end

  def draw_rect(x, y, cell)
    if cell.is_a?(Agent)
      cell = agent_cell_identifier(cell)
      @number_agents += 1
    end
     @graphic_scene.addRect(100 + @block_width * x, @block_height * y, @block_width, @block_height, pen(cell), COLORS_BRUSHES[cell])
  end

  def agent_cell_identifier(cell)
    if cell.looted_identifier
      cell = cell.looted_identifier
    else
      cell = :AGENT
    end
    cell
  end

  def pen(cell)
    if cell.eql?(:AGENT)
      BLACK
    else
      GRAY
    end
  end

  def fps_counter
    @last_time = @current_time
    @current_time = Qt::Time.current_time
    @fps = 1000 / (@current_time.second * 1000 + @current_time.msec - (@current_time.second * 1000 + @last_time.msec))
  end

  def refresh_ui
    @graphic_scene.clear
    fps_counter
    draw_map
    @graphic_view.viewport.update
  end

  def closeEvent(event)
    @environment.interrupt
    # event.dispose
  end

end