Image Viewer using Gosu and Ruby

gosu_image_viewer.rb

require "gosu"

module GosuImageViewer
  class Window < Gosu::Window
    def initialize(width=640, height=480)
      super(width, height, false)
      self.caption = "Image Viewer using Gosu"
      @images = []
      @scale = 1.0
      @angle = 0
      @mode = 1
      @spin = false
      @auto = false
      reset_auto_count
    end

    def add_image(path)
      @images << path.encode("UTF-8")
      load_image if @images.size == @mode
    end 

    def update
      @scale += 0.01 if button_down?(Gosu::KbL)
      @scale -= 0.01 if button_down?(Gosu::KbS)
      @angle += 1 if button_down?(Gosu::KbJ) || @spin
      @angle -= 1 if button_down?(Gosu::KbK)

      if @auto
        @auto_count -= 1
        if @auto_count <= 0
          @mode.times { next_image }
          reset_auto_count
        end
      end
    end

    def draw
      draw_image unless @images.empty?
    end

    def button_down(id)
      case id
      when Gosu::Kb0
        @mode = 0
      when Gosu::Kb1
        @mode = 1
      when Gosu::Kb2
        @mode = 2
        load_image
      when Gosu::Kb4
        @mode = 4
        load_image
      when Gosu::Kb9
        @mode = 9
        load_image
      when Gosu::KbN
        next_image
      when Gosu::KbP
        prev_image
      when Gosu::KbQ
        @spin = !@spin 
      when Gosu::KbA
        @auto = !@auto 
      when Gosu::KbR
        @scale = 1.0
        @angle = 0
      when Gosu::KbEscape
        close
      end
    end

    private
    def load_image
      @mode.times do |i|
        if @images[i].is_a?(String)
          path = @images[i]
          begin
            @images[i] = Gosu::Image.new(self, path, false)
          rescue RuntimeError => e
            p e
            @images.delete_at(i)
            load_image
          end
        end
      end
    end

    def next_image
      @images.push(@images.shift)
      load_image
    end

    def prev_image
      @images.unshift(@images.pop)
      load_image
    end

    def draw_image
      case @mode
      when 1
        draw_image_1(@images.first)
      when 2
        draw_image_2(@images.take(2))
      when 4
        draw_image_4(@images.take(4))
      when 9
        draw_image_9(@images.take(9))
      end
    end

    def draw_image_1(image)
      center_x = self.width * 0.5
      center_y = self.height * 0.5
      image.draw_rot(center_x, center_y, 1,
                     @angle, 0.5, 0.5,
                     image_factor_x(image), image_factor_y(image))
    end

    def draw_image_2(images)
      images.each_with_index do |image, i|
        center_x = self.width * (0.25 + i * 0.5)
        center_y = self.height * 0.5
        image.draw_rot(center_x, center_y, 1,
                       @angle, 0.5, 0.5,
                       image_factor_x(image, 0.5), image_factor_y(image))
      end
    end

    def draw_image_4(images)
      images.each_with_index do |image, i|
        center_x = self.width * (0.25 + i % 2 * 0.5)
        center_y = self.height * (0.25 + (i / 2).floor * 0.5)
        image.draw_rot(center_x, center_y, 1,
                       @angle, 0.5, 0.5,
                       image_factor_x(image, 0.5), image_factor_y(image, 0.5))
      end
    end

    def draw_image_9(images)
      images.each_with_index do |image, i|
        center_x = self.width * (0.166 + i % 3 * 0.333)
        center_y = self.height * (0.166 + (i / 3).floor * 0.333)
        image.draw_rot(center_x, center_y, 1,
                       @angle, 0.5, 0.5,
                       image_factor_x(image, 0.333), image_factor_y(image, 0.333))
      end
    end

    def image_factor_x(image, scale=1.0)
      if image.width > (self.width * scale)
        @scale * self.width * scale / image.width
      else
        @scale
      end
    end

    def image_factor_y(image, scale=1.0)
      if image.height > (self.height * scale)
        @scale * self.height * scale / image.height
      else
        @scale
      end
    end

    def reset_auto_count
      @auto_count = 60 * @mode
    end
  end
end

window = GosuImageViewer::Window.new
ARGV.each do |path|
  next if /\.(png|jpe?g|gif|bmp|raw|sgi|ico|psd|tiff?|tga|tpic)/i !~ path
  window.add_image(path)
end
window.show