gistfile1.rb

require 'sdl2'
require 'optparse'
require 'tmpdir'
 
class App
  include SDL2
  
  def initialize
    @width = @height = nil
    @fullscreen = false
  end
  
  def options
    opts = OptionParser.new("USAGE: ptool.rb [OPTIONS] PDFFILE")
    opts.on("-w WIDTH", Integer){|w| @width = w }
    opts.on("-h HEIGHT", Integer){|h| @height = h }
    opts.on("-f"){ @fullscreen = true }
    
    opts
  end

  def run(argv)
    SDL2.init(SDL2::INIT_EVERYTHING)

    options.parse!(argv)
    pdffile = argv.shift

    show_usage_and_exit if pdffile.nil?

    open_window
    
    Dir.mktmpdir do |dir|
      prepare_pdf(dir, pdffile)
      @ppmfiles = Dir.glob(File.join(dir, "/p*.ppm")).sort_by{|path|
        /p-(\d+)\.ppm\Z/.match(path)[1].to_i
      }
      @pages = @ppmfiles.map{|path| @renderer.load_texture(path) }
      @current = 0
      @extra = method(:do_nothing)
      @blend_modes = [BLENDMODE_NONE, BLENDMODE_BLEND, BLENDMODE_ADD, BLENDMODE_MOD]
      show_page
      @renderer.draw_blend_mode = new_blend_mode
      Mouse::Cursor.hide

      @add_blend_demo = AddBlendDemo.new(@window, @renderer)
      
      loop do
        while ev = Event.poll
          quit = handle_event(ev)
          return if quit
        end

        @extra.call
        sleep 0.01
        @renderer.present
      end
    end
  end

  def show_usage_and_exit
    print options.help
    exit
  end

  def open_window
    if @fullscreen
      mode = desktop_mode()
      @width ||= mode.w
      @height ||= mode.h
      x = y = 0
    else
      @width ||= 640
      @height ||= 480
      x = y = Window::POS_CENTERED
    end
    
    flags = 0
    flags |= Window::FULLSCREEN_DESKTOP if @fullscreen
    flags |= Window::OPENGL

    @window = Window.create("ptool", x, y, @width, @height, flags)
    @renderer = @window.create_renderer(-1, 0)
  end

  def desktop_mode
    window = Window.create("checker", 0, 0, 40, 40, 0)
    mode = window.display.desktop_mode
    window.destroy
    mode
  end
  
  def prepare_pdf(dir, pdffile)
    prefix = "p"
    system("pdftoppm", "-scale-to-x", @width.to_s, "-scale-to-y", @height.to_s,
           pdffile, File.join(dir, prefix))
  end

  def handle_event(ev)
    case ev
    when Event::Quit
      return true
    when Event::KeyDown
      case ev.sym
      when Key::ESCAPE
        return true
      when Key::LEFT
        @current -= 1
        @current = 0 if @current < 0
        show_page
      when Key::RIGHT
        @current += 1
        @current = @pages.size - 1 if @current >= @pages.size
        show_page
      when Key::R
        angle = 0.0
        @extra = proc{
          angle += 0.3
          @renderer.clear
          @renderer.copy_ex(@pages[@current], nil, nil, angle, nil, 0)
        }
      when Key::SPACE
        @extra = method(:do_nothing)
        show_page
      when Key::Z
        scale = 1.0
        ds = -0.01
        @extra = proc{
          scale += ds 
          ds *= -1 if flip_scale?(scale, ds)
          w = (@width*scale).ceil
          h = (@height*scale).ceil
          @renderer.clear
          @renderer.copy(@pages[@current], nil, Rect.new(0,0,w,h))
        }
      when Key::B
        @renderer.draw_blend_mode = new_blend_mode
      when Key::S
        @extra = method(:do_nothing)
      when Key::P
        @extra = proc {
          case rand(10)
          when 0
            x1 = rand(@width); y1 = rand(@height)
            x2 = rand(@width); y2 = rand(@height)
            set_random_color
            @renderer.draw_line(x1, x2, y1, y2)
          when 1
            set_random_color
            @renderer.draw_rect(random_rect)
          when 2
            set_random_color
            @renderer.fill_rect(random_rect)
          end
        }
      when Key::A
        @add_blend_demo.update
      end
    end

    return false
  end

  def show_page
    page = @pages[@current]
    @renderer.copy(page, nil, nil)
  end

  def do_nothing
  end

  def flip_scale?(scale, ds)
    (scale < 0.5 && ds < 0) || (scale > 1.0 && ds > 0)
  end

  def set_random_color
    @renderer.draw_color = [rand(255), rand(255), rand(255), 128+rand(128)]
  end

  def random_rect
    x = rand(@width)
    y = rand(@height)
    Rect.new(x, y, rand(@width - x), rand(@height - y))
  end

  def new_blend_mode
    new_mode = @blend_modes.shift
    @blend_modes.push(new_mode)

    new_mode
  end

  class AddBlendDemo
    def initialize(window, renderer)
      @window = window
      @renderer = window.renderer
      prepare_textures
      @events = [method(:show_wallpaper), method(:show_flicker), method(:show_blending)]
    end

    def prepare_textures
      @wallpaper = @renderer.load_texture("rftg-wallpaper.jpg")
      @flicker = @renderer.load_texture("flicker.png")
    end

    def update
      @events.first.call
      @events.push(@events.shift)
    end
    
    def show_wallpaper
      @renderer.copy(@wallpaper, nil, nil)
    end

    def show_flicker
      @flicker.blend_mode = SDL2::BLENDMODE_NONE
      @renderer.copy(@flicker, nil, nil)
    end

    def show_blending
      @renderer.copy(@wallpaper, nil, nil)
      @flicker.blend_mode = SDL2::BLENDMODE_ADD
      @renderer.copy(@flicker, nil, nil)
    end
  end
end

if __FILE__ == $0
  App.new.run(ARGV)
end