work on ugoira converter

Gemfile

@@ -43,6 +43,7 @@ gem 'capistrano'
 gem 'capistrano-ext'
 gem 'radix62', '~> 1.0.1'
 gem 'streamio-ffmpeg'
+gem 'rubyzip'
 
 # needed for looser jpeg header compat
 gem 'ruby-imagespec', :require => "image_spec", :git => "https://github.com/r888888888/ruby-imagespec.git", :branch => "exif-fixes"

Gemfile.lock

@@ -160,6 +160,7 @@ GEM
     ref (1.0.5)
     rmagick (2.13.3)
     ruby-prof (0.14.2)
+    rubyzip (1.1.6)
     safe_yaml (1.0.2)
     sanitize (2.1.0)
       nokogiri (>= 1.4.4)
@@ -263,6 +264,7 @@ DEPENDENCIES
   rmagick
   ruby-imagespec!
   ruby-prof
+  rubyzip
   sanitize
   sass-rails (~> 4.0.0)
   shoulda

app/logical/pixiv_ugoira_converter.rb

@@ -0,0 +1,122 @@
+class PixivUgoiraConverter
+  attr_reader :agent, :url, :write_path
+
+  def initialize(agent, url, write_path)
+    @agent = agent
+    @url = url
+    @write_path = write_path
+  end
+
+  def process(format)
+    folder = unpack(fetch_zipped_body)
+
+    if format == :gif
+      write_gif(folder)
+    elsif format == :webm
+      write_webm(folder)
+    elsif format == :apng
+      write_apng(folder)
+    end
+  end
+
+  def write_gif(folder)
+    anim = Magick::ImageList.new
+    delay_sum = 0
+    folder.each_with_index do |file, i|
+      image_blob = file.get_input_stream.read
+      image = Magick::Image.from_blob(image_blob).first
+      image.ticks_per_second = 1000
+      delay = frame_data[i]["delay"]
+      rounded_delay = (delay_sum + delay).round(-1) - delay_sum.round(-1)
+      image.delay = rounded_delay
+      delay_sum += delay
+      anim << image
+    end
+    
+    anim = anim.optimize_layers(Magick::OptimizeTransLayer)
+    anim.write(write_path)
+  end
+
+  def write_webm(folder)
+    Dir.mktmpdir do |tmpdir|
+      FileUtils.mkdir_p("#{tmpdir}/images")
+      folder.each_with_index do |file, i|
+        path = File.join(tmpdir, file.name)
+        image_blob = file.get_input_stream.read
+        File.open(path, "wb") do |f|
+          f.write(image_blob)
+        end
+      end
+      
+      delay_sum = 0
+      timecodes_path = File.join(tmpdir, "timecodes.tc")
+      File.open(timecodes_path, "w+") do |f|
+        f.write("# timecode format v2\n")
+        frame_data.each do |img|
+          f.write("#{delay_sum}\n")
+          delay_sum += img["delay"]
+        end
+        f.write("#{delay_sum}\n")
+      end
+      
+      ext = folder.first.name.match(/\.(.+)$/)[1]
+      system("ffmpeg -i #{tmpdir}/images/%06d.#{ext} -codec:v libvpx -crf 4 -b:v 5000k -an #{tmpdir}/tmp.webm")
+      system("mkvmerge -o #{tmpdir}/output.webm --timecodes 0:#{tmpdir}/timecodes.tc #{tmpdir}/tmp.webm")
+      
+      FileUtils.rm_rf(tmpdir)
+    end      
+  end
+
+  def write_apng(folder)
+      FileUtils.mkdir_p("pixiv_anim_#{pixiv_id}")
+      folder.each_with_index do |file, i|
+        frame_path = File.join("pixiv_anim_#{pixiv_id}", "frame#{"%03d" % i}.png")
+      delay_path = File.join("pixiv_anim_#{pixiv_id}", "frame#{"%03d" % i}.txt")
+        image_blob = file.get_input_stream.read
+      delay = frame_data[i]["delay"]
+      image = Magick::Image.from_blob(image_blob).first
+      image.format="PNG"
+      image.write(frame_path)
+      File.open(delay_path, "wb") do |f|
+          f.write("delay=#{delay}/1000")
+        end
+      end
+      system("apngasm pixiv_anim_#{pixiv_id}.png pixiv_anim_#{pixiv_id}/frame*.png")
+      FileUtils.rm_rf("pixiv_anim_#{pixiv_id}")
+      
+      puts "Animation successfully created as pixiv_anim_#{pixiv_id}.png"
+  end
+
+  def unpack(zipped_body)
+    Zip::CentralDirectory.new.read_from_stream(StringIO.new(zipped_body))
+  end
+
+  def fetch_zipped_body
+    zip_uri, frame_data = fetch_frames
+
+    zip_body = Net::HTTP.start(zip_uri.host) do |http|
+      http.get(zip_uri.path, {"Referer" => "http://pixiv.net"}).body
+    end
+  end
+
+  def fetch_frames
+    agent.get(url) do |page|
+      # Get the zip url and frame delay by parsing javascript contained in a <script> tag on the page.
+      # Not an neat solution, but I haven't found any other location that has the frame delays listed.
+      scripts = page.search("body script").find_all do |node|
+        node.text =~ /_ugoira600x600\.zip/
+      end
+
+      if scripts.any?
+        javascript = scripts.first.text
+        json = javascript.match(/;pixiv\.context\.ugokuIllustData\s+=\s+(\{.+\});(?:$|pixiv\.context)/)[1]
+        data = JSON.parse(json)
+        zip_uri = URI(data["src"].sub("_ugoira600x600.zip", "_ugoira1920x1080.zip"))
+        frame_data = data["frames"]
+        return [zip_uri, frame_data]
+      else
+        raise "Can't find javascript with frame data"
+      end
+    end
+  end
+end