Dot drawer plugin on Jekyll and Octopress.

dot.rb

# Title: Dot drawer
# Author: Ryo HAYASHI <ryo88c@gmail.com>
#
# Syntax:
# {% dot %}
# dotCode
# {% enddot %}

require 'open3'
require './plugins/raw'
require 'fileutils'

module Jekyll
    class DotBlock < Liquid::Block
        def render(context)
            site = context.registers[:site]
            config = site.config['dot']
            dotCode = @nodelist.join

            if config['tmp_folder'].nil?
                tmpRoot = '_dot'
            else
                tmpRoot = File.expand_path(config['tmp_folder'])
            end
            imgFolderPath = tmpRoot + "/images/"
            if !File.exist?(imgFolderPath)
                FileUtils::mkdir_p imgFolderPath
                puts "Create Dot image folder: " + imgFolderPath + "\n"
            end

            if config['dot_bin'].nil?
                dotPath = 'dot'
            else
                dotPath = File.expand_path(config['dot_bin'])
            end
            if !File.exist?(dotPath)
                throw Exception("Can't find Dot binary: " + dotPath);
            end

            fileName = Digest::MD5.hexdigest(dotCode)
            imgFilePath = imgFolderPath + fileName + ".png"
            dotFilePath = tmpRoot + "/" + fileName + ".dot"
            if File.exist?(imgFilePath)
                puts "Dot image already exist: " + imgFilePath + "\n"
            else
                cmd = "touch " + dotFilePath + "; cat <<EOT > " + dotFilePath + "\n" + dotCode;
                result, status = Open3.capture2e(cmd)
                puts "Create " + dotFilePath + " is " + status.inspect() + " > " + result

                cmd = dotPath + " -Tpng " + dotFilePath + " -o " + imgFilePath
                result, status = Open3.capture2e(cmd)
                puts "Create " + imgFilePath + " is " + status.inspect() + " > " + result
            end

            site.static_files << Jekyll::StaticFile.new(site, tmpRoot, '/images/', fileName + ".png")
            source = "<img src='/images/" + fileName + ".png'>"
        end
    end
end

Liquid::Template.register_tag('dot', Jekyll::DotBlock)