1 files changed, 36 insertions, 0 deletions
diff --git a/_plugins/graphviz-block.rb b/_plugins/graphviz-block.rb
new file mode 100644
index 0000000..4ddd2ee
--- /dev/null
+++ b/_plugins/graphviz-block.rb
@@ -0,0 +1,36 @@
+require 'tempfile'
+require 'digest'
+
+OUTPUT_DIR = '/images/graphviz'
+
+module Jekyll
+  class GraphvizBlock < Liquid::Block
+    def initialize(tag_name, options, tokens)
+      super
+      opts_list = options.split('|').map { |s| s.strip }
+      @name = opts_list[0]
+      @alt = opts_list[1]
+    end
+
+    def render(context)
+      source = super
+      site = context.registers[:site]
+      FileUtils.mkdir_p(File.join(site.source, OUTPUT_DIR))
+
+      filename = "#{@name}-#{Digest::SHA256.hexdigest(source + @alt)}.svg"
+      site_path = File.join(OUTPUT_DIR, filename)
+      os_path = File.join(site.source, site_path)
+
+      f = Tempfile.new('graphviz-input')
+      f.write(source)
+      f.close
+      `dot -Tsvg #{f.path} > #{os_path}`
+      f.unlink
+
+      site.static_files << Jekyll::StaticFile.new(site, site.source, OUTPUT_DIR, filename)
+      "<img src=\"#{site_path}\" alt=\"#{@alt}\" />"
+    end
+  end
+end
+
+Liquid::Template.register_tag('graphviz', Jekyll::GraphvizBlock)