Class: Banzai::Filter::KrokiFilter

Inherits:
HTML::Pipeline::Filter
  • Object
show all
Defined in:
lib/banzai/filter/kroki_filter.rb

Overview

HTML that replaces all diagrams supported by Kroki with the corresponding img tags. If the source content is large then the hidden attribute is added to the img tag.

Constant Summary collapse

MAX_CHARACTER_LIMIT = 
2000

Instance Method Summary collapse

Instance Method Details

#call ⇒ Object 


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# File 'lib/banzai/filter/kroki_filter.rb', line 13

def call
  return doc unless settings.kroki_enabled

  diagram_selectors = ::Gitlab::Kroki.formats(settings)
                          .map { |diagram_type| %(pre[lang="#{diagram_type}"] > code) }
                          .join(', ')

  xpath = Gitlab::Utils::Nokogiri.css_to_xpath(diagram_selectors)
  return doc unless doc.at_xpath(xpath)

  diagram_format = "svg"
  doc.xpath(xpath).each do |node|
    diagram_type = node.parent['lang']
    diagram_src = node.content
    image_src = create_image_src(diagram_type, diagram_format, diagram_src)
    img_tag = Nokogiri::HTML::DocumentFragment.parse(%(<img src="#{image_src}" />))
    img_tag = img_tag.children.first

    unless img_tag.nil?
      lazy_load = diagram_src.length > MAX_CHARACTER_LIMIT
      img_tag.set_attribute('hidden', '') if lazy_load
      img_tag.set_attribute('class', 'js-render-kroki')

      img_tag.set_attribute('data-diagram', node.parent['lang'])
      img_tag.set_attribute('data-diagram-src', "data:text/plain;base64,#{Base64.strict_encode64(node.content)}")

      node.parent.replace(img_tag)
    end
  end

  doc
end