Class: Banzai::Filter::KrokiFilter

Inherits:
HTML::Pipeline::Filter
  • Object
show all
Includes:
ActionView::Helpers::TagHelper
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 16

def call
  return doc unless settings.kroki_enabled

  diagram_selectors = ::Gitlab::Kroki.formats(settings)
                          .map do |diagram_type|
                            %(pre[data-canonical-lang="#{diagram_type}"] > code,
                            pre > code[data-canonical-lang="#{diagram_type}"])
                          end
                          .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['data-canonical-lang'] || node['data-canonical-lang']
    next unless diagram_selectors.include?(diagram_type)

    diagram_src = node.content
    image_src = create_image_src(diagram_type, diagram_format, diagram_src)
    img_tag = Nokogiri::HTML::DocumentFragment.parse(content_tag(:img, nil, src: image_src))
    img_tag = img_tag.children.first

    next if 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', diagram_type)
    img_tag.set_attribute('data-diagram-src', "data:text/plain;base64,#{Base64.strict_encode64(diagram_src)}")

    node.parent.replace(img_tag)
  end

  doc
end