images.rb

# frozen_string_literal: true

require 'jekyll'
# The fastimage gem may not be installed, and that is OK, we will fall back to another method
FASTIMAGE_AVAILABLE = true
begin
  require 'fastimage'
rescue LoadError
  Jekyll.logger.info '[GTN/Images] Could not load fastimage gem, disabling feature (probably due to conda)'
  FASTIMAGE_AVAILABLE = false
end

module Gtn
  # Module to handle pre-calculating image dimensions
  # We can then use those dimensions in the HTML to avoid reflow
  module Images
    def self.cache
      @@cache ||= Jekyll::Cache.new('ImageDimensions')
    end

    def self.html_image_dimensions(tuto_dir, url)
      return '' if !FASTIMAGE_AVAILABLE || (Jekyll.env == 'development')

      (width, height), path = get_image_dimensions(tuto_dir, url)
      return unless width && height

      [
        %(width="#{width}" height=#{height}),
        path
      ]
    end

    def self.get_image_dimensions(tuto_dir, url)
      if (match = url.match(%r{^{{\s*site.baseurl\s*}}/(.*)})) || (match = url.match(/{%\s*link\s*(.*)\s*%}/))
        _get_image_dimensions(match[1].strip)
      elsif !url.match(%r{https?://})
        img_path = File.absolute_path(File.join(tuto_dir, url))
        _get_image_dimensions(img_path) if File.exist?(img_path)
      else
        _get_image_dimensions(img_path)
      end
    end

    def self._get_image_dimensions(path)
      cache.getset(path) do
        [FastImage.size(path), path]
      rescue StandardError
        Jekyll.logger.info "[GTN/Images] Could not resolve size of #{path}"
      end
    end
  end
end