Vips based image analyzer for Active Storage

fast_image.rb

# frozen_string_literal: true

module ActiveStorage
  class Analyzer::FastImage < ActiveStorage::Analyzer
    def self.accept?(blob)
      blob.image?
    end

    def metadata
      read_image do |image|
        if rotated_image?(image)
          { width: image.height, height: image.width }
        else
          { width: image.width, height: image.height }
        end
      end
    end

    private
      def read_image
        download_blob_to_tempfile do |file|
          require 'ruby-vips'
          image = Vips::Image.new_from_file(file.path, access: :sequential)

          if valid_image?(image)
            yield image
          else
            logger.info "Skipping image analysis because Vips doesn't support the file"
            {}
          end
        end
      rescue LoadError
        logger.info "Skipping image analysis because the ruby-vips gem isn't installed"
        {}
      rescue Vips::Error => error
        logger.error "Skipping image analysis due to an Vips error: #{error.message}"
        {}
      end

      def rotated_image?(image)
        orientation = image.get("exif-ifd0-Orientation")
        orientation.include?("Right-top") || orientation.include?("Left-bottom")
      end

      def valid_image?(image)
        image.avg
        true
      rescue ::Vips::Error
        false
      end
  end
end