An ActiveStorage analyzer that pulls out GPS and other details

sasa_analyzer.rb

require 'exifr/jpeg'

# Add to your Gemfile: gem 'exifr', '~> 1.3', '>= 1.3.6'
# I created the file in /lib/active_storage/sasa_analyzer.rb
# You will also need to update your application.rb: config.autoload_paths << "#{Rails.root}/lib/active_storage"

# Draws on https://ledermann.dev/blog/2018/05/15/exif-analyzer-for-active-storage/

class SasaAnalyzer < ActiveStorage::Analyzer

  ROTATIONS = {
    3 => 180,
    6 =>  90,
    8 => -90,
  }

  def self.accept?(blob)
    true
  end

  def metadata

    meta = {}

    if blob.image? && blob.filename.extension_without_delimiter=~/jpe?g/i
      download_blob_to_tempfile do |file|
        meta.merge!(from_exif(file))
      end
    end

    meta

  end

  private

    def from_exif(image)
      meta = {}
      begin
        image = EXIFR::JPEG.new(image.path)
        meta[:model]             = image.model
        meta[:width]             = image.width
        meta[:height]            = image.height
        meta[:date_time]         = image.date_time
        meta[:orientation]       = image.orientation.to_sym
        meta[:rotation_dregrees] = ROTATIONS[image.orientation.to_i]
        if image.gps
          meta[:latitude]  = image.gps.latitude
          meta[:longitude] = image.gps.longitude
          meta[:altitude]  = image.gps.altitude   if image.gps.altitude
        end
      rescue EXIFR::MalformedImage, EXIFR::MalformedJPEG
      end
      meta
    end

end