Class: Pdf::Utility::ImageCreator

Inherits:
Object
  • Object
show all
Defined in:
app/services/pdf/utility/image_creator.rb

Overview

Service object: image creator.

Instance Method Summary collapse

Instance Method Details

#call(pdf_path:, name:, base_name: nil) ⇒ Object 



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# File 'app/services/pdf/utility/image_creator.rb', line 5

def call(pdf_path:, name:, base_name: nil)
  image = nil
  base_name ||= name.downcase.parameterize.tr('_', '-')
  begin
    # Normalize PDFs accidentally saved with raw HTTP response headers.
    Pdf::Utility::FileNormalizer.call(pdf_path)

    # Rails blocks libvips' in-process PDF loader for untrusted uploads.
    # Rasterize page 1 in the bounded pdftoppm subprocess, which rejects
    # oversized output before returning, then lazily load its trusted PNG.
    rasterized_page = Pdf::Utility::CliRasterizer.render_page(pdf_path, page: 0, dpi: 400)
    cover = Vips::Image.new_from_file(rasterized_page.path, access: :sequential)
    # Write it to a jpg temp file
    file = Tempfile.new([base_name, '.jpeg'])
    file_path = file.path
    cover.write_to_file(file_path)
    file&.flush
    file&.fsync
    # Now we will open the file just to make sure
    vips_image = Vips::Image.new_from_file(file_path)
    # Test that the vips_image is sound
    if vips_image.width&.positive? && vips_image.height.positive?
      new_filename = "#{base_name}-#{SecureRandom.base58(6).downcase}"
      image = Image.create!(new_filename:,
                            title: "Cover for #{name}".first(134),
                            new_image: file_path,
                            skip_notify: true,
                            tags: ['pdf-thumbnail'])
    else
      logger.error "Could not generate thumbnail for #{name} from #{pdf_path}, file is empty"
    end
  rescue StandardError => e
    ErrorReporting.error(e, { pdf_path:, name:, base_name: })
  end
  image
ensure
  rasterized_page&.close
  rasterized_page&.unlink
  file&.close
  file&.unlink
end