Module: Mindee::PDF::PDFTools

Defined in:
lib/mindee/pdf/pdf_tools.rb

Overview

Monkey-patching for Origami

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.add_content_to_page(page, xobject_name, width, height) ⇒ Object 



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# File 'lib/mindee/pdf/pdf_tools.rb', line 104

def self.add_content_to_page(page, xobject_name, width, height)
  content = "q\n#{width} 0 0 #{height} 0 0 cm\n/#{xobject_name} Do\nQ\n"
  content_stream = Origami::Stream.new(content)
  page.Contents = content_stream
end

.create_xobject(image) ⇒ Object 



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# File 'lib/mindee/pdf/pdf_tools.rb', line 73

def self.create_xobject(image)
  image_io = Mindee::Image::ImageUtils.image_to_stringio(image)
  Origami::Graphics::ImageXObject.from_image_file(image_io, 'jpg')
end

.determine_colorspace(image) ⇒ Object 



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# File 'lib/mindee/pdf/pdf_tools.rb', line 95

def self.determine_colorspace(image)
  colorspace = image.data['colorspace']
  case colorspace
  when 'CMYK' then :DeviceCMYK
  when 'Gray', 'PseudoClass Gray' then :DeviceGray
  else :DeviceRGB
  end
end

.determine_filter(image) ⇒ Object 



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# File 'lib/mindee/pdf/pdf_tools.rb', line 86

def self.determine_filter(image)
  filter = image.data['properties']['filter']
  case filter
  when %r{Zip}i then :FlateDecode
  when %r{LZW}i then :LZWDecode
  else :DCTDecode
  end
end

.process_image_xobject(image_data, image_quality, width, height) ⇒ Object 



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# File 'lib/mindee/pdf/pdf_tools.rb', line 115

def self.process_image_xobject(image_data, image_quality, width, height)
  compressed_data = Image::ImageCompressor.compress_image(
    image_data,
    quality: image_quality,
    max_width: width,
    max_height: height
  )

  new_image = Origami::Graphics::ImageXObject.new
  new_image.data = compressed_data
  new_image.Width = width
  new_image.Height = height
  new_image.ColorSpace = :DeviceRGB
  new_image.BitsPerComponent = 8

  new_image
end

.set_page_dimensions(page, width, height) ⇒ Object 



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# File 'lib/mindee/pdf/pdf_tools.rb', line 110

def self.set_page_dimensions(page, width, height)
  page[:MediaBox] = [0, 0, width, height]
  page[:CropBox] = [0, 0, width, height]
end

.set_xobject_properties(xobject, image) ⇒ Object 



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# File 'lib/mindee/pdf/pdf_tools.rb', line 78

def self.set_xobject_properties(xobject, image)
  xobject.dictionary[:BitsPerComponent] = 8
  xobject.dictionary[:Filter] = determine_filter(image)
  xobject.dictionary[:Width] = image[:width]
  xobject.dictionary[:Height] = image[:height]
  xobject.dictionary[:ColorSpace] = determine_colorspace(image)
end

.source_text?(pdf_data) ⇒ Boolean

Checks whether the file has source_text. Sends false if the file isn't a PDF.

Parameters:

  • pdf_data (StringIO)

Returns:

  • (Boolean) —

    True if the pdf has source text, false otherwise.



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# File 'lib/mindee/pdf/pdf_tools.rb', line 48

def self.source_text?(pdf_data)
  begin
    pdf_data.rewind
    pdf = Origami::PDF.read(pdf_data)

    pdf.each_page do |page|
      next unless page[:Contents]

      contents = page[:Contents].solve
      contents = [contents] unless contents.is_a?(Origami::Array)

      contents.each do |stream_ref|
        stream = stream_ref.solve
        return true if stream_has_text?(stream)
      end
    end

    false
  end

  false
rescue Origami::InvalidPDFError
  false
end

.stream_has_text?(stream) ⇒ Boolean

Checks a PDFs stream content for text operators See https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008.pdf page 243-251.

Parameters:

  • stream (StringIO) —

    Stream object from a PDFs page.

Returns:

  • (Boolean) —

    True if a text operator is found in the stream.



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# File 'lib/mindee/pdf/pdf_tools.rb', line 37

def self.stream_has_text?(stream)
  data = stream.data
  return false if data.nil? || data.empty?

  text_operators = ['Tc', 'Tw', 'Th', 'TL', 'Tf', 'Tk', 'Tr', 'Tm', 'T*', 'Tj', 'TJ', "'", '"']
  text_operators.any? { |op| data.include?(op) }
end

Instance Method Details

#to_io_stream(params = {}) ⇒ StringIO

Returns:

  • (StringIO) 


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# File 'lib/mindee/pdf/pdf_tools.rb', line 8

def to_io_stream(params = {})
  options = {
    delinearize: true,
    recompile: true,
    decrypt: false,
  }
  options.update(params)

  if frozen? # incompatible flags with frozen doc (signed)
    options[:recompile] = nil
    options[:rebuild_xrefs] = nil
    options[:noindent] = nil
    options[:obfuscate] = false
  end
  load_all_objects unless @loaded

  intents_as_pdfa1 if options[:intent] =~ %r{pdf[/-]?A1?/i}
  delinearize! if options[:delinearize] && linearized?
  compile(options) if options[:recompile]

  io_stream = StringIO.new(output(options))
  io_stream.set_encoding Encoding::BINARY
  io_stream
end