Class: CorpPdf::PDFWriter

Inherits:
Object
  • Object
show all
Defined in:
lib/corp_pdf/pdf_writer.rb

Overview

PDFWriter - Clean PDF writer for flattening documents Writes a complete PDF from parsed objects, consolidating incremental updates

Instance Method Summary collapse

Constructor Details

#initialize ⇒ PDFWriter

Returns a new instance of PDFWriter.



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# File 'lib/corp_pdf/pdf_writer.rb', line 7

def initialize
  # Work entirely in binary encoding to avoid UTF-8/ASCII-8BIT conflicts
  @buffer = "".b
  @offsets = [] # Track [obj_num, gen, offset] for xref table
  @xref_offset = 0
end

Instance Method Details

#output ⇒ Object 



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# File 'lib/corp_pdf/pdf_writer.rb', line 129

def output
  @buffer
end

#write_header ⇒ Object 



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# File 'lib/corp_pdf/pdf_writer.rb', line 14

def write_header
  @buffer << "%PDF-1.6\n".b
  # Binary marker (helps PDF readers identify binary content)
  @buffer << "%\xE2\xE3\xCF\xD3\n".b
end

#write_object(ref, body) ⇒ Object 



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# File 'lib/corp_pdf/pdf_writer.rb', line 20

def write_object(ref, body)
  obj_num, gen = ref
  offset = @buffer.bytesize
  @offsets << [obj_num, gen, offset]

  # Write object with proper PDF syntax
  # Use ASCII-8BIT encoding throughout to avoid conflicts
  @buffer << "#{obj_num} #{gen} obj\n".b

  # Body is already in binary from ObjectResolver
  @buffer << body.b

  # Ensure proper spacing before endobj
  @buffer << "\n".b unless body.end_with?("\n")
  @buffer << "endobj\n".b
end

#write_trailer(size, root_ref, info_ref = nil) ⇒ Object 



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# File 'lib/corp_pdf/pdf_writer.rb', line 114

def write_trailer(size, root_ref, info_ref = nil)
  trailer = "trailer\n".b
  trailer << "<<".b
  trailer << " /Size #{size}".b
  trailer << " /Root #{root_ref[0]} #{root_ref[1]} R".b
  trailer << " /Info #{info_ref[0]} #{info_ref[1]} R".b if info_ref
  trailer << " >>".b
  trailer << "\n".b
  trailer << "startxref\n".b
  trailer << "#{@xref_offset}\n".b
  trailer << "%%EOF\n".b

  @buffer << trailer
end

#write_xref ⇒ Object 



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# File 'lib/corp_pdf/pdf_writer.rb', line 37

def write_xref
  @xref_offset = @buffer.bytesize

  # Build xref table
  xref = "xref\n".b

  # Object 0 (free list head)
  xref << "0 1\n".b
  xref << "0000000000 65535 f \n".b

  # Sort offsets and group consecutive objects into subsections
  sorted = @offsets.sort_by { |num, gen, _offset| [num, gen] }

  # Find max object number to determine Size
  max_obj_num = sorted.map { |num, _gen, _offset| num }.max || 0

  # Build xref entries covering all objects from 0 to max_obj_num
  # Missing objects are marked as free (type 'f')
  i = 0
  current_obj = 0

  while current_obj <= max_obj_num
    # Find next existing object
    next_existing = sorted.find { |num, _gen, _offset| num >= current_obj }

    if next_existing && next_existing[0] == current_obj
      # Object exists - find consecutive run of existing objects
      first_num = current_obj
      run_length = 1

      while (i + run_length) < sorted.length &&
            sorted[i + run_length][0] == first_num + run_length &&
            sorted[i + run_length][1] == sorted[i][1]
        run_length += 1
      end

      # Write subsection header
      xref << "#{first_num} #{run_length}\n".b

      # Write entries in this subsection
      run_length.times do |j|
        offset = sorted[i + j][2]
        gen = sorted[i + j][1]
        xref << format("%010d %05d n \n", offset, gen).b
      end

      i += run_length
      current_obj = first_num + run_length
    else
      # Object doesn't exist - find consecutive run of missing objects
      first_missing = current_obj
      missing_count = 1

      while current_obj + missing_count <= max_obj_num
        check_obj = current_obj + missing_count
        if sorted.any? { |num, _gen, _offset| num == check_obj }
          break
        end

        missing_count += 1
      end

      # Write subsection header for missing objects
      xref << "#{first_missing} #{missing_count}\n".b

      # Write free entries
      missing_count.times do
        xref << "0000000000 65535 f \n".b
      end

      current_obj = first_missing + missing_count
    end
  end

  @buffer << xref
end