Module: Tabula::LSD

Extended by:
FFI::Library
Defined in:
lib/tabula/line_segment_detector.rb

Constant Summary collapse

DETECT_LINES_DEFAULTS = 
{
  :scale_factor => nil,
  :image_size => 2048
}

Class Method Summary collapse

Class Method Details

.detect_lines(image, scale_factor = 1) ⇒ Object

image can be either a string (path to image) or a Java::JavaAwtImage::BufferedImage image to pixels: stackoverflow.com/questions/6524196/java-get-pixel-array-from-image



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# File 'lib/tabula/line_segment_detector.rb', line 67

def LSD.detect_lines(image, scale_factor=1)

  bimage = if image.class == Java::JavaAwtImage::BufferedImage
             image
           elsif image.class == String
             ImageIO.read(java.io.File.new(image))
           else
             raise ArgumentError, 'image must be a string or a BufferedImage'
           end

  image = LSD.image_to_image_float(bimage)

  lines_found_ptr = FFI::MemoryPointer.new(:int, 1)

  out = lsd(lines_found_ptr, image, bimage.getWidth, bimage.getHeight)

  lines_found = lines_found_ptr.get_int

  rv = []
  lines_found.times do |i|
    a = out[7*4*i].read_array_of_type(:float, 7)

    a_round = a[0..3].map(&:round)
    p1, p2 = [[a_round[0], a_round[1]], [a_round[2], a_round[3]]]

    rv << Tabula::Ruling.new(p1[1] * scale_factor,
                             p1[0] * scale_factor,
                             (p2[0] - p1[0]) * scale_factor,
                             (p2[1] - p1[1]) * scale_factor)
  end

  free_values(out)
  bimage.flush
  bimage.getGraphics.dispose
  image = nil

  return rv
end

.detect_lines_in_pdf(pdf_path, options = {}) ⇒ Object 



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# File 'lib/tabula/line_segment_detector.rb', line 40

def LSD.detect_lines_in_pdf(pdf_path, options={})
  options = DETECT_LINES_DEFAULTS.merge(options)

  pdf_file = PDDocument.loadNonSeq(java.io.File.new(pdf_path), nil)
  lines = pdf_file.getDocumentCatalog.getAllPages.to_a.map do |page|
    bi = Tabula::Render.pageToBufferedImage(page, options[:image_size])
    detect_lines(bi, options[:scale_factor] || (page.findCropBox.width / options[:image_size]))
  end
  pdf_file.close
  lines
end

.detect_lines_in_pdf_page(pdf_path, page_number, options = {}) ⇒ Object

zero-indexed page_number



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# File 'lib/tabula/line_segment_detector.rb', line 53

def LSD.detect_lines_in_pdf_page(pdf_path, page_number, options={})
  options = DETECT_LINES_DEFAULTS.merge(options)

  pdf_file = Extraction.openPDF(pdf_path)
  page = pdf_file.getDocumentCatalog.getAllPages[page_number]
  bi = Tabula::Render.pageToBufferedImage(page,
                                          options[:image_size])
  pdf_file.close
  detect_lines(bi,
               options[:scale_factor] || (page.findCropBox.width / options[:image_size]))
end