class PDF::Reader::PageLayout

page to be rendered as described by the page’s MediaBox attribute
media box should be a 4 number array that describes the dimensions of the
string that best approximates the way they’d appear on a render PDF page.
Takes a collection of TextRun objects and renders them into a single

def col_count 

def col_count
  @col_count ||= ((page_width  / @median_glyph_width) * 1.05).floor
end

def col_multiplier 

def col_multiplier
  @col_multiplier ||= page_width.to_f / col_count.to_f
end

def initialize(runs, mediabox) 

def initialize(runs, mediabox)
  # mediabox is a 4-element array for now, but it'd be nice to switch to a
  # PDF::Reader::Rectangle at some point
  PDF::Reader::Error.validate_not_nil(mediabox, "mediabox")
  @mediabox = process_mediabox(mediabox)
  @runs = runs
  @mean_font_size   = mean(@runs.map(&:font_size)) || DEFAULT_FONT_SIZE
  @mean_font_size = DEFAULT_FONT_SIZE if @mean_font_size == 0
  @median_glyph_width = median(@runs.map(&:mean_character_width)) || 0
  @x_offset = @runs.map(&:x).sort.first || 0
  lowest_y = @runs.map(&:y).sort.first || 0
  @y_offset = lowest_y > 0 ? 0 : lowest_y
end

def interesting_rows(rows)


=> [ "one", "two" ]
interesting_rows([ "", "one", "two", "" ])

beginning and end removed.
given an array of strings, return a new array with empty rows from the 
def interesting_rows(rows)
  line_lengths = rows.map { |l| l.strip.length }
  return [] if line_lengths.all?(&:zero?)
  first_line_with_text = line_lengths.index { |l| l > 0 }
  last_line_with_text  = line_lengths.size - line_lengths.reverse.index { |l| l > 0 }
  interesting_line_count = last_line_with_text - first_line_with_text
  rows[first_line_with_text, interesting_line_count].map
end

def local_string_insert(haystack, needle, index) 

def local_string_insert(haystack, needle, index)
  haystack[Range.new(index, index + needle.length - 1)] = String.new(needle)
end

def mean(collection) 

def mean(collection)
  if collection.size == 0
    0
  else
    collection.inject(0) { |accum, v| accum + v} / collection.size.to_f
  end
end

def median(collection) 

def median(collection)
  if collection.size == 0
    0
  else
    collection.sort[(collection.size * 0.5).floor]
  end
end

def page_height 

def page_height
  @mediabox.height
end

def page_width 

def page_width
  @mediabox.width
end

def process_mediabox(mediabox) 

def process_mediabox(mediabox)
  if mediabox.is_a?(Array)
    msg = "Passing the mediabox to PageLayout as an Array is deprecated," +
      " please use a Rectangle instead"
    $stderr.puts msg
    PDF::Reader::Rectangle.from_array(mediabox)
  else
    mediabox
  end
end

def row_count 

def row_count
  @row_count ||= (page_height / @mean_font_size).floor
end

def row_multiplier 

def row_multiplier
  @row_multiplier ||= page_height.to_f / row_count.to_f
end

def to_s 

def to_s
  return "" if @runs.empty?
  return "" if row_count == 0
  page = row_count.times.map { |i| " " * col_count }
  @runs.each do |run|
    x_pos = ((run.x - @x_offset) / col_multiplier).round
    y_pos = row_count - ((run.y - @y_offset) / row_multiplier).round
    if y_pos <= row_count && y_pos >= 0 && x_pos <= col_count && x_pos >= 0
      local_string_insert(page[y_pos-1], run.text, x_pos)
    end
  end
  interesting_rows(page).map(&:rstrip).join("\n")
end