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# coding: utf-8
# frozen_string_literal: true
require 'pdf/reader/overlapping_runs_filter'
class PDF::Reader
# Takes a collection of TextRun objects and renders them into a single
# string that best approximates the way they'd appear on a render PDF page.
#
# media box should be a 4 number array that describes the dimensions of the
# page to be rendered as described by the page's MediaBox attribute
class PageLayout
DEFAULT_FONT_SIZE = 12
def initialize(runs, mediabox)
raise ArgumentError, "a mediabox must be provided" if mediabox.nil?
@runs = merge_runs(OverlappingRunsFilter.exclude_redundant_runs(runs))
@mean_font_size = mean(@runs.map(&:font_size)) || DEFAULT_FONT_SIZE
@mean_font_size = DEFAULT_FONT_SIZE if @mean_font_size == 0
@mean_glyph_width = mean(@runs.map(&:mean_character_width)) || 0
@page_width = (mediabox[2] - mediabox[0]).abs
@page_height = (mediabox[3] - mediabox[1]).abs
@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 to_s
return "" if @runs.empty?
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
private
# given an array of strings, return a new array with empty rows from the
# beginning and end removed.
#
# interesting_rows([ "", "one", "two", "" ])
# => [ "one", "two" ]
#
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 row_count
@row_count ||= (@page_height / @mean_font_size).floor
end
def col_count
@col_count ||= ((@page_width / @mean_glyph_width) * 1.05).floor
end
def row_multiplier
@row_multiplier ||= @page_height.to_f / row_count.to_f
end
def col_multiplier
@col_multiplier ||= @page_width.to_f / col_count.to_f
end
def mean(collection)
if collection.size == 0
0
else
collection.inject(0) { |accum, v| accum + v} / collection.size.to_f
end
end
def each_line(&block)
@runs.sort.group_by { |run|
run.y.to_i
}.map { |y, collection|
yield y, collection
}
end
# take a collection of TextRun objects and merge any that are in close
# proximity
def merge_runs(runs)
runs.group_by { |char|
char.y.to_i
}.map { |y, chars|
group_chars_into_runs(chars.sort)
}.flatten.sort
end
def group_chars_into_runs(chars)
runs = []
while head = chars.shift
if runs.empty?
runs << head
elsif runs.last.mergable?(head)
runs[-1] = runs.last + head
else
runs << head
end
end
runs
end
def local_string_insert(haystack, needle, index)
haystack[Range.new(index, index + needle.length - 1)] = String.new(needle)
end
end
end
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