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# coding: utf-8
# typed: strict
# frozen_string_literal: true
require 'pdf/reader/overlapping_runs_filter'
require 'pdf/reader/zero_width_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 #: Numeric
#: (Array[PDF::Reader::TextRun], Array[Numeric] | PDF::Reader::Rectangle) -> void
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) #: PDF::Reader::Rectangle
@runs = runs #: Array[PDF::Reader::TextRun]
@mean_font_size = mean(@runs.map(&:font_size)) || DEFAULT_FONT_SIZE #: Numeric
@mean_font_size = DEFAULT_FONT_SIZE if @mean_font_size == 0
@median_glyph_width = median(@runs.map(&:mean_character_width)) || 0 #: Numeric
@x_offset = @runs.map(&:x).sort.first || 0 #: Numeric
lowest_y = @runs.map(&:y).sort.first || 0 #: Numeric
@y_offset = lowest_y > 0 ? 0 : lowest_y #: Numeric
@row_count = nil #: Numeric | nil
@col_count = nil #: Numeric | nil
@row_multiplier = nil #: Numeric | nil
@col_multiplier = nil #: Numeric | nil
end
#: () -> String
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
private
#: () -> Numeric
def page_width
@mediabox.width
end
#: () -> Numeric
def page_height
@mediabox.height
end
# given an array of strings, return a new array with empty rows from the
# beginning and end removed.
#
# interesting_rows([ "", "one", "two", "" ])
# => [ "one", "two" ]
#
#: (untyped) -> untyped
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
#: () -> untyped
def row_count
@row_count ||= (page_height / @mean_font_size).floor
end
#: () -> untyped
def col_count
@col_count ||= ((page_width / @median_glyph_width) * 1.05).floor
end
#: () -> untyped
def row_multiplier
@row_multiplier ||= page_height.to_f / row_count.to_f
end
#: () -> untyped
def col_multiplier
@col_multiplier ||= page_width.to_f / col_count.to_f
end
#: (untyped) -> untyped
def mean(collection)
if collection.size == 0
0
else
collection.inject(0) { |accum, v| accum + v} / collection.size.to_f
end
end
#: (untyped) -> untyped
def median(collection)
if collection.size == 0
0
else
collection.sort[(collection.size * 0.5).floor]
end
end
#: (untyped, untyped, untyped) -> untyped
def local_string_insert(haystack, needle, index)
haystack[Range.new(index, index + needle.length - 1)] = String.new(needle)
end
#: (untyped) -> untyped
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
end
end
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