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Contents
require 'algorithms'
module Tabula
module Whitespace
# Detect whitespace in a document (not yet used in Tabula)
# Described in "Two Geometric Algorithms for layout analysis" (Thomas Breuer)
# http://pdf.aminer.org/000/140/219/two_geometric_algorithms_for_layout_analysis.pdf
def self.find_closest(text_elements, x, y)
text_elements.sort_by { |te|
Math.sqrt((x - te.midpoint[0]) ** 2 + (y - te.midpoint[1]) ** 2)
}.first
end
def self.find_whitespace(text_elements, bounds)
queue = Containers::PriorityQueue.new
queue.push([bounds, text_elements], bounds.width * bounds.height)
rv = []
while !queue.empty?
r, obstacles = queue.pop
if obstacles.empty?
return r
end
pivot = self.find_closest(obstacles, *r.midpoint)
subrectangles = [
ZoneEntity.new(r.top, pivot.right, r.right - pivot.right, pivot.top - r.top),
ZoneEntity.new(r.top, r.left, pivot.left - r.left, pivot.top - r.top),
ZoneEntity.new(pivot.bottom, r.left, pivot.left - r.left, r.bottom - pivot.bottom),
ZoneEntity.new(pivot.bottom, pivot.right, r.right - pivot.right, r.bottom - pivot.bottom)
]
subrectangles.each do |sub_r|
obs = obstacles.select { |s|
s.overlaps?(sub_r)
}
if obs.empty?
rv << sub_r
else
queue.push([sub_r, obs], sub_r.width * sub_r.height)
end
end
end
return rv
end
end
end
Version data entries
8 entries across 8 versions & 1 rubygems