67 lines
1.8 KiB
Ruby
67 lines
1.8 KiB
Ruby
# coding: utf-8
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# typed: strict
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# frozen_string_literal: true
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require 'forwardable'
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class PDF::Reader
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# A Hash-like object that wraps the array of glyph widths in a CID font
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# and gives us a nice way to query it for specific widths.
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#
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# there are two ways to calculate a cidfont_glyph_width, that are defined
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# in Section 9.7.4.3 PDF 32000-1:2008 pp 271, the differences are remarked
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# on below. because of these difference that may be contained within the
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# same array, it is a bit difficult to parse this array.
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class CidWidths
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extend Forwardable
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# Graphics State Operators
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def_delegators :@widths, :[], :fetch
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def initialize(default, array)
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@widths = parse_array(default, array.dup)
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end
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private
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def parse_array(default, array)
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widths = Hash.new(default)
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params = []
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while array.size > 0
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params << array.shift
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if params.size == 2 && params.last.is_a?(Array)
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widths.merge! parse_first_form(params.first.to_i, Array(params.last))
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params = []
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elsif params.size == 3
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widths.merge! parse_second_form(params[0].to_i, params[1].to_i, params[2].to_i)
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params = []
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end
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end
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widths
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end
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# this is the form 10 [234 63 234 346 47 234] where width of index 10 is
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# 234, index 11 is 63, etc
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def parse_first_form(first, widths)
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widths.inject({}) { |accum, glyph_width|
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accum[first + accum.size] = glyph_width
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accum
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}
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end
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# this is the form 10 20 123 where all index between 10 and 20 have width 123
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def parse_second_form(first, final, width)
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if first > final
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raise MalformedPDFError, "CidWidths: #{first} must be less than #{final}"
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end
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(first..final).inject({}) { |accum, index|
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accum[index] = width
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accum
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}
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end
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end
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end
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