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# coding: utf-8
require 'zlib'
class PDF::Reader
module Filter # :nodoc:
# implementation of the Flate (zlib) stream filter
class Flate
def initialize(options = {})
@options = options
end
################################################################################
# Decode the specified data with the Zlib compression algorithm
def filter(data)
deflated = nil
begin
deflated = Zlib::Inflate.new.inflate(data)
rescue Zlib::DataError => e
# by default, Ruby's Zlib assumes the data it's inflating
# is RFC1951 deflated data, wrapped in a RFC1951 zlib container.
# If that fails, then use an undocumented 'feature' to attempt to inflate
# the data as a raw RFC1951 stream.
#
# See
# - http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/243545
# - http://www.gzip.org/zlib/zlib_faq.html#faq38
deflated = Zlib::Inflate.new(-Zlib::MAX_WBITS).inflate(data)
end
Depredict.new(@options).filter(deflated)
rescue Exception => e
# Oops, there was a problem inflating the stream
raise MalformedPDFError,
"Error occured while inflating a compressed stream (#{e.class.to_s}: #{e.to_s})"
end
end
end
end
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