Sha256: 9e95753912c9ba176dbc3cccfb886492e39d18a96328d04a0c1942c4f682ea30
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Size: 1.75 KB
Versions: 23
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Contents
class FormatParser::PDFParser
include FormatParser::IOUtils
# First 9 bytes of a PDF should be in this format, according to:
#
# https://stackoverflow.com/questions/3108201/detect-if-pdf-file-is-correct-header-pdf
#
# There are however exceptions, which are left out for now.
#
PDF_MARKER = /%PDF-1\.[0-8]{1}/
# Page counts have different markers depending on
# the PDF type. There is not a single common way of solving
# this. The only way of solving this correctly is by adding
# different types of PDF's in the specs.
#
COUNT_MARKERS = ['Count ']
EOF_MARKER = '%EOF'
def call(io)
io = FormatParser::IOConstraint.new(io)
return unless safe_read(io, 9) =~ PDF_MARKER
attributes = scan_for_attributes(io)
FormatParser::Document.new(
format: :pdf,
page_count: attributes[:page_count]
)
end
private
# Read ahead bytes until one of % or / is reached.
# A header in a PDF always starts with a /
# The % is to detect the EOF
#
def scan_for_attributes(io)
result = {}
while read = safe_read(io, 1)
case read
when '%'
break if safe_read(io, EOF_MARKER.size) == EOF_MARKER
when '/'
find_page_count(io, result)
end
end
result
end
def find_page_count(io, result)
COUNT_MARKERS.each do |marker|
if safe_read(io, marker.size) == marker
result[:page_count] = read_numbers(io)
end
end
end
# Read ahead bytes until no more numbers are found
# This assumes that the position of io starts at a
# number
def read_numbers(io)
numbers = ''
while c = safe_read(io, 1)
c =~ /\d+/ ? numbers << c : break
end
numbers.to_i
end
FormatParser.register_parser self, natures: :document, formats: :pdf
end
Version data entries
23 entries across 23 versions & 1 rubygems