Class: Pdfrb::Font::CFF::Index

Inherits:
Object
  • Object
show all
Defined in:
lib/pdfrb/font/cff/index.rb

Overview

CFF INDEX structure (TN5176 s5): count (Card16), offSize (OffSize), offsets (count+1 × offSize bytes, 1-based), then the data items.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(items) ⇒ Index

Returns a new instance of Index.



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# File 'lib/pdfrb/font/cff/index.rb', line 38

def initialize(items)
  @items = items
end

Instance Attribute Details

#items ⇒ Object (readonly)

Returns the value of attribute items.



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# File 'lib/pdfrb/font/cff/index.rb', line 10

def items
  @items
end

Class Method Details

.parse(data, offset) ⇒ Object

Parse an INDEX at offset in data; returns [index, next_offset].



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# File 'lib/pdfrb/font/cff/index.rb', line 14

def self.parse(data, offset)
  count = data.byteslice(offset, 2).unpack1("n")
  return [new([]), offset + 2] if count.zero?

  off_size = data.getbyte(offset + 2)
  offsets_base = offset + 3
  offsets = (0..count).map do |i|
    read_off(data, offsets_base + (i * off_size), off_size)
  end
  data_base = offsets_base + ((count + 1) * off_size)
  items = (0...count).map do |i|
    start = data_base + offsets[i] - 1
    len = offsets[i + 1] - offsets[i]
    data.byteslice(start, len)
  end
  [new(items), data_base + offsets[count] - 1]
end

.read_off(data, pos, size) ⇒ Object 



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# File 'lib/pdfrb/font/cff/index.rb', line 32

def self.read_off(data, pos, size)
  value = 0
  size.times { |i| value = (value * 256) + data.getbyte(pos + i) }
  value
end

Instance Method Details

#[](i) ⇒ Object 



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# File 'lib/pdfrb/font/cff/index.rb', line 50

def [](i)
  @items[i]
end

#each ⇒ Object 



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# File 'lib/pdfrb/font/cff/index.rb', line 42

def each(&)
  @items.each(&)
end

#serialize ⇒ Object

Serialize back to INDEX bytes.



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# File 'lib/pdfrb/font/cff/index.rb', line 55

def serialize
  return [0].pack("n") if @items.empty?

  offsets = [1]
  @items.each { |item| offsets << (offsets.last + item.bytesize) }
  max = offsets.last
  off_size = if max < 0x100
               1
             else
               (if max < 0x10000
                  2
                else
                  (max < 0x1000000 ? 3 : 4)
                end)
             end

  buf = +"".b
  buf << [@items.size].pack("n")
  buf << off_size.chr
  offsets.each do |o|
    off_size.downto(1) { |i| buf << ((o >> (8 * (i - 1))) & 0xFF).chr }
  end
  @items.each { |item| buf << item.b }
  buf
end

#size ⇒ Object 



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# File 'lib/pdfrb/font/cff/index.rb', line 46

def size
  @items.size
end