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# frozen_string_literal: true
module TTFunk
class Table
class Cmap
# Format 12: Segmented coverage.
#
# This module conditionally extends {TTFunk::Table::Cmap::Subtable}.
module Format12
# Language.
# @return [Integer]
attr_reader :language
# Code map.
# @return [Hash{Integer => Integer}]
attr_reader :code_map
# Encode the encoding record to format 12.
#
# @param charmap [Hash{Integer => Integer}] a hash mapping character
# codes to glyph IDs from the original font.
# @return [Hash]
# * `:charmap` (<tt>Hash{Integer => Hash}</tt>) keys are the characrers in
# `charset`, values are hashes:
# * `:old` (<tt>Integer</tt>) - glyph ID in the original font.
# * `:new` (<tt>Integer</tt>) - glyph ID in the subset font.
# that maps the characters in charmap to a
# * `:subtable` (<tt>String</tt>) - serialized encoding record.
# * `:max_glyph_id` (<tt>Integer</tt>) - maximum glyph ID in the new font.
def self.encode(charmap)
next_id = 0
glyph_map = { 0 => 0 }
range_firstglyphs = []
range_firstcodes = []
range_lengths = []
last_glyph = last_code = -999
new_map =
charmap.keys.sort.each_with_object({}) do |code, map|
glyph_map[charmap[code]] ||= next_id += 1
map[code] = { old: charmap[code], new: glyph_map[charmap[code]] }
if code > last_code + 1 || glyph_map[charmap[code]] > last_glyph + 1
range_firstcodes << code
range_firstglyphs << glyph_map[charmap[code]]
range_lengths << 1
else
range_lengths.push(range_lengths.pop) + 1
end
last_code = code
last_glyph = glyph_map[charmap[code]]
end
subtable = [
12, 0, 16 + (12 * range_lengths.size), 0, range_lengths.size,
].pack('nnNNN')
range_lengths.each_with_index do |length, i|
firstglyph = range_firstglyphs[i]
firstcode = range_firstcodes[i]
subtable << [
firstcode, firstcode + length - 1, firstglyph,
].pack('NNN')
end
{ charmap: new_map, subtable: subtable, max_glyph_id: next_id + 1 }
end
# Get glyph ID for character code.
#
# @param code [Integer] character code.
# @return [Integer] glyph ID.
def [](code)
@code_map[code] || 0
end
# Is this encoding record format supported?
#
# @return [true]
def supported?
true
end
private
def parse_cmap!
fractional_version, @language, groupcount = read(14, 'nx4NN')
if fractional_version != 0
raise NotImplementedError,
"cmap version 12.#{fractional_version} is not supported"
end
@code_map = {}
(1..groupcount).each do
startchar, endchar, startglyph = read(12, 'NNN')
(0..(endchar - startchar)).each do |offset|
@code_map[startchar + offset] = startglyph + offset
end
end
end
end
end
end
end
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