lib/prawn/fonts/afm.rb
# frozen_string_literal: true
# Implements AFM font support for Prawn
#
# Copyright May 2008, Gregory Brown / James Healy. All Rights Reserved.
#
# This is free software. Please see the LICENSE and COPYING files for details.
require_relative '../encoding'
module Prawn
module Fonts
# @private
class AFM < Font
class << self
attr_accessor :hide_m17n_warning
end
self.hide_m17n_warning = false
BUILT_INS = %w[
Courier Helvetica Times-Roman Symbol ZapfDingbats
Courier-Bold Courier-Oblique Courier-BoldOblique
Times-Bold Times-Italic Times-BoldItalic
Helvetica-Bold Helvetica-Oblique Helvetica-BoldOblique
].freeze
def unicode?
false
end
def self.metrics_path
@metrics_path ||=
if ENV['METRICS']
ENV['METRICS'].split(':')
else
[
'.', '/usr/lib/afm',
'/usr/local/lib/afm',
'/usr/openwin/lib/fonts/afm',
"#{Prawn::DATADIR}/fonts"
]
end
end
attr_reader :attributes # :nodoc:
# parse each ATM font file once only
def self.font_data
@font_data ||= SynchronizedCache.new
end
def initialize(document, name, options = {}) # :nodoc:
name ||= options[:family]
unless BUILT_INS.include?(name)
raise Prawn::Errors::UnknownFont,
"#{name} (#{options[:style] || 'normal'}) is not a known font."
end
super
file_name = @name.dup
file_name << '.afm' unless /\.afm$/.match?(file_name)
file_name = file_name[0] == '/' ? file_name : find_font(file_name)
font_data = self.class.font_data[file_name] ||= parse_afm(file_name)
@glyph_widths = font_data[:glyph_widths]
@glyph_table = font_data[:glyph_table]
@bounding_boxes = font_data[:bounding_boxes]
@kern_pairs = font_data[:kern_pairs]
@kern_pair_table = font_data[:kern_pair_table]
@attributes = font_data[:attributes]
@ascender = @attributes['ascender'].to_i
@descender = @attributes['descender'].to_i
@line_gap = Float(bbox[3] - bbox[1]) - (@ascender - @descender)
end
# The font bbox, as an array of integers
#
def bbox
@bbox ||= @attributes['fontbbox'].split(/\s+/).map { |e| Integer(e) }
end
# NOTE: String *must* be encoded as WinAnsi
def compute_width_of(string, options = {}) # :nodoc:
scale = (options[:size] || size) / 1000.0
if options[:kerning]
strings, numbers = kern(string).partition { |e| e.is_a?(String) }
total_kerning_offset = numbers.sum
(unscaled_width_of(strings.join) - total_kerning_offset) * scale
else
unscaled_width_of(string) * scale
end
end
# Returns true if the font has kerning data, false otherwise
#
# rubocop: disable Naming/PredicateName
def has_kerning_data?
@kern_pairs.any?
end
# rubocop: enable Naming/PredicateName
# built-in fonts only work with winansi encoding, so translate the
# string. Changes the encoding in-place, so the argument itself
# is replaced with a string in WinAnsi encoding.
#
def normalize_encoding(text)
text.encode('windows-1252')
rescue ::Encoding::InvalidByteSequenceError,
::Encoding::UndefinedConversionError
raise Prawn::Errors::IncompatibleStringEncoding,
"Your document includes text that's not compatible with the " \
"Windows-1252 character set.\n" \
'If you need full UTF-8 support, use external fonts instead of ' \
"PDF's built-in fonts.\n"
end
def to_utf8(text)
text.encode('UTF-8')
end
# Returns the number of characters in +str+ (a WinAnsi-encoded string).
#
def character_count(str)
str.length
end
# Perform any changes to the string that need to happen
# before it is rendered to the canvas. Returns an array of
# subset "chunks", where each chunk is an array of two elements.
# The first element is the font subset number, and the second
# is either a string or an array (for kerned text).
#
# For Adobe fonts, there is only ever a single subset, so
# the first element of the array is "0", and the second is
# the string itself (or an array, if kerning is performed).
#
# The +text+ parameter must be in WinAnsi encoding (cp1252).
#
def encode_text(text, options = {})
[[0, options[:kerning] ? kern(text) : text]]
end
def glyph_present?(char)
!normalize_encoding(char).nil?
rescue Prawn::Errors::IncompatibleStringEncoding
false
end
private
def register(_subset)
font_dict = {
Type: :Font,
Subtype: :Type1,
BaseFont: name.to_sym
}
# Symbolic AFM fonts (Symbol, ZapfDingbats) have their own encodings
font_dict[:Encoding] = :WinAnsiEncoding unless symbolic?
@document.ref!(font_dict)
end
def symbolic?
attributes['characterset'] == 'Special'
end
def find_font(file)
self.class.metrics_path.find { |f| File.exist? "#{f}/#{file}" } +
"/#{file}"
rescue NoMethodError
raise Prawn::Errors::UnknownFont,
"Couldn't find the font: #{file} in any of:\n" +
self.class.metrics_path.join("\n")
end
def parse_afm(file_name)
data = {
glyph_widths: {},
bounding_boxes: {},
kern_pairs: {},
attributes: {}
}
section = []
File.foreach(file_name) do |line|
case line
when /^Start(\w+)/
section.push Regexp.last_match(1)
next
when /^End(\w+)/
section.pop
next
end
case section
when %w[FontMetrics CharMetrics]
next unless /^CH?\s/.match?(line)
name = line[/\bN\s+(\.?\w+)\s*;/, 1]
data[:glyph_widths][name] = line[/\bWX\s+(\d+)\s*;/, 1].to_i
data[:bounding_boxes][name] = line[/\bB\s+([^;]+);/, 1].to_s.rstrip
when %w[FontMetrics KernData KernPairs]
next unless line =~ /^KPX\s+(\.?\w+)\s+(\.?\w+)\s+(-?\d+)/
data[:kern_pairs][[Regexp.last_match(1), Regexp.last_match(2)]] =
Regexp.last_match(3).to_i
when %w[FontMetrics KernData TrackKern],
%w[FontMetrics Composites]
next
else
parse_generic_afm_attribute(line, data)
end
end
# process data parsed from AFM file to build tables which
# will be used when measuring and kerning text
data[:glyph_table] =
(0..255).map do |i|
data[:glyph_widths][Encoding::WinAnsi::CHARACTERS[i]].to_i
end
character_hash = Hash[
Encoding::WinAnsi::CHARACTERS.zip(
(0..Encoding::WinAnsi::CHARACTERS.size).to_a
)
]
data[:kern_pair_table] =
data[:kern_pairs].each_with_object({}) do |p, h|
h[p[0].map { |n| character_hash[n] }] = p[1]
end
data.each_value(&:freeze)
data.freeze
end
def parse_generic_afm_attribute(line, hash)
line =~ /(^\w+)\s+(.*)/
key = Regexp.last_match(1).to_s.downcase
value = Regexp.last_match(2)
hash[:attributes][key] =
if hash[:attributes][key]
Array(hash[:attributes][key]) << value
else
value
end
end
# converts a string into an array with spacing offsets
# between characters that need to be kerned
#
# String *must* be encoded as WinAnsi
#
def kern(string)
kerned = [[]]
last_byte = nil
string.each_byte do |byte|
k = last_byte && @kern_pair_table[[last_byte, byte]]
if k
kerned << -k << [byte]
else
kerned.last << byte
end
last_byte = byte
end
kerned.map do |e|
e = e.is_a?(Array) ? e.pack('C*') : e
if e.respond_to?(:force_encoding)
e.force_encoding(::Encoding::Windows_1252)
else
e
end
end
end
def unscaled_width_of(string)
string.bytes.reduce(0) do |s, r|
s + @glyph_table[r]
end
end
end
end
end