class Prawn::Font::AFM
@private
Constants
- BUILT_INS
Attributes
Public Class Methods
parse each ATM font file once only
# File lib/prawn/font/afm.rb, line 47 def self.font_data @font_data ||= SynchronizedCache.new end
# File lib/prawn/font/afm.rb, line 31 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
Public Instance Methods
The font bbox, as an array of integers
# File lib/prawn/font/afm.rb, line 77 def bbox @bbox ||= @attributes['fontbbox'].split(/\s+/).map { |e| Integer(e) } end
Returns the number of characters in str
(a WinAnsi-encoded
string).
# File lib/prawn/font/afm.rb, line 122 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).
# File lib/prawn/font/afm.rb, line 138 def encode_text(text, options = {}) [[0, options[:kerning] ? kern(text) : text]] end
# File lib/prawn/font/afm.rb, line 142 def glyph_present?(char) !normalize_encoding(char).nil? rescue Prawn::Errors::IncompatibleStringEncoding false end
Returns true if the font has kerning data, false otherwise
# File lib/prawn/font/afm.rb, line 96 def has_kerning_data? @kern_pairs.any? end
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.
# File lib/prawn/font/afm.rb, line 104 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 TTF fonts instead of PDF's " \ "built-in fonts.\n" end
# File lib/prawn/font/afm.rb, line 116 def to_utf8(text) text.encode('UTF-8') end
# File lib/prawn/font/afm.rb, line 27 def unicode? false end
Private Instance Methods
# File lib/prawn/font/afm.rb, line 167 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
converts a string into an array with spacing offsets bewteen characters that need to be kerned
String must be encoded as WinAnsi
# File lib/prawn/font/afm.rb, line 252 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
# File lib/prawn/font/afm.rb, line 176 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 line =~ /^CH?\s/ 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
# File lib/prawn/font/afm.rb, line 234 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
# File lib/prawn/font/afm.rb, line 150 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
# File lib/prawn/font/afm.rb, line 163 def symbolic? attributes['characterset'] == 'Special' end
# File lib/prawn/font/afm.rb, line 276 def unscaled_width_of(string) string.bytes.inject(0) do |s, r| s + @glyph_table[r] end end