class PDF::Reader::WidthCalculator::BuiltIn

Type1 fonts can be one of 14 “built in” standard fonts. In these cases, the reader is expected to have it’s own copy of the font metrics. see Section 9.6.2.2, PDF 32000-1:2008, pp 256

Constants

BUILTINS

Public Class Methods

new(font) click to toggle source
# File lib/pdf/reader/width_calculator/built_in.rb, line 23
def initialize(font)
  @font = font
  @@all_metrics ||= PDF::Reader::SynchronizedCache.new

  basefont = extract_basefont(font.basefont)
  metrics_path = File.join(File.dirname(__FILE__), "..","afm","#{basefont}.afm")

  if File.file?(metrics_path)
    @metrics = @@all_metrics[metrics_path] ||= AFM::Font.new(metrics_path)
  else
    raise ArgumentError, "No built-in metrics for #{font.basefont}"
  end
end

Public Instance Methods

glyph_width(code_point) click to toggle source
# File lib/pdf/reader/width_calculator/built_in.rb, line 37
def glyph_width(code_point)
  return 0 if code_point.nil? || code_point < 0

  m = @metrics.char_metrics_by_code[code_point]
  if m.nil?
    names = @font.encoding.int_to_name(code_point)

    m = names.map { |name|
      @metrics.char_metrics[name.to_s]
    }.compact.first
  end

  if m
    m[:wx]
  elsif @font.widths[code_point - 1]
    @font.widths[code_point - 1]
  elsif control_character?(code_point)
    0
  else
    0
  end
end

Private Instance Methods

control_character?(code_point) click to toggle source
# File lib/pdf/reader/width_calculator/built_in.rb, line 62
def control_character?(code_point)
  @font.encoding.int_to_name(code_point).first.to_s[/\Acontrol..\Z/]
end
extract_basefont(font_name) click to toggle source
# File lib/pdf/reader/width_calculator/built_in.rb, line 66
def extract_basefont(font_name)
  if BUILTINS.include?(font_name)
    font_name
  else
    "Times-Roman"
  end
end