class HexaPDF::Font::Type1Wrapper

This class wraps a generic Type1 font object and provides the methods needed for working with the font in a PDF context.

Constants

VALID_ENCODING_NAMES

Array of valid encoding names in PDF

Attributes

pdf_object[R]

Returns the PDF object associated with the wrapper.

wrapped_font[R]

Returns the wrapped Type1 font object.

Public Class Methods

new(document, font, pdf_object: nil, custom_encoding: false) click to toggle source

Creates a new Type1Wrapper object wrapping the Type1 font.

The optional argument pdf_object can be used to set the PDF font object that this wrapper should be associated with. If no object is set, a suitable one is automatically created.

If pdf_object is provided, the PDF object's encoding is used. Otherwise, the WinAnsiEncoding or, for 'Special' fonts, the font's internal encoding is used. The optional argument custom_encoding can be set to true so that a custom encoding is used (only respected if pdf_object is not provided).

# File lib/hexapdf/font/type1_wrapper.rb, line 118
def initialize(document, font, pdf_object: nil, custom_encoding: false)
  @wrapped_font = font
  @pdf_object = pdf_object || create_pdf_object(document)
  @missing_glyph_callable = document.config['font.on_missing_glyph']

  if pdf_object
    @encoding = pdf_object.encoding
    @max_code = 255 # Encoding is not modified
  elsif custom_encoding
    @encoding = Encoding::Base.new
    @encoding.code_to_name[32] = :space
    @max_code = 32 # 32 = space
  elsif @wrapped_font.metrics.character_set == 'Special'
    @encoding = @wrapped_font.encoding
    @max_code = 255 # Encoding is not modified
  else
    @encoding = Encoding.for_name(:WinAnsiEncoding)
    @max_code = 255 # Encoding is not modified
  end

  @zapf_dingbats_opt = {zapf_dingbats: (@wrapped_font.font_name == 'ZapfDingbats')}
  @name_to_glyph = {}
  @codepoint_to_glyph = {}
  @encoded_glyphs = {}
end

Public Instance Methods

decode_utf8(str) click to toggle source

Returns an array of glyph objects representing the characters in the UTF-8 encoded string.

If a Unicode codepoint is not available as glyph object, it is tried to map the codepoint using the font's internal encoding. This is useful, for example, for the ZapfDingbats font to use ASCII characters for accessing the glyphs.

# File lib/hexapdf/font/type1_wrapper.rb, line 172
def decode_utf8(str)
  str.codepoints.map! do |c|
    @codepoint_to_glyph[c] ||=
      begin
        name = Encoding::GlyphList.unicode_to_name(+'' << c, **@zapf_dingbats_opt)
        if @wrapped_font.metrics.character_set == 'Special' &&
            (name == :'.notdef' || !@wrapped_font.metrics.character_metrics.key?(name))
          name = @encoding.name(c)
        end
        name = +"u" << c.to_s(16).rjust(6, '0') if name == :'.notdef'
        glyph(name)
      end
  end
end
encode(glyph) click to toggle source

Encodes the glyph and returns the code string.

# File lib/hexapdf/font/type1_wrapper.rb, line 188
def encode(glyph)
  @encoded_glyphs[glyph.name] ||=
    begin
      if glyph.name == @wrapped_font.missing_glyph_id
        raise HexaPDF::Error, "Glyph for #{glyph.str.inspect} missing"
      end
      code = @encoding.code(glyph.name)
      if code
        code.chr.freeze
      elsif @max_code < 255
        @max_code += 1
        @encoding.code_to_name[@max_code] = glyph.name
        @max_code.chr.freeze
      else
        raise HexaPDF::Error, "Type1 encoding has no codepoint for #{glyph.name}"
      end
    end
end
font_type() click to toggle source

Returns the type of the font, i.e. :Type1.

# File lib/hexapdf/font/type1_wrapper.rb, line 145
def font_type
  :Type1
end
glyph(name) click to toggle source

Returns a Glyph object for the given glyph name.

# File lib/hexapdf/font/type1_wrapper.rb, line 155
def glyph(name)
  @name_to_glyph[name] ||=
    begin
      str = Encoding::GlyphList.name_to_unicode(name, **@zapf_dingbats_opt)
      if @wrapped_font.metrics.character_metrics.key?(name)
        Glyph.new(@wrapped_font, name, str)
      else
        @missing_glyph_callable.call(str, font_type, @wrapped_font)
      end
    end
end
scaling_factor() click to toggle source

Returns 1 since all Type1 fonts use 1000 units for the em-square.

# File lib/hexapdf/font/type1_wrapper.rb, line 150
def scaling_factor
  1
end

Private Instance Methods

create_pdf_object(document) click to toggle source

Creates a PDF object representing the wrapped font for the given PDF document.

# File lib/hexapdf/font/type1_wrapper.rb, line 213
def create_pdf_object(document)
  fd = document.wrap({Type: :FontDescriptor,
                      FontName: @wrapped_font.font_name.intern,
                      FontWeight: @wrapped_font.weight_class,
                      FontBBox: @wrapped_font.bounding_box,
                      ItalicAngle: @wrapped_font.italic_angle || 0,
                      Ascent: @wrapped_font.ascender || 0,
                      Descent: @wrapped_font.descender || 0,
                      CapHeight: @wrapped_font.cap_height,
                      XHeight: @wrapped_font.x_height,
                      StemH: @wrapped_font.dominant_horizontal_stem_width,
                      StemV: @wrapped_font.dominant_vertical_stem_width || 0})
  fd.flag(:fixed_pitch) if @wrapped_font.metrics.is_fixed_pitch
  fd.flag(@wrapped_font.metrics.character_set == 'Special' ? :symbolic : :nonsymbolic)
  fd.must_be_indirect = true

  dict = document.wrap({Type: :Font, Subtype: :Type1,
                        BaseFont: @wrapped_font.font_name.intern,
                        FontDescriptor: fd})
  dict.font_wrapper = self

  document.register_listener(:complete_objects) do
    min, max = @encoding.code_to_name.keys.minmax
    dict[:FirstChar] = min
    dict[:LastChar] = max
    dict[:Widths] = (min..max).map {|code| glyph(@encoding.name(code)).width }

    if VALID_ENCODING_NAMES.include?(@encoding.encoding_name)
      dict[:Encoding] = @encoding.encoding_name
    elsif @encoding != @wrapped_font.encoding
      differences = [min]
      (min..max).each {|code| differences << @encoding.name(code) }
      dict[:Encoding] = {Differences: differences}
    end
  end

  dict
end