Class: Prawn::Fonts::TTF

Inherits:
Prawn::Font show all
Defined in:
lib/prawn/fonts/ttf.rb

Overview

Note:

You shouldn’t use this class directly.

TrueType font.

Direct Known Subclasses

DFont, OTF, TTC

Defined Under Namespace

Classes: Error, FullFontSubsetsCollection, NoPostscriptName, NoUnicodeCMap

Constant Summary

Constants inherited from Prawn::Font

Prawn::Font::AFM, Prawn::Font::DFont, Prawn::Font::TTC, Prawn::Font::TTF

Instance Attribute Summary collapse

Attributes inherited from Prawn::Font

#family, #name, #options

Instance Method Summary collapse

Methods inherited from Prawn::Font

#add_to_current_page, #ascender, #descender, #eql?, font_format, #hash, #height, #height_at, #identifier_for, #inspect, #line_gap, load, #normalize_encoding!

Constructor Details

#initialize(document, name, options = {}) ⇒ TTF

Returns a new instance of TTF.

Parameters:

  • document (Prawn::Document)
  • name (String) —

    font file path

  • options (Hash) (defaults to: {})

Options Hash (options):

  • :family (String)
  • :style (Symbol) 


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# File 'lib/prawn/fonts/ttf.rb', line 134

def initialize(document, name, options = {})
  super

  @ttf = read_ttf_file
  @subsets =
    if full_font_embedding
      FullFontSubsetsCollection.new(@ttf)
    else
      TTFunk::SubsetCollection.new(@ttf)
    end
  @italic_angle = nil

  @attributes = {}
  @bounding_boxes = {}
  @char_widths = {}
  @has_kerning_data = @ttf.kerning.exists? && @ttf.kerning.tables.any?

  @ascender = Integer(@ttf.ascent * scale_factor)
  @descender = Integer(@ttf.descent * scale_factor)
  @line_gap = Integer(@ttf.line_gap * scale_factor)
end

Instance Attribute Details

#subsets ⇒ Object (readonly)

Returns the value of attribute subsets.



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# File 'lib/prawn/fonts/ttf.rb', line 58

def subsets
  @subsets
end

#ttf ⇒ TTFunk::File (readonly)

TTFunk font.

Returns:

  • (TTFunk::File) 


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# File 'lib/prawn/fonts/ttf.rb', line 57

def ttf
  @ttf
end

Instance Method Details

#basename ⇒ String

Base name of the font.

Returns:

  • (String) 


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# File 'lib/prawn/fonts/ttf.rb', line 240

def basename
  @basename ||= @ttf.name.postscript_name
end

#bbox ⇒ Array(Number, Number, Number, Number)

The font bbox.

Returns:

  • (Array(Number, Number, Number, Number)) 


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# File 'lib/prawn/fonts/ttf.rb', line 184

def bbox
  @bbox ||= @ttf.bbox.map { |i| Integer(i * scale_factor) }
end

#cap_height ⇒ Number

Returns:

  • (Number) 


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# File 'lib/prawn/fonts/ttf.rb', line 272

def cap_height
  @cap_height ||=
    begin
      height = (@ttf.os2.exists? && @ttf.os2.cap_height) || 0
      height.zero? ? @ascender : height
    end
end

#character_count(str) ⇒ Integer

Returns the number of characters in ‘str` (a UTF-8-encoded string).

Parameters:

  • str (String)

Returns:

  • (Integer) 


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# File 'lib/prawn/fonts/ttf.rb', line 354

def character_count(str)
  str.length
end

#compute_width_of(string, options = {}) ⇒ Number

Compute width of a string at the specified size, optionally with kerning applied.

Parameters:

  • string (String) —

    must be encoded as UTF-8

  • options (Hash{Symbol => any}) (defaults to: {})

Options Hash (options):

  • :size (Number)
  • :kerning (Boolean) — default: false

Returns:

  • (Number) 


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# File 'lib/prawn/fonts/ttf.rb', line 164

def compute_width_of(string, options = {})
  scale = (options[:size] || size) / 1000.0
  if options[:kerning]
    kern(string).reduce(0) { |s, r|
      if r.is_a?(Numeric)
        s - r
      else
        r.reduce(s) { |a, e| a + character_width_by_code(e) }
      end
    } * scale
  else
    string.codepoints.reduce(0) { |s, r|
      s + character_width_by_code(r)
    } * scale
  end
end

#encode_text(text, options = {}) ⇒ Array<Array(0, (String, Array)>]

Perform any changes to the string that need to happen before it is rendered to the canvas. Returns an array of subset “chunks”, where the even-numbered indices are the font subset number, and the following entry element is either a string or an array (for kerned text).

Parameters:

  • text (String) —

    must be in UTF-8 encoding

  • options (Hash{Symbol => any}) (defaults to: {})

Options Hash (options):

  • :kerning (Boolean)

Returns:

  • (Array<Array(0, (String, Array)>]) —

    Array<Array(0, (String, Array)>]



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# File 'lib/prawn/fonts/ttf.rb', line 204

def encode_text(text, options = {})
  text = text.chomp

  if options[:kerning]
    last_subset = nil
    kern(text).reduce([]) do |result, element|
      if element.is_a?(Numeric)
        unless result.last[1].is_a?(Array)
          result.last[1] = [result.last[1]]
        end
        result.last[1] << element
        result
      else
        encoded = @subsets.encode(element)

        if encoded.first[0] == last_subset
          result.last[1] << encoded.first[1]
          encoded.shift
        end

        if encoded.any?
          last_subset = encoded.last[0]
          result + encoded
        else
          result
        end
      end
    end
  else
    @subsets.encode(text.unpack('U*'))
  end
end

#family_class ⇒ Number

Returns:

  • (Number) 


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# File 'lib/prawn/fonts/ttf.rb', line 290

def family_class
  @family_class ||= ((@ttf.os2.exists? && @ttf.os2.family_class) || 0) >> 8
end

#glyph_present?(char) ⇒ Boolean

Does this font has a glyph for the character?

Parameters:

  • char (String)

Returns:

  • (Boolean) 


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# File 'lib/prawn/fonts/ttf.rb', line 345

def glyph_present?(char)
  code = char.codepoints.first
  cmap[code].positive?
end

#has_kerning_data? ⇒ Boolean

Does this font contain kerning data.

Returns:

  • (Boolean) 


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# File 'lib/prawn/fonts/ttf.rb', line 191

def has_kerning_data? # rubocop: disable Naming/PredicateName
  @has_kerning_data
end

#italic_angle ⇒ Number

Returns:

  • (Number) 


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# File 'lib/prawn/fonts/ttf.rb', line 254

def italic_angle
  return @italic_angle if @italic_angle

  if @ttf.postscript.exists?
    raw = @ttf.postscript.italic_angle
    hi = raw >> 16
    low = raw & 0xFF
    hi = -((hi ^ 0xFFFF) + 1) if hi & 0x8000 != 0
    @italic_angle = Float("#{hi}.#{low}")
  else
    @italic_angle = 0
  end

  @italic_angle
end

#normalize_encoding(text) ⇒ String

Normlize text to a compatible encoding.

Parameters:

  • text (String)

Returns:

  • (String) 


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# File 'lib/prawn/fonts/ttf.rb', line 325

def normalize_encoding(text)
  text.encode(::Encoding::UTF_8)
rescue StandardError
  raise Prawn::Errors::IncompatibleStringEncoding,
    "Encoding #{text.encoding} can not be transparently converted to UTF-8. " \
      'Please ensure the encoding of the string you are attempting to use is set correctly'
end

#pdf_flags ⇒ Integer

Returns:

  • (Integer) 


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# File 'lib/prawn/fonts/ttf.rb', line 308

def pdf_flags
  @pdf_flags ||=
    begin
      flags = 0
      flags |= 0x0001 if @ttf.postscript.fixed_pitch?
      flags |= 0x0002 if serif?
      flags |= 0x0008 if script?
      flags |= 0x0040 if italic_angle != 0
      # Assume the font contains at least some non-latin characters
      flags | 0x0004
    end
end

#script? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/prawn/fonts/ttf.rb', line 302

def script?
  @script ||= family_class == 10
end

#serif? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/prawn/fonts/ttf.rb', line 296

def serif?
  @serif ||= [1, 2, 3, 4, 5, 7].include?(family_class)
end

#stem_v ⇒ Number

Returns:

  • (Number) 


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# File 'lib/prawn/fonts/ttf.rb', line 248

def stem_v
  0
end

#to_utf8(text) ⇒ String

Encode text to UTF-8.

Parameters:

  • text (String)

Returns:

  • (String) 


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# File 'lib/prawn/fonts/ttf.rb', line 337

def to_utf8(text)
  text.encode('UTF-8')
end

#unicode? ⇒ true

Does this font support Unicode?

Returns:

  • (true) 


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# File 'lib/prawn/fonts/ttf.rb', line 63

def unicode?
  true
end

#x_height ⇒ number

Returns:

  • (number) 


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# File 'lib/prawn/fonts/ttf.rb', line 282

def x_height
  # FIXME: seems like if os2 table doesn't exist, we could
  # just find the height of the lower-case 'x' glyph?
  (@ttf.os2.exists? && @ttf.os2.x_height) || 0
end