Class: HexaPDF::Font::TrueType::Font

Inherits:
Object
  • Object
show all
Defined in:
lib/hexapdf/font/true_type/font.rb

Overview

Represents a font in the TrueType font file format.

Constant Summary collapse

DEFAULT_CONFIG =

The default configuration:

font.ttf.table_mapping

The default mapping from table tag as symbol to table class name.

font.ttf.unknown_format

Action to take when encountering unknown subtables. Can either be :ignore which ignores them or :raise which raises an error.

{
  'font.true_type.table_mapping' => {
    head: 'HexaPDF::Font::TrueType::Table::Head',
    cmap: 'HexaPDF::Font::TrueType::Table::Cmap',
    hhea: 'HexaPDF::Font::TrueType::Table::Hhea',
    hmtx: 'HexaPDF::Font::TrueType::Table::Hmtx',
    loca: 'HexaPDF::Font::TrueType::Table::Loca',
    maxp: 'HexaPDF::Font::TrueType::Table::Maxp',
    name: 'HexaPDF::Font::TrueType::Table::Name',
    post: 'HexaPDF::Font::TrueType::Table::Post',
    glyf: 'HexaPDF::Font::TrueType::Table::Glyf',
    'OS/2': 'HexaPDF::Font::TrueType::Table::OS2',
    kern: 'HexaPDF::Font::TrueType::Table::Kern',
  },
  'font.true_type.unknown_format' => :ignore,
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io, config: {}) ⇒ Font

Creates a new TrueType font file object for the given IO object.

The config hash can contain configuration options.



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# File 'lib/hexapdf/font/true_type/font.rb', line 82

def initialize(io, config: {})
  @io = io
  @config = DEFAULT_CONFIG.merge(config)
  @tables = {}
end

Instance Attribute Details

#config ⇒ Object (readonly)

The configuration for the TrueType font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 77

def config
  @config
end

#io ⇒ Object (readonly)

The IO stream associated with this file.



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# File 'lib/hexapdf/font/true_type/font.rb', line 74

def io
  @io
end

Instance Method Details

#[](tag) ⇒ Object

Returns the table instance for the given tag (a symbol), or nil if no such table exists.



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# File 'lib/hexapdf/font/true_type/font.rb', line 101

def [](tag)
  return @tables[tag] if @tables.key?(tag)

  entry = directory.entry(tag.to_s.b)
  entry ? @tables[tag] = table_class(tag).new(self, entry) : nil
end

#ascender ⇒ Object

Returns the ascender of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 158

def ascender
  self[:'OS/2'].typo_ascender || self[:hhea].ascent
end

#bounding_box ⇒ Object

Returns the bounding of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 143

def bounding_box
  self[:head].bbox
end

#build(table_overrides = {}) ⇒ Object

Uses Builder to build a font file for this font.

The table_overrides argument can be used to supply mappings from table names (in string form) to raw table data that should override the respective font’s tables.



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# File 'lib/hexapdf/font/true_type/font.rb', line 92

def build(table_overrides = {})
  tables = directory.table_names.each_with_object({}) do |name, hash|
    hash[name] = self[name.to_sym].raw_data
  end
  tables.merge!(table_overrides)
  Builder.build(tables)
end

#cap_height ⇒ Object

Returns the cap height of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 148

def cap_height
  self[:'OS/2'].cap_height
end

#descender ⇒ Object

Returns the descender of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 163

def descender
  self[:'OS/2'].typo_descender || self[:hhea].descent
end

#directory ⇒ Object

Returns the font directory.



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# File 'lib/hexapdf/font/true_type/font.rb', line 109

def directory
  @directory ||= Table::Directory.new(self, io ? Table::Directory::SELF_ENTRY : nil)
end

#dominant_vertical_stem_width ⇒ Object

Returns the dominant width of vertical stems.

Note: This attribute does not actually exist in TrueType fonts, so it is estimated based on the #weight.



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# File 'lib/hexapdf/font/true_type/font.rb', line 176

def dominant_vertical_stem_width
  weight / 5
end

#family_name ⇒ Object

Returns the family name of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 133

def family_name
  self[:name][:font_family].preferred_record
end

#features ⇒ Object

Returns a set of features this font supports.

Features that may be available are for example :kern or :liga.



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# File 'lib/hexapdf/font/true_type/font.rb', line 116

def features
  @features ||= Set.new.tap do |set|
    set << :kern if self[:kern]&.horizontal_kerning_subtable
  end
end

#font_name ⇒ Object

Returns the PostScript font name.



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# File 'lib/hexapdf/font/true_type/font.rb', line 123

def font_name
  self[:name][:postscript_name].preferred_record
end

#full_name ⇒ Object

Returns the full name of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 128

def full_name
  self[:name][:font_name].preferred_record
end

#italic_angle ⇒ Object

Returns the italic angle of the font, in degrees counter-clockwise from the vertical.



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# File 'lib/hexapdf/font/true_type/font.rb', line 168

def italic_angle
  self[:post].italic_angle.to_f
end

#missing_glyph_id ⇒ Object

Returns th glyph ID of the missing glyph, i.e. 0.



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# File 'lib/hexapdf/font/true_type/font.rb', line 201

def missing_glyph_id
  0
end

#strikeout_position ⇒ Object

Returns the distance from the baseline to the top of the strikeout line.



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# File 'lib/hexapdf/font/true_type/font.rb', line 191

def strikeout_position
  self[:'OS/2'].strikeout_position
end

#strikeout_thickness ⇒ Object

Returns the stroke width for the strikeout line.



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# File 'lib/hexapdf/font/true_type/font.rb', line 196

def strikeout_thickness
  self[:'OS/2'].strikeout_size
end

#underline_position ⇒ Object

Returns the distance from the baseline to the top of the underline.



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# File 'lib/hexapdf/font/true_type/font.rb', line 181

def underline_position
  self[:post].underline_position
end

#underline_thickness ⇒ Object

Returns the stroke width for the underline.



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# File 'lib/hexapdf/font/true_type/font.rb', line 186

def underline_thickness
  self[:post].underline_thickness
end

#weight ⇒ Object

Returns the weight of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 138

def weight
  self[:'OS/2'].weight_class || 0
end

#x_height ⇒ Object

Returns the x-height of the font.



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# File 'lib/hexapdf/font/true_type/font.rb', line 153

def x_height
  self[:'OS/2'].x_height
end