Class: Prawn::Font::Metrics::TTF

Inherits:
Prawn::Font::Metrics show all
Defined in:
lib/prawn/font/metrics.rb

Overview

:nodoc:

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Prawn::Font::Metrics

[], data, #font_height, #string_height

Methods included from Wrapping

#naive_wrap

Constructor Details

#initialize(font) ⇒ TTF

Returns a new instance of TTF.



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# File 'lib/prawn/font/metrics.rb', line 255

def initialize(font)
  @ttf = ::Font::TTF::File.open(font,"rb")
  @attributes       = {}
  @glyph_widths     = {}
  @bounding_boxes   = {} 
  @char_widths      = {}   
  @has_kerning_data = !kern_pairs_table.empty?    
end

Instance Attribute Details

#ttf ⇒ Object

Returns the value of attribute ttf.



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# File 'lib/prawn/font/metrics.rb', line 253

def ttf
  @ttf
end

Instance Method Details

#ascender ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 345

def ascender
  Integer(@ttf.get_table(:hhea).ascender * scale_factor)
end

#basename ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 357

def basename
  return @basename if @basename
  ps_name = ::Font::TTF::Table::Name::NameRecord::POSTSCRIPT_NAME

  @ttf.get_table(:name).name_records.each do |rec|
    @basename = rec.utf8_str.to_sym if rec.name_id == ps_name            
  end
  @basename
end

#bbox ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 338

def bbox
  head = @ttf.get_table(:head)
  [:x_min, :y_min, :x_max, :y_max].map do |atr| 
    Integer(head.send(atr)) * scale_factor
  end
end

#cmap ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 264

def cmap
  @cmap ||= enc_table.charmaps
end

#convert_text(text, options) ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 411

def convert_text(text,options)
  text = text.chomp
  if options[:kerning] 
    kern(text)         
  else     
   unicode_codepoints = text.unpack("U*")
    glyph_codes = unicode_codepoints.map { |u| 
      enc_table.get_glyph_id_for_unicode(u)
    }
    text = glyph_codes.pack("n*")
  end
end

#descender ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 349

def descender
  Integer(@ttf.get_table(:hhea).descender * scale_factor)
end

#enc_table ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 367

def enc_table
  @enc_table ||= @ttf.get_table(:cmap).encoding_tables.find do |t|
    t.class == ::Font::TTF::Table::Cmap::EncodingTable4
  end
end

#glyph_widths ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 322

def glyph_widths
  glyphs = cmap.values.uniq.sort
  first_glyph = glyphs.shift
  widths = [first_glyph, [Integer(hmtx[first_glyph][0] * scale_factor)]]
  prev_glyph = first_glyph
  glyphs.each do |glyph|
    unless glyph == prev_glyph + 1
      widths << glyph
      widths << []
    end
    widths.last << Integer(hmtx[glyph][0] * scale_factor )
    prev_glyph = glyph
  end
  widths
end

#has_kerning_data? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/prawn/font/metrics.rb', line 403

def has_kerning_data?
  @has_kerning_data 
end

#kern(string, options = {}) ⇒ Object

TODO: NASTY.



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# File 'lib/prawn/font/metrics.rb', line 286

def kern(string,options={})   
  a = []
  
  string.unpack("U*").each do |r|
    if a.last.is_a? Array
      if kern = kern_pairs_table[[cmap[a.last.last], cmap[r]]] 
        kern *= scale_factor
        a << kern << [r]
      else
        a.last << r
      end
    else
      a << [r]
    end
    a
  end
  
  a.map { |r| 
    if options[:skip_conversion]
      r.is_a?(Array) ? r.pack("U*") : r
    else
      i = r.is_a?(Array) ? r.pack("U*") : r 
      x = if i.is_a?(String)
        unicode_codepoints = i.unpack("U*")
        glyph_codes = unicode_codepoints.map { |u| 
          enc_table.get_glyph_id_for_unicode(u)
        }
        glyph_codes.pack("n*")
      else
        i
      end
      x.is_a?(Numeric) ? -x : x 
    end
  }
end

#kern_pairs_table ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 386

def kern_pairs_table
  return @kern_pairs_table if @kern_pairs_table
  
  table = @ttf.get_table(:kern).subtables.find { |s| 
    s.is_a? ::Font::TTF::Table::Kern::KerningSubtable0 }
  
  if table
    @kern_pairs_table = table.kerning_pairs.inject({}) do |h,p|
      h[[p.left, p.right]] = p.value; h
    end
  else
    @kern_pairs_table = {}
  end               
rescue ::Font::TTF::TableMissing
  @kern_pairs_table = {}
end

#line_gap ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 353

def line_gap
  Integer(@ttf.get_table(:hhea).line_gap * scale_factor)   
end

#string_width(string, font_size, options = {}) ⇒ Object 



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# File 'lib/prawn/font/metrics.rb', line 268

def string_width(string, font_size, options = {})
  scale = font_size / 1000.0
  if options[:kerning]
    kern(string,:skip_conversion => true).inject(0) do |s,r|
      if r.is_a? String  
        s + string_width(r, font_size, :kerning => false)
      else 
        s + r * scale
      end
    end
  else
    string.unpack("U*").inject(0) do |s,r|
      s + character_width_by_code(r)
    end * scale
  end
end

#to_unicode_cmap ⇒ Object

TODO: instead of creating a map that contains every glyph in the font,

only include the glyphs that were used



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# File 'lib/prawn/font/metrics.rb', line 375

def to_unicode_cmap
  return @to_unicode if @to_unicode
  @to_unicode = Prawn::Font::CMap.new
  unicode_for_glyph = cmap.invert
  glyphs = unicode_for_glyph.keys.uniq.sort
  glyphs.each do |glyph|
    @to_unicode[unicode_for_glyph[glyph]] = glyph
  end
  @to_unicode
end

#type0? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/prawn/font/metrics.rb', line 407

def type0?
  true
end