Class: TTFunk::Table::Cff::Charset

Inherits:
SubTable
  • Object
show all
Includes:
Enumerable
Defined in:
lib/ttfunk/table/cff/charset.rb

Overview

CFF Charset

Constant Summary collapse

FIRST_GLYPH_STRING =

First glyph string. This is an implicit glyph present in all charsets.

'.notdef'
ARRAY_FORMAT =

Format 0.

0
RANGE_FORMAT_8 =

Format 1.

1
RANGE_FORMAT_16 =

Format 2.

2
ISO_ADOBE_CHARSET_ID =

Predefined ISOAdobe charset ID.

0
EXPERT_CHARSET_ID =

Predefined Expert charset ID.

1
EXPERT_SUBSET_CHARSET_ID =

Predefined Expert Subset charset ID.

2
DEFAULT_CHARSET_ID =

Default charset ID.

ISO_ADOBE_CHARSET_ID

Instance Attribute Summary collapse

Attributes inherited from SubTable

#file, #table_offset

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from SubTable

#eot?, #read

Constructor Details

#initialize(top_dict, file, offset = nil, length = nil) ⇒ Charset #initialize(top_dict, file, charset_id) ⇒ Charset

Returns a new instance of Charset.

Overloads:

  • #initialize(top_dict, file, offset = nil, length = nil) ⇒ Charset

    Parameters:

    • top_dict (TTFunk::Table:Cff::TopDict)
    • file (TTFunk::File)
    • offset (Integer) (defaults to: nil)
    • length (Integer) (defaults to: nil)
  • #initialize(top_dict, file, charset_id) ⇒ Charset

    Parameters:

    • top_dict (TTFunk::Table:Cff::TopDict)
    • file (TTFunk::File)
    • charset_id (Integer) —

      0, 1, or 2

Source Code
lib/ttfunk/table/cff/charset.rb, line 92
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def initialize(top_dict, file, offset_or_id = nil, length = nil)

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  @top_dict = top_dict

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  @offset_or_id = offset_or_id || DEFAULT_CHARSET_ID

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  if offset

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    super(file, offset, length)

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  else

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    @items_count = self.class.strings_for_charset_id(offset_or_id).size

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  end

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end







  



  

    
Instance Attribute Details

    
      
      
      

  

  
    #entries  ⇒ TTFunk::OneBasedArray<Integer>, Array<Range<Integer>>  (readonly)
  

  

  


  

    
Encoded entries.



  





  


Returns:







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 61

  
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def entries

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  @entries

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end







    
      
      
      

  

  
    #format  ⇒ Integer  (readonly)
  

  

  


  

    
Encodign format.



  





  


Returns:


    
  
    
  • 
      
      
        (Integer)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 73

  
73
def format

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  @format

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end







    
      
      
      

  

  
    #items_count  ⇒ Integer  (readonly)
  

  

  


  

    
Number of encoded items.



  





  


Returns:


    
  
    
  • 
      
      
        (Integer)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 77

  
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def items_count

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  @items_count

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end







    
      
      
      

  

  
    #length  ⇒ Integer  (readonly)
  

  

  


  

    
Length of encoded charset subtable.



  





  


Returns:


    
  
    
  • 
      
      
        (Integer)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 65

  
65
def length

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  @length

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end







    
      
      
      

  

  
    #offset_or_id  ⇒ Integer  (readonly)
  

  

  


  

    
Offset or charset ID.



  





  


Returns:


    
  
    
  • 
      
      
        (Integer)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 81

  
81
def offset_or_id

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  @offset_or_id

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end







    
      
      
      

  

  
    #top_dict  ⇒ TTFunk::Table::Cff::TopDict  (readonly)
  

  

  


  

    
Top dict.



  





  


Returns:







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 69

  
69
def top_dict

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  @top_dict

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end







    
  



  

    
Class Method Details


    
      

  

  
    .standard_strings  ⇒ TTFunk::OneBasedArray<String> 
  

  

  


  

    
Standard strings defined in the spec that do not need to be defined
in the CFF.



  





  


Returns:







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 39

  
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def standard_strings

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  Charsets::STANDARD_STRINGS

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end







    
      

  

  
    .strings_for_charset_id(charset_id)  ⇒ TTFunk::OneBasedArray<String> 
  

  

  


  

    
Strings for charset ID.



  





  

Parameters:


    
  
    
  • 
      
        charset_id
      
      
        (Integer)
      
      
      
    
    • 
  




Returns:







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 47

  
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def strings_for_charset_id(charset_id)

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  case charset_id

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  when ISO_ADOBE_CHARSET_ID

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    Charsets::ISO_ADOBE

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  when EXPERT_CHARSET_ID

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    Charsets::EXPERT

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  when EXPERT_SUBSET_CHARSET_ID

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    Charsets::EXPERT_SUBSET

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  end

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end







    
  


  

    
Instance Method Details


    
      

  

  
    #[](glyph_id)  ⇒ String? 
  

  

  


  

    
Get character name for glyph index.



  





  

Parameters:


    
  
    
  • 
      
        glyph_id
      
      
        (Integer)
      
      
      
    
    • 
  




Returns:


    
  
    
  • 
      
      
        (String, nil)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 121

  
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def [](glyph_id)

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  return FIRST_GLYPH_STRING if glyph_id.zero?

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  find_string(sid_for(glyph_id))

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end







    
      

  

  
    
      #each {|name| ... } ⇒ void 
    
      #each  ⇒ Enumerator 
    
  

  

  


  

    
Iterate over character names.



  





  

  
Overloads:

  
    
    
      
      
  • 
        #each {|name| ... } ⇒ void 
        
    
  
    
    
    This method returns an undefined value.
    


  
    

    

    
  


    Yield Parameters:
    

      
  
    
    • 
      
        name
      
      
        (String)
      
      
      
    
      • 
  

    


    
      
    • 
    
      
      
  • 
        #each  ⇒ Enumerator 
        
    
  
    
    


  
    

    

    
  


    Returns:
    

      
  
    
    • 
      
      
        (Enumerator)
      
      
      
    
      • 
  

    


    
      
    • 
    
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 110

  
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def each

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  return to_enum(__method__) unless block_given?

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  # +1 adjusts for the implicit .notdef glyph

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  (items_count + 1).times { |i| yield(self[i]) }

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end







    
      

  

  
    #encode(charmap)  ⇒ String 
  

  

  


  

    
Encode charset.



  





  

Parameters:


    
  
    
  • 
      
        charmap
      
      
        (Hash{Integer => Hash})
      
      
      
        —
        
    keys are the charac codes,
values are hashes:
    

      
  
    • :old (Integer) - glyph ID in the original font.
      • 
  
    • :new (Integer) - glyph ID in the subset font.
      • 

    

    
      
    
    • 
  




Returns:


    
  
    
  • 
      
      
        (String)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 149

  
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def encode(charmap)

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  # no offset means no charset was specified (i.e. we're supposed to

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  # use a predefined charset) so there's nothing to encode

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  return '' unless offset

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  sids =

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    charmap

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      .values

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      .reject { |mapping| mapping[:new].zero? }

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      .sort_by { |mapping| mapping[:new] }

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      .map { |mapping| sid_for(mapping[:old]) }

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  ranges = TTFunk::BinUtils.rangify(sids)

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  range_max = ranges.map(&:last).max

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  range_bytes =

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    if range_max.positive?

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      (Math.log2(range_max) / 8).floor + 1

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    else

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      # for cases when there are no sequences at all

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      Float::INFINITY

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    end

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  # calculate whether storing the charset as a series of ranges is

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  # more efficient (i.e. takes up less space) vs storing it as an

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  # array of SID values

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  total_range_size = (2 * ranges.size) + (range_bytes * ranges.size)

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  total_array_size = sids.size * element_width(:array_format)

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  if total_array_size <= total_range_size

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    ([format_int(:array_format)] + sids).pack('Cn*')

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  else

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    fmt = range_bytes == 1 ? :range_format8 : :range_format16

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    element_fmt = element_format(fmt)

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    result = [format_int(fmt)].pack('C')

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    ranges.each { |range| result << range.pack(element_fmt) }

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    result

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  end

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end







    
      

  

  
    #offset  ⇒ Integer? 
  

  

  


  

    
Charset offset in the file.



  





  


Returns:


    
  
    
  • 
      
      
        (Integer, nil)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cff/charset.rb, line 130

  
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def offset

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  # Numbers from 0..2 mean charset IDs instead of offsets. IDs are

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  # basically pre-defined sets of characters.

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  #

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  # In the case of an offset, add the CFF table's offset since the

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  # charset offset is relative to the start of the CFF table. Otherwise

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  # return nil (no offset).

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  if offset_or_id > 2

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    offset_or_id + top_dict.cff_offset

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  end

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end