Class: TTFunk::Table::Cmap::Subtable

Inherits:
Object
  • Object
show all
Includes:
Reader
Defined in:
lib/ttfunk/table/cmap/subtable.rb

Overview

Character to Glyph Index encoding record. This class can be extended with a format-specific

See Also:

Constant Summary collapse

ENCODING_MAPPINGS =

Most used encoding mappings.

{
  mac_roman: { platform_id: 1, encoding_id: 0 }.freeze,
  # Use microsoft unicode, instead of generic unicode, for optimal
  # Windows support
  unicode: { platform_id: 3, encoding_id: 1 }.freeze,
  unicode_ucs4: { platform_id: 3, encoding_id: 10 }.freeze,
}.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file, table_start) ⇒ Subtable

Returns a new instance of Subtable.

Parameters:

Source Code
lib/ttfunk/table/cmap/subtable.rb, line 86
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def initialize(file, table_start)

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  @file = file

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  @platform_id, @encoding_id, @offset = read(8, 'nnN')

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  @offset += table_start

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  parse_from(@offset) do

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    @format = read(2, 'n').first

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    case @format

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    when 0 then extend(TTFunk::Table::Cmap::Format00)

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    when 4 then extend(TTFunk::Table::Cmap::Format04)

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    when 6 then extend(TTFunk::Table::Cmap::Format06)

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    when 10 then extend(TTFunk::Table::Cmap::Format10)

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    when 12 then extend(TTFunk::Table::Cmap::Format12)

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    end

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    parse_cmap!

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  end

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end







  



  

    
Instance Attribute Details

    
      
      
      

  

  
    #encoding_id  ⇒ Integere  (readonly)
  

  

  


  

    
Platform-specific encoding ID.



  





  


Returns:


    
  
    
  • 
      
      
        (Integere)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cmap/subtable.rb, line 25

  
25
def encoding_id

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  @encoding_id

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end







    
      
      
      

  

  
    #format  ⇒ Integer  (readonly)
  

  

  


  

    
Record encoding format.



  





  


Returns:


    
  
    
  • 
      
      
        (Integer)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cmap/subtable.rb, line 29

  
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def format

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  @format

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end







    
      
      
      

  

  
    #platform_id  ⇒ Integer  (readonly)
  

  

  


  

    
Platform ID.



  





  


Returns:


    
  
    
  • 
      
      
        (Integer)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cmap/subtable.rb, line 21

  
21
def platform_id

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  @platform_id

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end







    
  



  

    
Class Method Details


    
      

  

  
    .encode(charmap, encoding)  ⇒ Hash 
  

  

  


  

    
Encode encoding record.



  





  

Parameters:


    
  
    
  • 
      
        charmap
      
      
        (Hash{Integer => Integer})
      
      
      
        —
        
    keys are code points in the
used encoding, values are Unicode code points.
    

    
      
    
    • 
  
    
  • 
      
        encoding
      
      
        (Symbol)
      
      
      
        —
        
    

    
      
    
    • 
  




Returns:


    
  
    
  • 
      
      
        (Hash)
      
      
      
        —
        
      
  
    • :platform_id (Integer) - Platform ID of this encoding record.
      • 
  
    • :encoding_id (Integer) - Encodign ID of this encoding record.
      • 
  
    • :subtable (String) - encoded encoding record.
      • 
  
    • :max_glyph_id (Integer) - maximum glyph ID in this encoding
record.
      • 
  
    • :charmap (Hash{Integer => Hash}) - keys are codepoints in this
encoding record, values are hashes:
    
        
      
      • :new - new glyph ID.
        • 
      
      • :old - glyph ID in the original font.
        • 
    
      
  
      • 

    

    
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cmap/subtable.rb, line 56

  
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def self.encode(charmap, encoding)

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  case encoding

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  when :mac_roman

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    result = Format00.encode(charmap)

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  when :unicode

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    result = Format04.encode(charmap)

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  when :unicode_ucs4

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    result = Format12.encode(charmap)

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  else

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    raise NotImplementedError,

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      "encoding #{encoding.inspect} is not supported"

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  end

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  mapping = ENCODING_MAPPINGS[encoding]

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  # platform-id, encoding-id, offset

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  result.merge(

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    platform_id: mapping[:platform_id],

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    encoding_id: mapping[:encoding_id],

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    subtable: [

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      mapping[:platform_id],

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      mapping[:encoding_id],

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      12,

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      result[:subtable],

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    ].pack('nnNA*'),

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  )

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end







    
  


  

    
Instance Method Details


    
      

  

  
    #[](_code)  ⇒ Integer 
  

  

  


  

    
Get glyph ID for character code.



  





  

Parameters:


    
  
    
  • 
      
        _code
      
      
        (Integer)
      
      
      
        —
        
    character code.
    

    
      
    
    • 
  




Returns:


    
  
    
  • 
      
      
        (Integer)
      
      
      
        —
        
    glyph ID.
    

    
      
    
    • 
  



Raises:


    
  
    
  • 
      
      
        (NotImplementedError)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cmap/subtable.rb, line 125

  
125
def [](_code)

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  raise NotImplementedError, "cmap format #{@format} is not supported"

127
end







    
      

  

  
    #supported?  ⇒ Boolean 
  

  

  


  

    
Is this encoding record format supported?



  





  


Returns:


    
  
    
  • 
      
      
        (Boolean)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cmap/subtable.rb, line 117

  
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def supported?

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  false

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end







    
      

  

  
    #unicode?  ⇒ Boolean 
  

  

  


  

    
Is this an encoding record for Unicode?



  





  


Returns:


    
  
    
  • 
      
      
        (Boolean)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/cmap/subtable.rb, line 109

  
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def unicode?

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  (platform_id == 3 && (encoding_id == 1 || encoding_id == 10) && format != 0) ||

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    (platform_id.zero? && format != 0)

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end