Class: TTFunk::Table::Kern::Format0

Inherits:
Object
  • Object
show all
Includes:
Reader
Defined in:
lib/ttfunk/table/kern/format0.rb

Overview

Format 0 kerning subtable.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attributes = {}) ⇒ Format0

Returns a new instance of Format0.

Parameters:

  • attributes (Hash{Symbol => any}) (defaults to: {})
Source Code
lib/ttfunk/table/kern/format0.rb, line 21
21
def initialize(attributes = {})

22
  @attributes = attributes

23
24
  num_pairs, *pairs = attributes.delete(:data).unpack('nx6n*')

25
26
  @pairs = {}

27
  num_pairs.times do |i|

28
    # sanity check, in case there's a bad length somewhere

29
    break if (i * 3) + 2 > pairs.length

30
31
    left = pairs[i * 3]

32
    right = pairs[(i * 3) + 1]

33
    value = to_signed(pairs[(i * 3) + 2])

34
    @pairs[[left, right]] = value

35
  end

36
end







  



  

    
Instance Attribute Details

    
      
      
      

  

  
    #attributes  ⇒ Hash{Symbol => any}  (readonly)
  

  

  


  

    
Subtable attributes.



  





  


Returns:


    
  
    
  • 
      
      
        (Hash{Symbol => any})
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/kern/format0.rb, line 14

  
14
def attributes

15
  @attributes

16
end







    
      
      
      

  

  
    #pairs  ⇒ Hash{Array(Integer, Integer) => Integer}  (readonly)
  

  

  


  

    
Kerning pairs.



  





  


Returns:


    
  
    
  • 
      
      
        (Hash{Array(Integer, Integer) => Integer})
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/kern/format0.rb, line 18

  
18
def pairs

19
  @pairs

20
end







    
  



  

    
Instance Method Details


    
      

  

  
    #cross_stream?  ⇒ Boolean 
  

  

  


  

    
Is this cross-stream kerning?



  





  


Returns:


    
  
    
  • 
      
      
        (Boolean)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/kern/format0.rb, line 52

  
52
def cross_stream?

53
  @attributes[:cross]

54
end







    
      

  

  
    #horizontal?  ⇒ Boolean 
  

  

  


  

    
Is this horizontal kerning?



  





  


Returns:


    
  
    
  • 
      
      
        (Boolean)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/kern/format0.rb, line 46

  
46
def horizontal?

47
  !vertical?

48
end







    
      

  

  
    #recode(mapping)  ⇒ String 
  

  

  


  

    
Recode this subtable using the specified mapping.



  





  

Parameters:


    
  
    
  • 
      
        mapping
      
      
        (Hash{Integer => Integer})
      
      
      
        —
        
    keys are new glyph IDs,
values are old glyph IDs
    

    
      
    
    • 
  




Returns:


    
  
    
  • 
      
      
        (String)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/kern/format0.rb, line 61

  
61
def recode(mapping)

62
  subset = []

63
  pairs.each do |(left, right), value|

64
    if mapping[left] && mapping[right]

65
      subset << [mapping[left], mapping[right], value]

66
    end

67
  end

68
69
  return if subset.empty?

70
71
  num_pairs = subset.length

72
  search_range = 2 * (2**Integer(Math.log(num_pairs) / Math.log(2)))

73
  entry_selector = Integer(Math.log(search_range / 2) / Math.log(2))

74
  range_shift = (2 * num_pairs) - search_range

75
76
  [

77
    attributes[:version],

78
    (num_pairs * 6) + 14,

79
    attributes[:coverage],

80
    num_pairs,

81
    search_range,

82
    entry_selector,

83
    range_shift,

84
    subset,

85
  ].flatten.pack('n*')

86
end







    
      

  

  
    #vertical?  ⇒ Boolean 
  

  

  


  

    
Is this vertical kerning?



  





  


Returns:


    
  
    
  • 
      
      
        (Boolean)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/kern/format0.rb, line 40

  
40
def vertical?

41
  @attributes[:vertical]

42
end