Class: Fontisan::Woff2::TableTransformer

Inherits:
Object
  • Object
show all
Defined in:
lib/fontisan/woff2/table_transformer.rb

Overview

Table transformer for WOFF2 encoding

[‘Woff2::TableTransformer`](lib/fontisan/woff2/table_transformer.rb) handles table transformations that improve compression in WOFF2. The WOFF2 spec defines transformations for glyf/loca and hmtx tables.

For Phase 2 Milestone 2.1:

  • Architecture is in place for transformations

  • Actual transformation implementations are marked as TODO

  • Tables are copied as-is without transformation

  • This allows valid WOFF2 generation while leaving room for optimization

Future milestones will implement:

  • glyf/loca transformation (combined stream, delta encoding)

  • hmtx transformation (compact representation)

Reference: www.w3.org/TR/WOFF2/#table_tranforms

Examples:

Transform tables for WOFF2

transformer = TableTransformer.new(font)
glyf_data = transformer.transform_table("glyf")

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(font) ⇒ TableTransformer

Initialize transformer with font

Parameters:



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# File 'lib/fontisan/woff2/table_transformer.rb', line 33

def initialize(font)
  @font = font
end

Instance Attribute Details

#font ⇒ Object (readonly)

Returns Font object with table access.

Returns:

  • (Object) —

    Font object with table access



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# File 'lib/fontisan/woff2/table_transformer.rb', line 28

def font
  @font
end

Instance Method Details

#transform_table(tag) ⇒ String?

Transform a table for WOFF2 encoding

For Milestone 2.1, this returns the original table data without transformation. The architecture supports future implementation of actual transformations.

Parameters:

  • tag (String) —

    Table tag

Returns:

  • (String, nil) —

    Transformed (or original) table data



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# File 'lib/fontisan/woff2/table_transformer.rb', line 45

def transform_table(tag)
  case tag
  when "glyf"
    transform_glyf
  when "loca"
    transform_loca
  when "hmtx"
    transform_hmtx
  else
    # No transformation, return original data
    get_table_data(tag)
  end
end

#transformable?(tag) ⇒ Boolean

Check if a table can be transformed

Parameters:

  • tag (String) —

    Table tag

Returns:

  • (Boolean) —

    True if table supports transformation



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# File 'lib/fontisan/woff2/table_transformer.rb', line 63

def transformable?(tag)
  %w[glyf loca hmtx].include?(tag)
end

#transformation_version(_tag) ⇒ Integer

Determine transformation version for a table

For Milestone 2.1, always returns TRANSFORM_NONE since we don’t implement transformations yet.

Parameters:

  • tag (String) —

    Table tag

Returns:

  • (Integer) —

    Transformation version (0 = none)



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# File 'lib/fontisan/woff2/table_transformer.rb', line 74

def transformation_version(_tag)
  # For this milestone, no transformations are applied
  Directory::TRANSFORM_NONE
end