Class: Fontisan::Optimizers::SubroutineOptimizer

Inherits:
Object
  • Object
show all
Defined in:
lib/fontisan/optimizers/subroutine_optimizer.rb

Overview

Optimizes subroutine selection and ordering for maximum file size reduction. Uses a greedy algorithm to select the most beneficial patterns while avoiding conflicts, then orders them by frequency for efficient encoding.

Examples:

Basic usage

analyzer = PatternAnalyzer.new
patterns = analyzer.analyze(charstrings)
optimizer = SubroutineOptimizer.new(patterns, max_subrs: 65535)
selected_patterns = optimizer.optimize_selection
ordered_patterns = optimizer.optimize_ordering(selected_patterns)

See Also:

  • docs/SUBROUTINE_ARCHITECTUREdocs/SUBROUTINE_ARCHITECTURE.md

Instance Method Summary collapse

Constructor Details

#initialize(patterns, max_subrs: 65535) ⇒ SubroutineOptimizer

Initialize optimizer with patterns

Parameters:

  • patterns (Array<Pattern>) —

    patterns from analyzer

  • max_subrs (Integer) (defaults to: 65535) —

    maximum number of subroutines (default: 65535)



21
22
23
24
 
# File 'lib/fontisan/optimizers/subroutine_optimizer.rb', line 21

def initialize(patterns, max_subrs: 65535)
  @patterns = patterns
  @max_subrs = max_subrs
end

Instance Method Details

#optimize_nesting(subroutines) ⇒ Array<Pattern>

Check if nesting would be beneficial TODO: Phase 2.1 - check if subroutines contain common patterns

Parameters:

  • subroutines (Array<Pattern>) —

    subroutines to analyze

Returns:

  • (Array<Pattern>) —

    subroutines (unchanged for now)



68
69
70
 
# File 'lib/fontisan/optimizers/subroutine_optimizer.rb', line 68

def optimize_nesting(subroutines)
  subroutines
end

#optimize_ordering(subroutines) ⇒ Array<Pattern>

Optimize subroutine ordering by frequency Higher frequency patterns get lower IDs for more efficient encoding in CFF format.

Parameters:

  • subroutines (Array<Pattern>) —

    subroutines to order

Returns:

  • (Array<Pattern>) —

    ordered subroutines



55
56
57
58
59
60
61
 
# File 'lib/fontisan/optimizers/subroutine_optimizer.rb', line 55

def optimize_ordering(subroutines)
  # Higher frequency = lower ID (shorter encoding)
  # Use same comprehensive sort keys as optimize_selection for consistency
  subroutines.sort_by do |subr|
    [-subr.frequency, -subr.length, subr.glyphs.min, subr.bytes.bytes]
  end
end

#optimize_selection ⇒ Array<Pattern>

Select optimal subset of patterns to subroutinize Uses greedy algorithm: select by highest savings first, checking for conflicts with already selected patterns.

Returns:

  • (Array<Pattern>) —

    selected patterns



31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
 
# File 'lib/fontisan/optimizers/subroutine_optimizer.rb', line 31

def optimize_selection
  selected = []
  # Sort by savings (descending), then by length (descending), then by min glyph ID,
  # then by byte values for complete determinism across platforms
  remaining = @patterns.sort_by do |p|
    [-p.savings, -p.length, p.glyphs.min, p.bytes.bytes]
  end

  remaining.each do |pattern|
    break if selected.length >= @max_subrs
    next if conflicts_with_selected?(pattern, selected)

    selected << pattern
  end

  selected
end