Class: Fontisan::Subset::TableSubsetter

Inherits:
Object
  • Object
show all
Defined in:
lib/fontisan/subset/table_subsetter.rb

Overview

Table-specific subsetting dispatcher.

Per-table subsetting logic lives in [TableStrategy] classes (one per OpenType tag). This class:

1. Holds the inputs to a subsetting run (font, mapping, options)
 plus the cross-strategy [SharedState] (glyf/loca data, bbox,
 max advance, color bitmap subsetter cache).
2. Dispatches `subset_table(tag, table)` to the right strategy
 via [TableStrategy.for(tag)].
3. Keeps `subset_<tag>` wrappers for backward compatibility with
 specs that exercise a single strategy in isolation.

Adding a new subsetting strategy does NOT require editing this file — register it in lib/fontisan/subset/table_strategy.rb.

Examples:

Subset a single table

subsetter = TableSubsetter.new(font, mapping, options)
maxp_data = subsetter.subset_table("maxp", font.table("maxp"))

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(font, mapping, options) ⇒ TableSubsetter

Returns a new instance of TableSubsetter.



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# File 'lib/fontisan/subset/table_subsetter.rb', line 37

def initialize(font, mapping, options)
  @font = font
  @mapping = mapping
  @options = options
  @state = SharedState.new
end

Instance Attribute Details

#font ⇒ SfntFont (readonly)

Returns:



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# File 'lib/fontisan/subset/table_subsetter.rb', line 26

def font
  @font
end

#mapping ⇒ GlyphMapping (readonly)

Returns:



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# File 'lib/fontisan/subset/table_subsetter.rb', line 29

def mapping
  @mapping
end

#options ⇒ Options (readonly)

Returns:



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# File 'lib/fontisan/subset/table_subsetter.rb', line 32

def options
  @options
end

#state ⇒ SharedState (readonly)

Returns:



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# File 'lib/fontisan/subset/table_subsetter.rb', line 35

def state
  @state
end

Instance Method Details

#subset_cmap(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 82

def subset_cmap(table)
  subset_table("cmap", table)
end

#subset_glyf(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 74

def subset_glyf(table)
  subset_table("glyf", table)
end

#subset_head(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 94

def subset_head(table)
  subset_table("head", table)
end

#subset_hhea(table, hmtx = nil) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 65

def subset_hhea(table, hmtx = nil)
  _ = hmtx # ignored; the strategy recomputes from source hmtx
  subset_table("hhea", table)
end

#subset_hmtx(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 70

def subset_hmtx(table)
  subset_table("hmtx", table)
end

#subset_loca(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 78

def subset_loca(table)
  subset_table("loca", table)
end

#subset_maxp(table) ⇒ Object

--- Backward-compat wrappers -------------------------------------- Specs and external callers may invoke subset_<tag>(table) directly. Each wrapper delegates to the corresponding strategy.



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# File 'lib/fontisan/subset/table_subsetter.rb', line 61

def subset_maxp(table)
  subset_table("maxp", table)
end

#subset_name(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 90

def subset_name(table)
  subset_table("name", table)
end

#subset_os2(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 98

def subset_os2(table)
  subset_table("OS/2", table)
end

#subset_post(table) ⇒ Object 



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# File 'lib/fontisan/subset/table_subsetter.rb', line 86

def subset_post(table)
  subset_table("post", table)
end

#subset_table(tag, table) ⇒ String

Subset one table by dispatching to its strategy. Unknown tables fall through to [TableStrategy::PassThrough] which preserves the source bytes verbatim.

Parameters:

  • tag (String) —

    OpenType table tag (e.g. "glyf", "CBDT")

  • table (Object) —

    parsed table object

Returns:

  • (String) —

    subset table binary bytes



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# File 'lib/fontisan/subset/table_subsetter.rb', line 51

def subset_table(tag, table)
  TableStrategy.for(tag).call(
    context: subset_context, tag: tag, table: table,
  )
end