Class: Pdfrb::Font::CMap::Writer

Inherits:
Object
  • Object
show all
Defined in:
lib/pdfrb/font/cmap/writer.rb

Overview

Writes a CMap text file from a mapping of glyph codes to Unicode strings. Used when embedding CID fonts with a subset of glyphs to provide /ToUnicode CMap data.

Supports both 1-byte and 2-byte codespaceranges, supplementary Unicode planes (via UTF-16 surrogate pairs), and automatic chunking of bfchar sections (max 100 entries per section per the PDF spec).

Constant Summary collapse

MAX_BFCHAR_ENTRIES = 
100

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cmap_name:, cid_system_info:, mapping:, code_size: 2) ⇒ Writer

Returns a new instance of Writer.

Parameters:

  • cmap_name (String, Symbol) —

    e.g. "Adobe-Identity-UCS"

  • cid_system_info (Hash) —

    with :registry, :ordering, :supplement

  • mapping (Hash<Integer => String>) —

    glyph code → Unicode string

  • code_size (Integer) (defaults to: 2) —

    1 or 2 (bytes per glyph code)



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# File 'lib/pdfrb/font/cmap/writer.rb', line 32

def initialize(cmap_name:, cid_system_info:, mapping:, code_size: 2)
  @cmap_name = cmap_name.to_s
  @cid_system_info = cid_system_info
  @mapping = mapping
  @code_size = code_size
end

Instance Attribute Details

#cid_system_info ⇒ Object (readonly)

Returns the value of attribute cid_system_info.



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# File 'lib/pdfrb/font/cmap/writer.rb', line 26

def cid_system_info
  @cid_system_info
end

#cmap_name ⇒ Object (readonly)

Returns the value of attribute cmap_name.



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# File 'lib/pdfrb/font/cmap/writer.rb', line 26

def cmap_name
  @cmap_name
end

#mapping ⇒ Object (readonly)

Returns the value of attribute mapping.



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# File 'lib/pdfrb/font/cmap/writer.rb', line 26

def mapping
  @mapping
end

Class Method Details

.write(mapping, name: "Adobe-Identity-UCS") ⇒ Object 



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# File 'lib/pdfrb/font/cmap/writer.rb', line 15

def self.write(mapping, name: "Adobe-Identity-UCS")
  str_mapping = mapping.transform_values { |cp| [cp].pack("U") }
  new(
    cmap_name: name,
    cid_system_info: { registry: "Adobe", ordering: "UCS", supplement: 0 },
    mapping: str_mapping,
    code_size: 1,
  ).to_s
end

Instance Method Details

#to_s ⇒ Object 



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# File 'lib/pdfrb/font/cmap/writer.rb', line 39

def to_s
  buffer = +""
  emit_header(buffer)
  emit_codespacerange(buffer)
  emit_bfchar(buffer)
  emit_footer(buffer)
  buffer.force_encoding(::Encoding::BINARY)
end