Add bin and edit workflow

bin/gems/ttfunk-1.8.0/lib/ttfunk/table/cmap/format04.rb

@@ -0,0 +1,160 @@
+# frozen_string_literal: true
+
+module TTFunk
+  class Table
+    class Cmap
+      # Format 4: Segment mapping to delta values.
+      #
+      # This module conditionally extends {TTFunk::Table::Cmap::Subtable}.
+      module Format04
+        # Language.
+        # @return [Integer]
+        attr_reader :language
+
+        # Code map.
+        # @return [Hash{Integer => Integer}]
+        attr_reader :code_map
+
+        # Encode the encoding record to format 4.
+        #
+        # @param charmap [Hash{Integer => Integer}] a hash mapping character
+        #   codes to glyph IDs from the original font.
+        # @return [Hash]
+        #   * `:charmap` (<tt>Hash{Integer => Hash}</tt>) keys are the characrers in
+        #     `charset`, values are hashes:
+        #     * `:old` (<tt>Integer</tt>) - glyph ID in the original font.
+        #     * `:new` (<tt>Integer</tt>) - glyph ID in the subset font.
+        #     that maps the characters in charmap to a
+        #   * `:subtable` (<tt>String</tt>) - serialized encoding record.
+        #   * `:max_glyph_id` (<tt>Integer</tt>) - maximum glyph ID in the new font.
+        def self.encode(charmap)
+          end_codes = []
+          start_codes = []
+          next_id = 0
+          last = difference = nil
+
+          glyph_map = { 0 => 0 }
+          new_map =
+            charmap.keys.sort.each_with_object({}) do |code, map|
+              old = charmap[code]
+              glyph_map[old] ||= next_id += 1
+              map[code] = { old: old, new: glyph_map[old] }
+
+              delta = glyph_map[old] - code
+              if last.nil? || delta != difference
+                end_codes << last if last
+                start_codes << code
+                difference = delta
+              end
+              last = code
+
+              map
+            end
+
+          end_codes << last if last
+          end_codes << 0xFFFF
+          start_codes << 0xFFFF
+          segcount = start_codes.length
+
+          # build the conversion tables
+          deltas = []
+          range_offsets = []
+          glyph_indices = []
+          offset = 0
+
+          start_codes.zip(end_codes).each_with_index do |(a, b), segment|
+            if a == 0xFFFF
+              # We want the final 0xFFFF code to map to glyph 0.
+              # The glyph index is calculated as glyph = charcode + delta,
+              # which means that delta must be -0xFFFF to map character code
+              # 0xFFFF to glyph 0.
+              deltas << -0xFFFF
+              range_offsets << 0
+              break
+            end
+
+            start_glyph_id = new_map[a][:new]
+
+            if a - start_glyph_id >= 0x8000
+              deltas << 0
+              range_offsets << (2 * (glyph_indices.length + segcount - segment))
+              a.upto(b) { |code| glyph_indices << new_map[code][:new] }
+            else
+              deltas << (-a + start_glyph_id)
+              range_offsets << 0
+            end
+
+            offset += 2
+          end
+
+          # format, length, language
+          subtable = [
+            4, 16 + (8 * segcount) + (2 * glyph_indices.length), 0,
+          ].pack('nnn')
+
+          search_range = 2 * (2**Integer(Math.log(segcount) / Math.log(2)))
+          entry_selector = Integer(Math.log(search_range / 2) / Math.log(2))
+          range_shift = (2 * segcount) - search_range
+          subtable << [
+            segcount * 2, search_range, entry_selector, range_shift,
+          ].pack('nnnn')
+
+          subtable << end_codes.pack('n*') << "\0\0" << start_codes.pack('n*')
+          subtable << deltas.pack('n*') << range_offsets.pack('n*')
+          subtable << glyph_indices.pack('n*')
+
+          { charmap: new_map, subtable: subtable, max_glyph_id: next_id + 1 }
+        end
+
+        # Get glyph ID for character code.
+        #
+        # @param code [Integer] character code.
+        # @return [Integer] glyph ID.
+        def [](code)
+          @code_map[code] || 0
+        end
+
+        # Is this encoding record format supported?
+        #
+        # @return [true]
+        def supported?
+          true
+        end
+
+        private
+
+        def parse_cmap!
+          length, @language, segcount_x2 = read(6, 'nnn')
+          segcount = segcount_x2 / 2
+
+          io.read(6) # skip searching hints
+
+          end_code = read(segcount_x2, 'n*')
+          io.read(2) # skip reserved value
+          start_code = read(segcount_x2, 'n*')
+          id_delta = read_signed(segcount)
+          id_range_offset = read(segcount_x2, 'n*')
+
+          glyph_ids = read(length - io.pos + @offset, 'n*')
+
+          @code_map = {}
+
+          end_code.each_with_index do |tail, i|
+            start_code[i].upto(tail) do |code|
+              if (id_range_offset[i]).zero?
+                glyph_id = code + id_delta[i]
+              else
+                index = (id_range_offset[i] / 2) + (code - start_code[i]) - (segcount - i)
+                # Because some TTF fonts are broken
+                glyph_id = glyph_ids[index] || 0
+                glyph_id += id_delta[i] if glyph_id != 0
+              end
+
+              @code_map[code] = glyph_id & 0xFFFF
+            end
+          end
+        end
+      end
+    end
+  end
+end