Add bin and edit workflow

bin/gems/ttfunk-1.8.0/lib/ttfunk/table/kern/format0.rb

@@ -0,0 +1,90 @@
+# frozen_string_literal: true
+
+require_relative '../../reader'
+
+module TTFunk
+  class Table
+    class Kern
+      # Format 0 kerning subtable.
+      class Format0
+        include Reader
+
+        # Subtable attributes.
+        # @return [Hash{Symbol => any}]
+        attr_reader :attributes
+
+        # Kerning pairs.
+        # @return [Hash{Array(Integer, Integer) => Integer}]
+        attr_reader :pairs
+
+        # @param attributes [Hash{Symbol => any}]
+        def initialize(attributes = {})
+          @attributes = attributes
+
+          num_pairs, *pairs = attributes.delete(:data).unpack('nx6n*')
+
+          @pairs = {}
+          num_pairs.times do |i|
+            # sanity check, in case there's a bad length somewhere
+            break if (i * 3) + 2 > pairs.length
+
+            left = pairs[i * 3]
+            right = pairs[(i * 3) + 1]
+            value = to_signed(pairs[(i * 3) + 2])
+            @pairs[[left, right]] = value
+          end
+        end
+
+        # Is this vertical kerning?
+        # @return [Boolean]
+        def vertical?
+          @attributes[:vertical]
+        end
+
+        # Is this horizontal kerning?
+        # @return [Boolean]
+        def horizontal?
+          !vertical?
+        end
+
+        # Is this cross-stream kerning?
+        # @return [Boolean]
+        def cross_stream?
+          @attributes[:cross]
+        end
+
+        # Recode this subtable using the specified mapping.
+        #
+        # @param mapping [Hash{Integer => Integer}] keys are new glyph IDs,
+        #   values are old glyph IDs
+        # @return [String]
+        def recode(mapping)
+          subset = []
+          pairs.each do |(left, right), value|
+            if mapping[left] && mapping[right]
+              subset << [mapping[left], mapping[right], value]
+            end
+          end
+
+          return if subset.empty?
+
+          num_pairs = subset.length
+          search_range = 2 * (2**Integer(Math.log(num_pairs) / Math.log(2)))
+          entry_selector = Integer(Math.log(search_range / 2) / Math.log(2))
+          range_shift = (2 * num_pairs) - search_range
+
+          [
+            attributes[:version],
+            (num_pairs * 6) + 14,
+            attributes[:coverage],
+            num_pairs,
+            search_range,
+            entry_selector,
+            range_shift,
+            subset,
+          ].flatten.pack('n*')
+        end
+      end
+    end
+  end
+end