lib/ttfunk/table/hmtx.rb in ttfunk-1.5.1 vs lib/ttfunk/table/hmtx.rb in ttfunk-1.6.0

@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 require_relative '../table'
 
 module TTFunk
   class Table
     class Hmtx < Table
@@ -21,16 +23,21 @@
 
       HorizontalMetric = Struct.new(:advance_width, :left_side_bearing)
 
       def for(glyph_id)
         @metrics[glyph_id] ||
-          HorizontalMetric.new(
-            @metrics.last.advance_width,
-            @left_side_bearings[glyph_id - @metrics.length]
-          )
+          metrics_cache[glyph_id] ||=
+            HorizontalMetric.new(
+              @metrics.last.advance_width,
+              @left_side_bearings[glyph_id - @metrics.length]
+            )
       end
 
       private
+
+      def metrics_cache
+        @metrics_cache ||= {}
+      end
 
       def parse!
         @metrics = []
 
         file.horizontal_header.number_of_metrics.times do