Merge branch 'fix-maxp-again'

# By Alexander Mankuta (2) and Thomas Dy (1)
* fix-maxp-again:
  Add changelog entry
  Add spec for maxp encoding
  Pass correct glyph mapping when encoding maxp

Author: pointlessone

CHANGELOG.md

@@ -7,6 +7,17 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
 ## [Unreleased]
 
+### Fixed
+
+* `maxp` table encoding
+
+  The table was encoded with the reverse subset indexinx. This resulted in
+  incorrect values being encoded in `maxp` table. This tripped some of the more
+  fussy renderers like Adobe Acrobat, but also constrained implementations such
+  as in most printers.
+
+  Thomas Dy
+
 ## [1.8.0][] - 2024-03-05
 
 ### Fixed

lib/ttfunk/ttf_encoder.rb

@@ -107,7 +107,7 @@ def hhea_table
     end
 
     def maxp_table
-      @maxp_table ||= TTFunk::Table::Maxp.encode(original.maximum_profile, old_to_new_glyph)
+      @maxp_table ||= TTFunk::Table::Maxp.encode(original.maximum_profile, new_to_old_glyph)
     end
 
     def post_table

spec/ttfunk/ttf_encoder_spec.rb

@@ -9,11 +9,12 @@
   let(:original) { TTFunk::File.open(original_font_path) }
 
   let(:encoder_options) { {} }
+  let(:subset_characters) { 'a'..'z' }
   let(:encoder) do
     subset =
       TTFunk::Subset::Unicode.new(original).tap do |sub_set|
         # ASCII lowercase
-        (97..122).each { |char| sub_set.use(char) }
+        subset_characters.each { |char| sub_set.use(char.ord) }
       end
 
     described_class.new(original, subset, encoder_options)
@@ -65,7 +66,16 @@
 
       # verified via the Font-Validator tool at:
       # https://github.com/HinTak/Font-Validator
-      expect(checksum).to eq(0xEEAE9DCF)
+      expect(checksum).to eq(0xEEB49DA9)
+    end
+
+    example_group 'maxp regression', issue: 102 do
+      let(:subset_characters) { ['A'] }
+
+      it 'correctly encodes maxp table for subset' do
+        maxp = new_font.maximum_profile
+        expect(maxp.max_points).to eq 11
+      end
     end
   end
 end