fix

Gemfile

@@ -3,8 +3,6 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
 ruby '2.7.4'
 
-
-gem 'ttfunk', '1.5.1' # https://github.com/prawnpdf/prawn/issues/1144
 gem 'prawn'
 gem 'prawn-svg'
 gem 'front_matter_parser'

Gemfile.lock

@@ -6,17 +6,17 @@ GEM
     css_parser (1.10.0)
       addressable
     front_matter_parser (1.0.1)
-    pdf-core (0.7.0)
-    prawn (2.2.2)
-      pdf-core (~> 0.7.0)
-      ttfunk (~> 1.5)
+    pdf-core (0.9.0)
+    prawn (2.4.0)
+      pdf-core (~> 0.9.0)
+      ttfunk (~> 1.7)
     prawn-svg (0.32.0)
       css_parser (~> 1.6)
       prawn (>= 0.11.1, < 3)
       rexml (~> 3.2)
     public_suffix (4.0.6)
     rexml (3.2.5)
-    ttfunk (1.5.0)
+    ttfunk (1.7.0)
 
 PLATFORMS
   ruby
@@ -25,7 +25,6 @@ DEPENDENCIES
   front_matter_parser
   prawn
   prawn-svg
-  ttfunk (= 1.5)
 
 RUBY VERSION
    ruby 2.7.4p191

build.rb

@@ -2,6 +2,7 @@
 require 'prawn-svg'
 require 'prawn/measurement_extensions'
 require 'front_matter_parser'
+require './fix.rb'
 
 serif = 'fonts/Signifier-Regular.otf'
 sans = 'fonts/Söhne-Buch.otf'

fix.rb

@@ -0,0 +1,43 @@
+# https://github.com/prawnpdf/prawn/issues/1203
+module TTFunk
+  class Table
+    class Cff < TTFunk::Table
+      class Charset < TTFunk::SubTable
+        def encode(mapping)
+          # no offset means no charset was specified (i.e. we're supposed to
+          # use a predefined charset) so there's nothing to encode
+          return '' unless offset
+
+          sids = mapping.keys.sort.map { |new_gid| sid_for(mapping[new_gid]) }
+          sids.delete(0) #.notdef should not be encoded
+          ranges = TTFunk::BinUtils.rangify(sids)
+          range_max = ranges.map(&:last).max
+
+          range_bytes =
+            if range_max.positive?
+              (Math.log2(range_max) / 8).floor + 1
+            else
+              # for cases when there are no sequences at all
+              Float::INFINITY
+            end
+
+          # calculate whether storing the charset as a series of ranges is
+          # more efficient (i.e. takes up less space) vs storing it as an
+          # array of SID values
+          total_range_size = (2 * ranges.size) + (range_bytes * ranges.size)
+          total_array_size = sids.size * element_width(:array_format)
+
+          #if total_array_size <= total_range_size
+            ([format_int(:array_format)] + sids).pack('Cn*')
+          #else
+          #  fmt = range_bytes == 1 ? :range_format8 : :range_format16
+          #  element_fmt = element_format(fmt)
+          #  result = [format_int(fmt)].pack('C')
+          #  ranges.each { |range| result << range.pack(element_fmt) }
+          #  result
+          #end
+        end
+      end
+    end
+  end
+end