Fix PDF/A validation and Adobe Reader display problems due to missing…

… required fields

The /Encoding entry in a Type0 font needs to be a Symbol or a valid CMap
stream. These streams needs additional entries that were missing since
the the recent change for supporting multiple codepoints referencing the
same glyph introduced them.

This lead to a PDF/A validation regression and a display problem on
Adobe Reader.

CHANGELOG.md

@@ -1,10 +1,15 @@
 ## Unreleased
 
+### Added
+
+* [HexaPDF::Type::CMap] for representing CMap streams
+
 ### Fixed
 
 * Checksum calculation for TrueType tables
 * Automatic wrapping of dictionary entry /CIDToGIDMap for CID fonts
 * Performance regression when encoding char codes for TrueType fonts
+* PDF/A validation regression for PDFs using TrueType fonts
 
 
 ## 1.0.1 - 2024-11-04

lib/hexapdf/configuration.rb

@@ -722,6 +722,7 @@ def self.font_on_invalid_glyph(codepoint, invalid_glyph)
                         OutputIntent: 'HexaPDF::Type::OutputIntent',
                         XXDestOutputProfileRef: 'HexaPDF::Type::OutputIntent::DestOutputProfileRef',
                         ExData: 'HexaPDF::Type::Annotations::MarkupAnnotation::ExData',
+                        CMap: 'HexaPDF::Type::CMap',
                       },
                       'object.subtype_map' => {
                         nil => {

lib/hexapdf/font/true_type_wrapper.rb

@@ -381,7 +381,11 @@ def add_encoding_information_cmap(dict, document)
           dict[:Encoding] = :'Identity-H'
         else
           stream = HexaPDF::StreamData.new { HexaPDF::Font::CMap.create_cid_cmap(mapping) }
-          stream_obj = document.add({}, stream: stream)
+          stream_obj = document.add({Type: :CMap,
+                                     CMapName: :Custom,
+                                     CIDSystemInfo: {Registry: "Adobe", Ordering: "Identity",
+                                                     Supplement: 0},
+                                    }, stream: stream)
           stream_obj.set_filter(:FlateDecode)
           dict[:Encoding] = stream_obj
         end

lib/hexapdf/type.rb

@@ -82,6 +82,7 @@ module Type
     autoload(:OptionalContentConfiguration, 'hexapdf/type/optional_content_configuration')
     autoload(:Metadata, 'hexapdf/type/metadata')
     autoload(:OutputIntent, 'hexapdf/type/output_intent')
+    autoload(:CMap, 'hexapdf/type/cmap')
 
   end
 

lib/hexapdf/type/cmap.rb

@@ -0,0 +1,58 @@
+# -*- encoding: utf-8; frozen_string_literal: true -*-
+#
+#--
+# This file is part of HexaPDF.
+#
+# HexaPDF - A Versatile PDF Creation and Manipulation Library For Ruby
+# Copyright (C) 2014-2024 Thomas Leitner
+#
+# HexaPDF is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Affero General Public License version 3 as
+# published by the Free Software Foundation with the addition of the
+# following permission added to Section 15 as permitted in Section 7(a):
+# FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
+# THOMAS LEITNER, THOMAS LEITNER DISCLAIMS THE WARRANTY OF NON
+# INFRINGEMENT OF THIRD PARTY RIGHTS.
+#
+# HexaPDF is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
+# License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with HexaPDF. If not, see <http://www.gnu.org/licenses/>.
+#
+# The interactive user interfaces in modified source and object code
+# versions of HexaPDF must display Appropriate Legal Notices, as required
+# under Section 5 of the GNU Affero General Public License version 3.
+#
+# In accordance with Section 7(b) of the GNU Affero General Public
+# License, a covered work must retain the producer line in every PDF that
+# is created or manipulated using HexaPDF.
+#
+# If the GNU Affero General Public License doesn't fit your need,
+# commercial licenses are available at <https://gettalong.at/hexapdf/>.
+#++
+
+require 'hexapdf/stream'
+
+module HexaPDF
+  module Type
+
+    # Represents an embedded CMap file.
+    #
+    # See: PDF2.0 s9.7.5.3
+    class CMap < Stream
+
+      define_type :CMap
+
+      define_field :Type, type: Symbol, required: true, default: type
+      define_field :CMapName, type: Symbol, required: true
+      define_field :CIDSystemInfo, type: :XXCIDSystemInfo, required: true
+      define_field :WMode, type: Integer
+      define_field :UseCMap, type: [Stream, Symbol]
+
+    end
+
+  end
+end