Core support for embedded files. Name dictionary entry

lib/pdf/core.rb

@@ -4,6 +4,7 @@
 require_relative 'core/annotations'
 require_relative 'core/byte_string'
 require_relative 'core/destinations'
+require_relative 'core/embedded_files'
 require_relative 'core/filters'
 require_relative 'core/stream'
 require_relative 'core/reference'

lib/pdf/core/embedded_files.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module PDF
+  module Core
+    module EmbeddedFiles #:nodoc:
+      # The maximum number of children to fit into a single node in the
+      # EmbeddedFiles tree.
+      NAME_TREE_CHILDREN_LIMIT = 20 #:nodoc:
+
+      # The EmbeddedFiles name tree in the Name dictionary (see
+      # Prawn::Document::Internal#names). This name tree is used to store named
+      # embedded files (PDF spec 3.10.3). (For more on name trees, see section
+      # 3.8.4 in the PDF spec.)
+      #
+      def embedded_files
+        bump_min_version
+
+        names.data[:EmbeddedFiles] ||= ref!(
+          PDF::Core::NameTree::Node.new(self, NAME_TREE_CHILDREN_LIMIT)
+        )
+      end
+
+      # Adds a new embedded file to the EmbeddedFiles name tree
+      # (see #embedded_files). The +reference+ parameter will be converted into
+      # a PDF::Core::Reference if it is not already one.
+      #
+      def add_embedded_file(name, reference)
+        reference = ref!(reference) unless reference.is_a?(PDF::Core::Reference)
+        embedded_files.data.add(name, reference)
+      end
+
+      # Friendly method alias to attach file specifications in the catalog
+      alias attach_file add_embedded_file
+
+      private
+
+      def bump_min_version
+        renderer.min_version(1.4)
+      end
+    end
+  end
+end

spec/pdf/core/embedded_files_spec.rb

@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+class EmbeddedFiles
+  include PDF::Core::EmbeddedFiles
+
+  class InnerRenderer; def min_version(value); end; end
+
+  attr_reader :renderer
+
+  def initialize
+    @size = 0
+    @root = ref!(Type: :Catalog)
+    @renderer = InnerRenderer.new
+  end
+
+  def names
+    @root.data[:Names] ||= ref!(Type: :Names)
+  end
+
+  def ref!(data)
+    @size += 1
+
+    PDF::Core::Reference.new(@size, data)
+  end
+end
+
+RSpec.describe EmbeddedFiles do
+  it 'has an empty catalog object' do
+    t = described_class.new
+    pdf_object = "2 0 obj\n<< /Type /Names\n>>\nendobj\n"
+    expect(t.names.object).to eq pdf_object
+  end
+
+  it 'has an embedded files object with no names' do
+    t = described_class.new
+    pdf_object = "3 0 obj\n<< /Names []\n>>\nendobj\n"
+    expect(t.embedded_files.object).to eq pdf_object
+  end
+
+  it 'has a catalog object with an embedded files reference' do
+    t = described_class.new
+    t.embedded_files
+
+    pdf_object = "2 0 obj\n<< /Type /Names\n/EmbeddedFiles 3 0 R\n>>\nendobj\n"
+    expect(t.names.object).to eq pdf_object
+  end
+
+  it 'has an embedded files object with one name reference' do
+    t = described_class.new
+    file_name = PDF::Core::LiteralString.new('my_file')
+
+    t.add_embedded_file(file_name, t.ref!(Type: :Filespec))
+
+    pdf_object = "4 0 obj\n<< /Names [(my_file) 2 0 R]\n>>\nendobj\n"
+    expect(t.embedded_files.data.size).to eq 1
+    expect(t.embedded_files.object).to eq pdf_object
+  end
+end