Embedded file support for Prawn documents

lib/prawn.rb

@@ -61,6 +61,7 @@ def verify_options(accepted, actual)
 require_relative 'prawn/images/image'
 require_relative 'prawn/images/jpg'
 require_relative 'prawn/images/png'
+require_relative 'prawn/embedded_files'
 require_relative 'prawn/stamp'
 require_relative 'prawn/soft_mask'
 require_relative 'prawn/security'

lib/prawn/document.rb

@@ -55,6 +55,7 @@ class Document
     include Prawn::Text
     include Prawn::Graphics
     include Prawn::Images
+    include Prawn::EmbeddedFiles
     include Prawn::Stamp
     include Prawn::SoftMask
     include Prawn::TransformationStack

lib/prawn/embedded_files.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module Prawn
+  module EmbeddedFiles
+    # include PDF::Core::EmbeddedFiles
+    # Link to PR (https://github.com/prawnpdf/pdf-core/pull/47)
+
+    def file(src, options = {})
+      path = Pathname.new(src)
+
+      if path.directory?
+        raise ArgumentError, 'Data source can\'t be a directory'
+      elsif path.file?
+        data = path.read
+        options[:name] ||= src
+        options[:creation_date] ||= path.birthtime
+        options[:modification_date] ||= path.mtime
+      else
+        data = src
+      end
+
+      @file_registry ||= {}
+
+      file = EmbeddedFile.new(data, options)
+      file_obj = @file_registry[file.chksum]
+
+      if file_obj.nil?
+        file_obj = file.build_pdf_object(self)
+        @file_registry[file.chksum] = file_obj
+      end
+
+      filespec = Filespec.new(file_obj, options)
+      filespec_obj = filespec.build_pdf_object(self)
+
+      unless filespec.hidden?
+        # Wait for pdf-core PR
+
+        # attach_file(filespec.file_name, filespec_obj)
+      end
+    end
+  end
+end
+
+require_relative 'embedded_files/embedded_file'
+require_relative 'embedded_files/filespec'

lib/prawn/embedded_files/embedded_file.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require 'digest/md5'
+
+module Prawn
+  module EmbeddedFiles
+    class EmbeddedFile
+      attr_reader :chksum
+
+      def initialize(data, options = {})
+        @creation_date = options[:creation_date]
+        unless @creation_date.kind_of?(Time)
+          @creation_date = Time.now.utc
+        end
+
+        @mod_date = options[:modification_date]
+        unless @mod_date.kind_of?(Time)
+          @mod_date = Time.now.utc
+        end
+
+        @chksum = Digest::MD5.digest(data)
+        @data = data
+      end
+
+      def build_pdf_object(document)
+        obj = document.ref!(
+          Type: :EmbeddedFile,
+          Params: {
+            CreationDate: @creation_date,
+            ModDate: @mod_date,
+            CheckSum: PDF::Core::LiteralString.new(@chksum),
+            Size: @data.length
+          }
+        )
+
+        obj << @data
+        obj.stream.compress!
+        obj
+      end
+    end
+  end
+end

lib/prawn/embedded_files/filespec.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module Prawn
+  module EmbeddedFiles
+    class Filespec
+      attr_reader :file_name
+
+      def initialize(file, options = {})
+        name = options[:name] || file.chksum
+
+        @file_name = PDF::Core::LiteralString.new(name)
+
+        if options[:description]
+          desc_str = options[:description].to_s
+          @description = PDF::Core::LiteralString.new(desc_str)
+        end
+
+        @hidden = options[:hidden]
+        @file = file
+      end
+
+      def hidden?
+        @hidden
+      end
+
+      def build_pdf_object(document)
+        obj = document.ref!(
+          Type: :Filespec,
+          F: @file_name,
+          EF: { F: @file },
+          UF: @file_name
+        )
+
+        obj[:Desc] = @description if @description
+        obj
+      end
+    end
+  end
+end