Class: HexaPDF::Document

Inherits:
Object
  • Object
show all
Defined in:
lib/hexapdf/document.rb,
lib/hexapdf/document/files.rb,
lib/hexapdf/document/fonts.rb,
lib/hexapdf/document/pages.rb,
lib/hexapdf/document/images.rb,
lib/hexapdf/document/layout.rb,
lib/hexapdf/document/destinations.rb

Overview

HexaPDF::Document

Represents a PDF document.

A PDF document essentially consists of (indirect) objects, so the main job of this class is to provide methods for working with these objects. However, since a PDF document may also be incrementally updated and can therefore contain one or more revisions, there are also methods for working with these revisions (see Revisions for details).

Additionally, there are many convenience methods for easily accessing the most important PDF functionality, like encrypting a document (#encrypt), working with digital signatures (#signatures), accessing the interactive form data (#acro_form), working with the pages (#pages), fonts (#fonts) and images (#images).

Note: This class provides the basis for working with a PDF document. The higher PDF functionality is not implemented here but either in the appropriate PDF type classes or in special convenience classes. All this functionality can be accessed via the convenience methods described above.

Available Message Hooks

The document object provides a basic message dispatch system via #register_listener and #dispatch_message.

Following messages are used by HexaPDF itself:

:complete_objects

This message is called before the first step of writing a document. Listeners should complete PDF objects that are missing some information.

For example, the font system uses this message to complete the font objects with information that is only available once all the used glyphs are known.

:before_write

This message is called before a document is actually serialized and written.

Defined Under Namespace

Classes: Destinations, Files, Fonts, Images, Layout, Pages

Constant Summary collapse

UNSET =

:nordoc:

::Object.new

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io: nil, decryption_opts: {}, config: {}) ⇒ Document

Creates a new PDF document, either an empty one or one read from the provided io.

When an IO object is provided and it contains an encrypted PDF file, it is automatically decrypted behind the scenes. The decryption_opts argument has to be set appropriately in this case. In case this is not wanted, the configuration option ‘document.auto_decrypt’ needs to be used.

Options:

io

If an IO object is provided, then this document can read PDF objects from this IO object, otherwise it can only contain created PDF objects.

decryption_opts

A hash with options for decrypting the PDF objects loaded from the IO. The PDF standard security handler expects a :password key to be set to either the user or owner password of the PDF file.

config

A hash with configuration options that is deep-merged into the default configuration (see HexaPDF::DefaultDocumentConfiguration, meaning that direct sub-hashes are merged instead of overwritten.



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# File 'lib/hexapdf/document.rb', line 184

def initialize(io: nil, decryption_opts: {}, config: {})
  @config = Configuration.with_defaults(config)
  @version = '1.2'
  @cache = Hash.new {|h, k| h[k] = {} }
  @listeners = {}

  @revisions = Revisions.from_io(self, io)
  @security_handler = if encrypted? && @config['document.auto_decrypt']
                        Encryption::SecurityHandler.set_up_decryption(self, **decryption_opts)
                      else
                        nil
                      end
end

Instance Attribute Details

#config ⇒ Object (readonly)

The configuration object for the document.

See Configuration for details.



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# File 'lib/hexapdf/document.rb', line 155

def config
  @config
end

#revisions ⇒ Object (readonly)

The revisions of the document.

See Revisions.



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# File 'lib/hexapdf/document.rb', line 160

def revisions
  @revisions
end

Class Method Details

.open(filename, **kwargs) ⇒ Object

:call-seq:

Document.open(filename, **docargs)                   -> doc
Document.open(filename, **docargs) {|doc| block}     -> obj

Creates a new PDF Document object for the given file.

Depending on whether a block is provided, the functionality is different:

  • If no block is provided, the whole file is instantly read into memory and the PDF Document created for it is returned.

  • If a block is provided, the file is opened and a PDF Document is created for it. The created document is passed as an argument to the block and when the block returns the associated file object is closed. The value of the block will be returned.

The block version is useful, for example, when you are dealing with a large file and you only need a small portion of it.

The provided keyword arguments (except io) are passed on unchanged to Document.new.



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# File 'lib/hexapdf/document.rb', line 142

def self.open(filename, **kwargs)
  if block_given?
    File.open(filename, 'rb') do |file|
      yield(new(**kwargs, io: file))
    end
  else
    new(**kwargs, io: StringIO.new(File.binread(filename)))
  end
end

Instance Method Details

#acro_form(create: false) ⇒ Object

Returns the main AcroForm object for dealing with interactive forms.

The meaning of the create argument is detailed at Type::Catalog#acro_form.

See: Type::AcroForm::Form



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# File 'lib/hexapdf/document.rb', line 530

def acro_form(create: false)
  catalog.acro_form(create: create)
end

#add(obj, **wrap_opts) ⇒ Object

:call-seq:

doc.add(obj, **wrap_opts)     -> indirect_object

Adds the object to the document and returns the wrapped indirect object.

The object can either be a native Ruby object (Hash, Array, Integer, …) or a HexaPDF::Object. If it is not the latter, #wrap is called with the object and the additional keyword arguments.

See: #wrap, Revisions#add_object



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# File 'lib/hexapdf/document.rb', line 247

def add(obj, **wrap_opts)
  obj = wrap(obj, **wrap_opts) unless obj.kind_of?(HexaPDF::Object)

  if obj.document? && obj.document != self
    raise HexaPDF::Error, "Can't add object that is already attached to another document"
  end
  obj.document = self

  @revisions.add_object(obj)
end

#cache(pdf_data, key, value = UNSET, update: false) ⇒ Object

Caches and returns the given value or the value of the given block using the given pdf_data and key arguments as composite cache key.

If a cached value already exists and update is false, the cached value is just returned. If update is set to true, an update of the cached value is forced.

This facility can be used to cache expensive operations in PDF objects that are easy to compute again.

Use #clear_cache to clear the cache if necessary.



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# File 'lib/hexapdf/document.rb', line 464

def cache(pdf_data, key, value = UNSET, update: false)
  return @cache[pdf_data][key] if cached?(pdf_data, key) && !update
  @cache[pdf_data][key] = (value == UNSET ? yield : value)
end

#cached?(pdf_data, key) ⇒ Boolean

Returns true if there is a value cached for the composite key consisting of the given pdf_data and key objects.

See: #cache

Returns:

  • (Boolean) 


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# File 'lib/hexapdf/document.rb', line 473

def cached?(pdf_data, key)
  @cache.key?(pdf_data) && @cache[pdf_data].key?(key)
end

#catalog ⇒ Object

Returns the document’s catalog, the root of the object tree.

See: Type::Catalog



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# File 'lib/hexapdf/document.rb', line 571

def catalog
  trailer.catalog
end

#clear_cache(pdf_data = nil) ⇒ Object

Clears all cached data or, if a Object::PDFData object is given, just the cache for this one object.

It is not recommended to clear the whole cache! Better clear the cache for individual PDF objects!

See: #cache, #cached?



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# File 'lib/hexapdf/document.rb', line 484

def clear_cache(pdf_data = nil)
  pdf_data ? @cache[pdf_data].clear : @cache.clear
end

#delete(ref) ⇒ Object

:call-seq:

doc.delete(ref)
doc.delete(oid)

Deletes the indirect object specified by an exact reference or by an object number from the document.

See: Revisions#delete_object



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# File 'lib/hexapdf/document.rb', line 266

def delete(ref)
  @revisions.delete_object(ref)
end

#deref(obj) ⇒ Object

Dereferences the given object.

Returns the object itself if it is not a reference, or the indirect object specified by the reference.



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# File 'lib/hexapdf/document.rb', line 233

def deref(obj)
  obj.kind_of?(Reference) ? object(obj) : obj
end

#destinations ⇒ Object

Returns the Destinations object that provides convenience methods for working with destination objects.



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# File 'lib/hexapdf/document.rb', line 515

def destinations
  @destinations ||= Destinations.new(self)
end

#dispatch_message(name, *args) ⇒ Object

Dispatches the message name with the given arguments to all registered listeners.

See the main Document documentation for an overview of messages that are used by HexaPDF itself.

See: register_listener



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# File 'lib/hexapdf/document.rb', line 448

def dispatch_message(name, *args)
  @listeners[name]&.each {|obj| obj.call(*args) }
end

#each(only_current: true, only_loaded: false, &block) ⇒ Object

:call-seq:

doc.each(only_current: true, only_loaded: false) {|obj| block }
doc.each(only_current: true, only_loaded: false) {|obj, rev| block }
doc.each(only_current: true, only_loaded: false)                       -> Enumerator

Yields every object and the revision it is in.

If only_current is true, only the current version of each object is yielded, otherwise all objects from all revisions. Note that it is normally not necessary or useful to retrieve all objects from all revisions and if it is still done that care has to be taken to avoid an invalid document state.

If only_loaded is true, only the already loaded objects are yielded.

For details see Revisions#each_object



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# File 'lib/hexapdf/document.rb', line 422

def each(only_current: true, only_loaded: false, &block)
  @revisions.each_object(only_current: only_current, only_loaded: only_loaded, &block)
end

#encrypt(name: :Standard, **options) ⇒ Object

Encrypts the document.

Encryption is done by setting up a security handler for this purpose and populating the trailer’s Encrypt dictionary accordingly. The actual encryption, however, is only done when writing the document.

The security handler used for encrypting is selected via the name argument. All other arguments are passed on the security handler.

If the document should not be encrypted, the name argument has to be set to nil. This removes the security handler and deletes the trailer’s Encrypt dictionary.

See: Encryption::SecurityHandler#set_up_encryption and Encryption::StandardSecurityHandler::EncryptionOptions for possible encryption options.



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# File 'lib/hexapdf/document.rb', line 615

def encrypt(name: :Standard, **options)
  if name.nil?
    trailer.delete(:Encrypt)
    @security_handler = nil
  else
    @security_handler = Encryption::SecurityHandler.set_up_encryption(self, name, **options)
  end
end

#encrypted? ⇒ Boolean

Returns true if the document is encrypted.

Returns:

  • (Boolean) 


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# File 'lib/hexapdf/document.rb', line 597

def encrypted?
  !trailer[:Encrypt].nil?
end

#files ⇒ Object

Returns the Files object that provides convenience methods for working with embedded files.



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# File 'lib/hexapdf/document.rb', line 503

def files
  @files ||= Files.new(self)
end

#fonts ⇒ Object

Returns the Fonts object that provides convenience methods for working with the fonts used in the PDF file.



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# File 'lib/hexapdf/document.rb', line 509

def fonts
  @fonts ||= Fonts.new(self)
end

#images ⇒ Object

Returns the Images object that provides convenience methods for working with images (e.g. adding them to the PDF or listing them).



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# File 'lib/hexapdf/document.rb', line 498

def images
  @images ||= Images.new(self)
end

#import(obj) ⇒ Object

:call-seq:

doc.import(obj)     -> imported_object

Imports the given object from a different HexaPDF::Document instance and returns the imported object.

If the same argument is provided in multiple invocations, the import is done only once and the previously imported object is returned.

See: Importer



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# File 'lib/hexapdf/document.rb', line 280

def import(obj)
  source = (obj.kind_of?(HexaPDF::Object) ? obj.document : nil)
  HexaPDF::Importer.for(self).import(obj, source: source)
end

#inspect ⇒ Object

:nodoc:



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# File 'lib/hexapdf/document.rb', line 736

def inspect #:nodoc:
  "<#{self.class.name}:#{object_id}>"
end

#layout ⇒ Object

Returns the Layout object that provides convenience methods for working with the HexaPDF::Layout classes for document layout.



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# File 'lib/hexapdf/document.rb', line 521

def layout
  @layout ||= Layout.new(self)
end

#object(ref) ⇒ Object

:call-seq:

doc.object(ref)    -> obj or nil
doc.object(oid)    -> obj or nil

Returns the current version of the indirect object for the given exact reference (see Reference) or for the given object number.

For references to unknown objects, nil is returned but free objects are represented by a PDF Null object, not by nil!

See: Revisions#object



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# File 'lib/hexapdf/document.rb', line 209

def object(ref)
  @revisions.object(ref)
end

#object?(ref) ⇒ Boolean

:call-seq:

doc.object?(ref)    -> true or false
doc.object?(oid)    -> true or false

Returns true if the the document contains an indirect object for the given exact reference (see Reference) or for the given object number.

Even though this method might return true for some references, #object may return nil because this method takes all revisions into account. Also see the discussion on #each for more information.

See: Revisions#object?

Returns:

  • (Boolean) 


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# File 'lib/hexapdf/document.rb', line 225

def object?(ref)
  @revisions.object?(ref)
end

#optional_content ⇒ Object

Returns the main object for working with optional content (a.k.a. layers).

See: Type::Catalog#optional_content



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# File 'lib/hexapdf/document.rb', line 544

def optional_content
  catalog.optional_content
end

#outline ⇒ Object

Returns the entry object to the document outline (a.k.a. bookmarks).

See: Type::Outline



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# File 'lib/hexapdf/document.rb', line 537

def outline
  catalog.outline
end

#pages ⇒ Object

Returns the Pages object that provides convenience methods for working with the pages of the PDF file.

See: Pages, Type::PageTreeNode



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# File 'lib/hexapdf/document.rb', line 492

def pages
  @pages ||= Pages.new(self)
end

#register_listener(name, callable = nil, &block) ⇒ Object

:call-seq:

doc.register_listener(name, callable)             -> callable
doc.register_listener(name) {|*args| block}       -> block

Registers the given listener for the message name.

If callable is provided, it needs to be an Object responding to #call. Otherwise the block has to be provided. The arguments that are provided to the #call method depend on the message.

See: dispatch_message



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# File 'lib/hexapdf/document.rb', line 436

def register_listener(name, callable = nil, &block)
  callable ||= block
  (@listeners[name] ||= []) << callable
  callable
end

#security_handler ⇒ Object

Returns the security handler that is used for decrypting or encrypting the document, or nil if none is set.

  • If the document was created by reading an existing file and the document was automatically decrypted, then this method returns the handler for decrypting.

  • Once the #encrypt method is called, the specified security handler for encrypting is returned.



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# File 'lib/hexapdf/document.rb', line 632

def security_handler
  @security_handler
end

#sign(file_or_io, handler: :default, signature: nil, write_options: {}, **handler_options) ⇒ Object

Signs the document and writes it to the given file or IO object.

For details on the arguments file_or_io, signature and write_options see DigitalSignature::Signatures#add.

The signing handler to be used is determined by the handler argument together with the rest of the keyword arguments (see DigitalSignature::Signatures#signing_handler for details).

If not changed, the default signing handler is DigitalSignature::Signing::DefaultHandler.

Note: Once signing is done the document cannot be changed anymore since it was written during the signing process. If a document needs to be signed multiple times, it needs to be loaded again afterwards.



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# File 'lib/hexapdf/document.rb', line 660

def sign(file_or_io, handler: :default, signature: nil, write_options: {}, **handler_options)
  handler = signatures.signing_handler(name: handler, **handler_options)
  signatures.add(file_or_io, handler, signature: signature, write_options: write_options)
end

#signatures ⇒ Object

Returns a DigitalSignature::Signatures object that allows working with the digital signatures of this document.



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# File 'lib/hexapdf/document.rb', line 643

def signatures
  @signatures ||= DigitalSignature::Signatures.new(self)
end

#signed? ⇒ Boolean

Returns true if the document is signed, i.e. contains digital signatures.

Returns:

  • (Boolean) 


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# File 'lib/hexapdf/document.rb', line 637

def signed?
  acro_form&.signature_flag?(:signatures_exist)
end

#task(name, **opts, &block) ⇒ Object

Executes the given task and returns its result.

Tasks provide an extensible way for performing operations on a PDF document without cluttering the Document interface.

See: Task



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# File 'lib/hexapdf/document.rb', line 554

def task(name, **opts, &block)
  task = config.constantize('task.map', name) do
    raise HexaPDF::Error, "No task named '#{name}' is available"
  end
  task.call(self, **opts, &block)
end

#trailer ⇒ Object

Returns the trailer dictionary for the document.

See: Type::Trailer



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# File 'lib/hexapdf/document.rb', line 564

def trailer
  @revisions.current.trailer
end

#unwrap(object, seen = {}) ⇒ Object

:call-seq:

document.unwrap(obj)   -> unwrapped_obj

Recursively unwraps the object to get native Ruby objects (i.e. Hash, Array, Integer, … instead of HexaPDF::Reference and HexaPDF::Object).



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# File 'lib/hexapdf/document.rb', line 385

def unwrap(object, seen = {})
  object = deref(object)
  object = object.data if object.kind_of?(HexaPDF::Object)
  if seen.key?(object)
    raise HexaPDF::Error, "Can't unwrap a recursive structure"
  end

  case object
  when Hash
    seen[object] = true
    object.transform_values {|value| unwrap(value, seen.dup) }
  when Array
    seen[object] = true
    object.map {|inner_o| unwrap(inner_o, seen.dup) }
  when HexaPDF::PDFData
    seen[object] = true
    unwrap(object.value, seen.dup)
  else
    object
  end
end

#validate(auto_correct: true, only_loaded: false, &block) ⇒ Object

Validates all current objects, or, if only_loaded is true, only loaded objects, with optional auto-correction, and returns true if everything is fine.

If a block is given, it is called on validation problems.

See Object#validate for more information.



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# File 'lib/hexapdf/document.rb', line 671

def validate(auto_correct: true, only_loaded: false, &block) #:yield: msg, correctable, object
  result = trailer.validate(auto_correct: auto_correct, &block)
  each(only_loaded: only_loaded) do |obj|
    result &&= obj.validate(auto_correct: auto_correct, &block)
  end
  result
end

#version ⇒ Object

Returns the PDF document’s version as string (e.g. ‘1.4’).

This method takes the file header version and the catalog’s /Version key into account. If a version has been set manually and the catalog’s /Version key refers to a later version, the later version is used.

See: PDF2.0 s7.2.2



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# File 'lib/hexapdf/document.rb', line 582

def version
  catalog_version = (catalog[:Version] || '1.0').to_s
  (@version < catalog_version ? catalog_version : @version)
end

#version=(value) ⇒ Object

Sets the version of the PDF document.

The argument value must be a string in the format ‘M.N’ where M is the major version and N the minor version (e.g. ‘1.4’ or ‘2.0’).

Raises:

  • (ArgumentError) 


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# File 'lib/hexapdf/document.rb', line 591

def version=(value)
  raise ArgumentError, "PDF version must follow format M.N" unless value.to_s.match?(/\A\d\.\d\z/)
  @version = value.to_s
end

#wrap(obj, type: nil, subtype: nil, oid: nil, gen: nil, stream: nil) ⇒ Object

Wraps the given object inside a HexaPDF::Object (sub)class which allows one to use convenience functions to work with the object.

The obj argument can also be a HexaPDF::Object object so that it can be re-wrapped if necessary.

The class of the returned object is always a subclass of HexaPDF::Object (or of HexaPDF::Stream if stream is given). Which subclass is used, depends on the values of the type and subtype options as well as on the ‘object.type_map’ and ‘object.subtype_map’ global configuration options:

  • First type is used to try to determine the class. If it is not provided and if obj is a hash with a :Type field, the value of this field is used instead. If the resulting object is already a Class object, it is used, otherwise the type is looked up in ‘object.type_map’.

  • If subtype is provided or can be determined because obj is a hash with a :Subtype or :S field, the type and subtype together are used to look up a special subtype class in ‘object.subtype_map’.

    Additionally, if there is no type but a subtype, all required fields of the subtype class need to have values; otherwise the subtype class is not used. This is done to better prevent invalid mappings when only partial knowledge (:Type key is missing) is available.

  • If there is no valid class after the above steps, HexaPDF::Stream is used if a stream is given, HexaPDF::Dictionary if the given object is a hash, HexaPDF::PDFArray if it is an array or else HexaPDF::Object.

Options:

:type

(Symbol or Class) The type of a PDF object that should be used for wrapping. This could be, for example, :Pages. If a class object is provided, it is used directly instead of determining the class through the type detection system.

:subtype

(Symbol) The subtype of a PDF object which further qualifies a type. For example, image objects in PDF have a type of :XObject and a subtype of :Image.

:oid

(Integer) The object number that should be set on the wrapped object. Defaults to 0 or the value of the given object’s object number.

:gen

(Integer) The generation number that should be set on the wrapped object. Defaults to 0 or the value of the given object’s generation number.

:stream

(String or StreamData) The stream object which should be set on the wrapped object.



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# File 'lib/hexapdf/document.rb', line 329

def wrap(obj, type: nil, subtype: nil, oid: nil, gen: nil, stream: nil)
  data = if obj.kind_of?(HexaPDF::Object)
           obj.data
         else
           HexaPDF::PDFData.new(obj)
         end
  data.oid = oid if oid
  data.gen = gen if gen
  data.stream = stream if stream

  if type.kind_of?(Class)
    klass = type
    type = (klass <= HexaPDF::Dictionary ? klass.type : nil)
  else
    type ||= deref(data.value[:Type]) if data.value.kind_of?(Hash)
    if type
      klass = GlobalConfiguration.constantize('object.type_map', type) { nil }
      if (type == :ObjStm || type == :XRef) &&
          klass.each_field.any? {|name, field| field.required? && !data.value.key?(name) }
        data.value.delete(:Type)
        klass = nil
      end
    end
  end

  if data.value.kind_of?(Hash)
    subtype ||= deref(data.value[:Subtype]) || deref(data.value[:S])
  end
  if subtype
    sub_klass = GlobalConfiguration.constantize('object.subtype_map', type, subtype) { klass }
    if type ||
        sub_klass&.each_field&.none? do |name, field|
          field.required? && !data.value.key?(name) && name != :Type
        end
      klass = sub_klass
    end
  end

  klass ||= if data.stream
              HexaPDF::Stream
            elsif data.value.kind_of?(Hash)
              HexaPDF::Dictionary
            elsif data.value.kind_of?(Array)
              HexaPDF::PDFArray
            else
              HexaPDF::Object
            end

  klass.new(data, document: self)
end

#write(file_or_io, incremental: false, validate: true, update_fields: true, optimize: false) ⇒ Object

:call-seq:

doc.write(filename, incremental: false, validate: true, update_fields: true, optimize: false)
doc.write(io, incremental: false, validate: true, update_fields: true, optimize: false)

Writes the document to the given file (in case io is a String) or IO stream.

Before the document is written, it is validated using #validate and an error is raised if the document is not valid. However, this step can be skipped if needed.

Options:

incremental

Use the incremental writing mode which just adds a new revision to an existing document. This is needed, for example, when modifying a signed PDF and the original signature should stay valid.

See: PDF2.0 s7.5.6

validate

Validates the document and raises an error if an uncorrectable problem is found.

update_fields

Updates the /ID field in the trailer dictionary as well as the /ModDate field in the trailer’s /Info dictionary so that it is clear that the document has been updated.

optimize

Optimize the file size by using object and cross-reference streams. This will raise the PDF version to at least 1.5.



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# File 'lib/hexapdf/document.rb', line 707

def write(file_or_io, incremental: false, validate: true, update_fields: true, optimize: false)
  dispatch_message(:complete_objects)

  if update_fields
    trailer.update_id
    trailer.info[:ModDate] = Time.now
  end

  if validate
    self.validate(auto_correct: true) do |msg, correctable, obj|
      next if correctable
      raise HexaPDF::Error, "Validation error for (#{obj.oid},#{obj.gen}): #{msg}"
    end
  end

  if optimize
    task(:optimize, object_streams: :generate)
    self.version = '1.5' if version < '1.5'
  end

  dispatch_message(:before_write)

  if file_or_io.kind_of?(String)
    File.open(file_or_io, 'w+') {|file| Writer.write(self, file, incremental: incremental) }
  else
    Writer.write(self, file_or_io, incremental: incremental)
  end
end