Class: Prawn::Core::ObjectStore

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/prawn/core/object_store.rb

Overview

:nodoc:

Constant Summary collapse

BASE_OBJECTS = 
%w[info pages root]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ ObjectStore

Returns a new instance of ObjectStore.



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# File 'lib/prawn/core/object_store.rb', line 21

def initialize(opts = {})
  @objects = {}
  @identifiers = []

  load_file(opts[:template]) if opts[:template]

  @info  ||= ref(opts[:info] || {}).identifier
  @root  ||= ref(:Type => :Catalog).identifier
  if pages.nil?
    root.data[:Pages] = ref(:Type => :Pages, :Count => 0, :Kids => [])
  end
end

Instance Attribute Details

#min_version ⇒ Object (readonly)

Returns the value of attribute min_version.



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# File 'lib/prawn/core/object_store.rb', line 17

def min_version
  @min_version
end

Instance Method Details

#[](id) ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 78

def [](id)
  @objects[id]
end

#compact ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 87

def compact
  # Clear live markers
  each { |o| o.live = false }

  # Recursively mark reachable objects live, starting from the roots
  # (the only objects referenced in the trailer)
  root.mark_live
  info.mark_live

  # Renumber live objects to eliminate gaps (shrink the xref table)
  if @objects.any?{ |_, o| !o.live }
    new_id = 1
    new_objects = {}
    new_identifiers = []

    each do |obj|
      if obj.live
        obj.identifier = new_id
        new_objects[new_id] = obj
        new_identifiers << new_id
        new_id += 1
      end
    end

    @objects = new_objects
    @identifiers = new_identifiers
  end
end

#each ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 72

def each
  @identifiers.each do |id|
    yield @objects[id]
  end
end

#import_page(filename, page_num) ⇒ Object

imports all objects required to render a page from another PDF. The objects are added to the current object store, but NOT linked anywhere.

The object ID of the root Page object is returned, it’s up to the calling code to link that into the document structure somewhere. If this isn’t done the imported objects will just be removed when the store is compacted.

Imports nothing and returns nil if the requested page number doesn’t exist. page_num is 1 indexed, so 1 indicates the first page.



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# File 'lib/prawn/core/object_store.rb', line 144

def import_page(filename, page_num)
  @loaded_objects = {}
  unless File.file?(filename)
    raise ArgumentError, "#{filename} does not exist"
  end

  hash = PDF::Reader::ObjectHash.new(filename)
  ref  = hash.page_references[page_num - 1]

  ref.nil? ? nil : load_object_graph(hash, ref).identifier

rescue PDF::Reader::MalformedPDFError, PDF::Reader::InvalidObjectError
  msg = "Error reading template file. If you are sure it's a valid PDF, it may be a bug."
  raise Prawn::Errors::TemplateError, msg
rescue PDF::Reader::UnsupportedFeatureError
  msg = "Template file contains unsupported PDF features"
  raise Prawn::Errors::TemplateError, msg
end

#info ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 38

def info
  @objects[@info]
end

#object_id_for_page(k) ⇒ Object

returns the object ID for a particular page in the document. Pages are indexed starting at 1 (not 0!).

object_id_for_page(1)
=> 5
object_id_for_page(10)
=> 87
object_id_for_page(-11)
=> 17



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# File 'lib/prawn/core/object_store.rb', line 126

def object_id_for_page(k)
  k -= 1 if k > 0
  flat_page_ids = get_page_objects(pages).flatten
  flat_page_ids[k]
end

#page_count ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 50

def page_count
  pages.data[:Count]
end

#pages ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 46

def pages
  root.data[:Pages]
end

#push(*args, &block) ⇒ Object Also known as: <<

Adds the given reference to the store and returns the reference object. If the object provided is not a Prawn::Core::Reference, one is created from the arguments provided.



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# File 'lib/prawn/core/object_store.rb', line 58

def push(*args, &block)
  reference = if args.first.is_a?(Prawn::Core::Reference)
    args.first
  else
    Prawn::Core::Reference.new(*args, &block)
  end

  @objects[reference.identifier] = reference
  @identifiers << reference.identifier
  reference
end

#ref(data, &block) ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 34

def ref(data, &block)
  push(size + 1, data, &block)
end

#root ⇒ Object 



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# File 'lib/prawn/core/object_store.rb', line 42

def root
  @objects[@root]
end

#size ⇒ Object Also known as: length 



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# File 'lib/prawn/core/object_store.rb', line 82

def size
  @identifiers.size
end