module Prawn::Document::Internals

This module exposes a few low-level PDF features for those who want to extend Prawn’s core functionality. If you are not comfortable with low level PDF functionality as defined by Adobe’s specification, chances are you won’t need anything you find here.

Public Instance Methods

add_content(str) click to toggle source

Appends a raw string to the current page content.

# Raw line drawing example:           
x1,y1,x2,y2 = 100,500,300,550
pdf.add_content("%.3f %.3f m" % [ x1, y1 ])  # move 
pdf.add_content("%.3f %.3f l" % [ x2, y2 ])  # draw path
pdf.add_content("S") # stroke
# File lib/prawn/document/internals.rb, line 47
def add_content(str)
  page.content << str << "\n"
end
before_render(&block) click to toggle source

Defines a block to be called just before the document is rendered.

# File lib/prawn/document/internals.rb, line 67
def before_render(&block)
  @before_render_callbacks << block
end
names() click to toggle source

The Name dictionary (PDF spec 3.6.3) for this document. It is lazily initialized, so that documents that do not need a name dictionary do not incur the additional overhead.

# File lib/prawn/document/internals.rb, line 55
def names
  @store.root.data[:Names] ||= ref!(:Type => :Names)
end
names?() click to toggle source

Returns true if the Names dictionary is in use for this document.

# File lib/prawn/document/internals.rb, line 61
def names?
  @store.root.data[:Names]
end
on_page_create(&block) click to toggle source

Defines a block to be called just before a new page is started.

# File lib/prawn/document/internals.rb, line 79
def on_page_create(&block)
   if block_given?
      @on_page_create_callback = block
   else
      @on_page_create_callback = nil
   end
end
ref(data) click to toggle source

Creates a new Prawn::Reference and adds it to the Document’s object list. The data argument is anything that Prawn::PdfObject() can convert.

Returns the identifier which points to the reference in the ObjectStore

# File lib/prawn/document/internals.rb, line 23
def ref(data)
  ref!(data).identifier
end
ref!(data) click to toggle source

Like ref, but returns the actual reference instead of its identifier.

While you can use this to build up nested references within the object tree, it is recommended to persist only identifiers, and them provide helper methods to look up the actual references in the ObjectStore if needed. If you take this approach, Prawn::Document::Snapshot will probably work with your extension

# File lib/prawn/document/internals.rb, line 35
def ref!(data)
  @store.ref(data)
end