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.
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
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
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
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
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
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
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
# File lib/prawn/document/internals.rb, line 89 def finalize_all_page_contents (1..page_count).each do |i| go_to_page i repeaters.each { |r| r.run(i) } restore_graphics_state page.content.compress_stream if compression_enabled? page.content.data[:Length] = page.content.stream.size end end
raise the PDF version of the file we're going to generate. A private method, designed for internal use when the user adds a feature to their document that requires a particular version.
# File lib/prawn/document/internals.rb, line 103 def min_version(min) @version = min if min > @version end
Write out the PDF Body, as per spec 3.4.2
# File lib/prawn/document/internals.rb, line 121 def render_body(output) @store.compact if @optimize_objects @store.each do |ref| ref.offset = output.size output << ref.object end end
Write out the PDF Header, as per spec 3.4.1
# File lib/prawn/document/internals.rb, line 109 def render_header(output) @before_render_callbacks.each{ |c| c.call(self) } # pdf version output << "%PDF-#{@version}\n" # 4 binary chars, as recommended by the spec output << "%\xFF\xFF\xFF\xFF\n" end
Write out the PDF Trailer, as per spec 3.4.4
# File lib/prawn/document/internals.rb, line 144 def render_trailer(output) trailer_hash = {:Size => @store.size + 1, :Root => @store.root, :Info => @store.info} trailer_hash.merge!(@trailer) if @trailer output << "trailer\n" output << Prawn::PdfObject(trailer_hash) << "\n" output << "startxref\n" output << @xref_offset << "\n" output << "%%EOF" << "\n" end
Write out the PDF Cross Reference Table, as per spec 3.4.3
# File lib/prawn/document/internals.rb, line 131 def render_xref(output) @xref_offset = output.size output << "xref\n" output << "0 #{@store.size + 1}\n" output << "0000000000 65535 f \n" @store.each do |ref| output.printf("%010d", ref.offset) output << " 00000 n \n" end end