module Prawn::Stamp

The Prawn::Stamp module is used to create content that will be included multiple times in a document. Using a stamp has three advantages over creating content anew each time it is placed on the page:

i.   faster document creation
ii.  smaller final document
iii. faster display on subsequent displays of the repeated
element because the viewer application can cache the rendered
results

Example:

pdf.create_stamp("my_stamp") {
  pdf.fill_circle_at([10, 15], :radius => 5)
  pdf.draw_text("hello world", :at => [20, 10])
}
pdf.stamp("my_stamp")

Public Instance Methods

create_stamp(name, &block) click to toggle source

Creates a re-usable stamp named name

raises Prawn::Errors::NameTaken if a stamp already exists in this document with this name raises Prawn::Errors::InvalidName if name.empty?

Example:

pdf.create_stamp("my_stamp") {
  pdf.fill_circle_at([10, 15], :radius => 5)
  pdf.draw_text("hello world", :at => [20, 10])
}
# File lib/prawn/stamp.rb, line 78
def create_stamp(name, &block)
  dictionary = create_stamp_dictionary(name)

  page.stamp_stream(dictionary, &block)
end
stamp(name) click to toggle source

Renders the stamp named name to the page raises Prawn::Errors::InvalidName if name.empty? raises Prawn::Errors::UndefinedObjectName if no stamp has been created with this name

Example:

pdf.create_stamp("my_stamp") {
  pdf.fill_circle_at([10, 15], :radius => 5)
  pdf.text("hello world", :at => [20, 10])
}
pdf.stamp("my_stamp")
# File lib/prawn/stamp.rb, line 43
def stamp(name)
  dictionary_name, dictionary = stamp_dictionary(name)
  add_content "/#{dictionary_name} Do"
  page.xobjects.merge!(dictionary_name => dictionary)
end
stamp_at(name, point) click to toggle source

Renders the stamp named name at a position offset from the initial coords at which the elements of the stamp was created

Example:

pdf.create_stamp("circle") do
  pdf.fill_circle_at([0, 0], :radius => 25)
end
# draws a circle at 100, 100
pdf.stamp_at("circle", [100, 100])

See stamp() for exceptions that might be raised

# File lib/prawn/stamp.rb, line 62
def stamp_at(name, point)
  translate(point[0], point[1]) { stamp(name) }
end

Private Instance Methods

create_stamp_dictionary(name) click to toggle source
# File lib/prawn/stamp.rb, line 107
def create_stamp_dictionary(name)
  raise Prawn::Errors::InvalidName if name.empty?
  raise Prawn::Errors::NameTaken unless stamp_dictionary_registry[name].nil?
  # BBox origin is the lower left margin of the page, so we need
  # it to be the full dimension of the page, or else things that
  # should appear near the top or right margin are invisible
  dictionary = ref!(:Type    => :XObject,
                    :Subtype => :Form,
                    :BBox    => [0, 0,
                                 page.dimensions[2], page.dimensions[3]])

  dictionary_name = "Stamp#{next_stamp_dictionary_id}"

  stamp_dictionary_registry[name] = {
                                  :stamp_dictionary_name => dictionary_name,
                                  :stamp_dictionary      => dictionary
                                     }
  dictionary
end
next_stamp_dictionary_id() click to toggle source
# File lib/prawn/stamp.rb, line 90
def next_stamp_dictionary_id
  stamp_dictionary_registry.length + 1
end
stamp_dictionary(name) click to toggle source
# File lib/prawn/stamp.rb, line 94
def stamp_dictionary(name)
  raise Prawn::Errors::InvalidName if name.empty?
  if stamp_dictionary_registry[name].nil?
    raise Prawn::Errors::UndefinedObjectName
  end

  dict = stamp_dictionary_registry[name]

  dictionary_name = dict[:stamp_dictionary_name]
  dictionary = dict[:stamp_dictionary]
  [dictionary_name, dictionary]
end
stamp_dictionary_registry() click to toggle source
# File lib/prawn/stamp.rb, line 86
def stamp_dictionary_registry
  @stamp_dictionary_registry ||= {}
end