module Prawn::Images

Public Instance Methods

build_image_object(file) click to toggle source

Builds an info object (Prawn::Images::*) and a PDF reference representing the given image. Return a pair: [pdf_obj, info].

@private

# File lib/prawn/images.rb, line 81
def build_image_object(file)
  io = verify_and_open_image(file)
  image_content = io.read
  image_sha1 = Digest::SHA1.hexdigest(image_content)

  # if this image has already been embedded, just reuse it
  if image_registry[image_sha1]
    info = image_registry[image_sha1][:info]
    image_obj = image_registry[image_sha1][:obj]
  else
    # Build the image object
    info = Prawn.image_handler.find(image_content).new(image_content)

    # Bump PDF version if the image requires it
    if info.respond_to?(:min_pdf_version)
      renderer.min_version(info.min_pdf_version)
    end

    # Add the image to the PDF and register it in case we see it again.
    image_obj = info.build_pdf_object(self)
    image_registry[image_sha1] = { obj: image_obj, info: info }
  end

  [image_obj, info]
end
embed_image(pdf_obj, info, options) click to toggle source

Given a PDF image resource pdf_obj that has been added to the page's resources and an info object (the pair returned from build_image_object), embed the image according to the options given.

@private

# File lib/prawn/images.rb, line 113
def embed_image(pdf_obj, info, options)
  # find where the image will be placed and how big it will be
  w, h = info.calc_image_dimensions(options)

  if options[:at]
    x, y = map_to_absolute(options[:at])
  else
    x, y = image_position(w, h, options)
    move_text_position h
  end

  # add a reference to the image object to the current page
  # resource list and give it a label
  label = "I#{next_image_id}"
  state.page.xobjects[label] = pdf_obj

  cm_params = PDF::Core.real_params([w, 0, 0, h, x, y - h])
  renderer.add_content("\nq\n#{cm_params} cm\n/#{label} Do\nQ")
end
image(file, options = {}) click to toggle source

Add the image at filename to the current page. Currently only JPG and PNG files are supported. (Note that processing PNG images with alpha channels can be processor and memory intensive.)

Arguments:

file

path to file or an object that responds to read and

#rewind

Options:

:at

an array [x,y] with the location of the top left corner of

the image.
:position

One of (:left, :center, :right) or an x-offset

:vposition

One of (:top, :center, :bottom) or an y-offset

:height

the height of the image [actual height of the image]

:width

the width of the image [actual width of the image]

:scale

scale the dimensions of the image proportionally

:fit

scale the dimensions of the image proportionally to fit

inside [width,height]

Prawn::Document.generate("image2.pdf", :page_layout => :landscape) do
  pigs = "#{Prawn::DATADIR}/images/pigs.jpg"
  image pigs, :at => [50,450], :width => 450

  dice = "#{Prawn::DATADIR}/images/dice.png"
  image dice, :at => [50, 450], :scale => 0.75
end

If only one of :width / :height are provided, the image will be scaled proportionally. When both are provided, the image will be stretched to fit the dimensions without maintaining the aspect ratio.

If :at is provided, the image will be place in the current page but the text position will not be changed.

If instead of an explicit filename, an object with a read method is passed as file, you can embed images from IO objects and things that act like them (including Tempfiles and open-uri objects).

require "open-uri"

Prawn::Document.generate("remote_images.pdf") do
  image open("http://prawnpdf.org/media/prawn_logo.png")
end

This method returns an image info object which can be used to check the dimensions of an image object if needed. (See also: Prawn::Images::PNG , Prawn::Images::JPG)

# File lib/prawn/images.rb, line 65
def image(file, options = {})
  Prawn.verify_options [
    :at, :position, :vposition, :height,
    :width, :scale, :fit
  ], options

  pdf_obj, info = build_image_object(file)
  embed_image(pdf_obj, info, options)

  info
end

Private Instance Methods

determine_y_with_page_flow(h) click to toggle source
# File lib/prawn/images.rb, line 184
def determine_y_with_page_flow(h)
  if overruns_page?(h)
    bounds.move_past_bottom
  end
  y
end
image_position(w, h, options) click to toggle source
# File lib/prawn/images.rb, line 154
def image_position(w, h, options)
  options[:position] ||= :left

  y = case options[:vposition]
      when :top
        bounds.absolute_top
      when :center
        bounds.absolute_top - (bounds.height - h) / 2.0
      when :bottom
        bounds.absolute_bottom + h
      when Numeric
        bounds.absolute_top - options[:vposition]
      else
        determine_y_with_page_flow(h)
      end

  x = case options[:position]
      when :left
        bounds.left_side
      when :center
        bounds.left_side + (bounds.width - w) / 2.0
      when :right
        bounds.right_side - w
      when Numeric
        options[:position] + bounds.left_side
      end

  [x, y]
end
image_registry() click to toggle source
# File lib/prawn/images.rb, line 195
def image_registry
  @image_registry ||= {}
end
next_image_id() click to toggle source
# File lib/prawn/images.rb, line 199
def next_image_id
  @image_counter ||= 0
  @image_counter += 1
end
overruns_page?(h) click to toggle source
# File lib/prawn/images.rb, line 191
def overruns_page?(h)
  (y - h) < reference_bounds.absolute_bottom
end
verify_and_open_image(io_or_path) click to toggle source
# File lib/prawn/images.rb, line 135
def verify_and_open_image(io_or_path)
  # File or IO
  if io_or_path.respond_to?(:rewind)
    io = io_or_path
    # Rewind if the object we're passed is an IO, so that multiple embeds of
    # the same IO object will work
    io.rewind
    # read the file as binary so the size is calculated correctly
    # guard binmode because some objects acting io-like don't implement it
    io.binmode if io.respond_to?(:binmode)
    return io
  end
  # String or Pathname
  io_or_path = Pathname.new(io_or_path)
  raise ArgumentError, "#{io_or_path} not found" unless io_or_path.file?
  io = io_or_path.open('rb')
  io
end