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Worked example for creating a PDF/X-1a:2003 document with Prawn
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require 'prawn' | |
require 'prawn/measurements' | |
# I have a small collection of links to the resources I used to figure all | |
# this out: http://pinboard.in/u:fidothe/t:pdfx | |
module PDFX | |
class PageBox | |
include Prawn::Measurements | |
attr_reader :bleed_mm | |
def initialize(width, height, bleed) | |
@width_mm = width | |
@height_mm = height | |
@bleed_mm = bleed | |
end | |
def trim_dimensions_mm | |
[@width_mm, @height_mm] | |
end | |
def bleed_dimensions_mm | |
trim_dimensions_mm.map { |d| d + 2*bleed_mm } | |
end | |
alias_method :media_dimensions_mm, :bleed_dimensions_mm | |
def bleed_dimensions | |
mm_bbox_to_pts(bleed_dimensions_mm) | |
end | |
alias_method :media_dimensions, :bleed_dimensions | |
def trim_box_mm | |
[bleed_mm, bleed_mm] + trim_dimensions_mm.map { |d| d + bleed_mm } | |
end | |
def bleed_box_mm | |
[0, 0] + bleed_dimensions_mm | |
end | |
alias_method :media_box_mm, :bleed_box_mm | |
def trim_box | |
mm_bbox_to_pts(trim_box_mm) | |
end | |
def bleed_box | |
mm_bbox_to_pts(bleed_box_mm) | |
end | |
alias_method :media_box, :bleed_box | |
private | |
def mm_bbox_to_pts(bbox) | |
bbox.map { |d| mm2pt(d).round(3) } | |
end | |
end | |
class ICCProfileInfo | |
attr_reader :registry_name, :output_condition_identifier, :info, :output_condition, :profile_bytes | |
def initialize(attrs = {}) | |
[:registry_name, :output_condition_identifier, | |
:info, :output_condition].each do |attr_name| | |
instance_variable_set(:"@#{attr_name}", attrs.fetch(attr_name)) | |
end | |
@profile_bytes = Pathname.new(attrs.fetch(:profile)).binread | |
end | |
end | |
# IIRC, I got these values by examining the metadata in an InDesign | |
# generated PDF/X document | |
# | |
# You can download the ICC files themselves from Adobe at | |
# http://www.adobe.com/support/downloads/iccprofiles/iccprofiles_win.html | |
FOGRA39 = ICCProfileInfo.new({ | |
registry_name: "http://www.color.org", | |
output_condition_identifier: "FOGRA39", | |
info: "Coated FOGRA39 (ISO 12647-2:2004)", | |
output_condition: "Offset commercial and specialty printing according to ISO 12647-2:2004 / Amd 1, paper type 1 or 2 (gloss or matte coated offset, 115 g/m2), screen frequency 60/cm.", | |
profile: 'CoatedFOGRA39.icc' | |
}) | |
class Document | |
PDFX_VERSION = 'PDF/X-1a:2003' | |
def self.generate(path, title) | |
doc = new(path) | |
yield(doc) | |
doc.render_file(path) | |
end | |
attr_reader :pdf, :title | |
def initialize(title) | |
@title = title | |
@pdf = Prawn::Document.new(skip_page_creation: true, info: info_keys) | |
add_pdfx_metadata! | |
end | |
def start_new_page(page_box, opts = {}) | |
pdf.start_new_page(opts.merge(size: page_box.media_dimensions)) | |
pdf.page.dictionary.data[:BleedBox] = page_box.bleed_box | |
pdf.page.dictionary.data[:TrimBox] = page_box.trim_box | |
end | |
def method_missing(name, *args) | |
pdf.send(name, *args) | |
end | |
private | |
def add_pdfx_metadata! | |
pdf.state.trailer = trailer_keys | |
add_output_intents! | |
end | |
def add_output_intents! | |
# The data here declares this a CMYK PDF/X ICC profile- 4 colours, | |
# with each having a value range of 0-1 | |
# Then we add and compress the bytes of the ICC profile itself | |
profile = pdf.ref!({N: 4, Range: [0, 1, 0, 1, 0, 1, 0, 1]}) | |
profile << FOGRA39.profile_bytes | |
profile.stream.compress! | |
intent = [{ | |
Type: :OutputIntent, | |
S: :GTS_PDFX, | |
RegistryName: PDF::Core::LiteralString.new(FOGRA39.registry_name), | |
OutputConditionIdentifier: PDF::Core::LiteralString.new(FOGRA39.output_condition_identifier), | |
Info: PDF::Core::LiteralString.new(FOGRA39.info), | |
OutputCondition: PDF::Core::LiteralString.new(FOGRA39.output_condition), | |
DestOutputProfile: profile | |
}] | |
pdf.state.store.root.data[:OutputIntents] = intent | |
end | |
def trailer_keys | |
id = SecureRandom.uuid | |
{ID: [id, id]} | |
end | |
def pdfx_keys(info_dict) | |
info_dict.merge({GTS_PDFXVersion: PDFX_VERSION, GTS_PDFXConformance: PDFX_VERSION}) | |
end | |
def trapped_key(info_dict) | |
info_dict.merge({Trapped: :False}) | |
end | |
def title_key(info_dict) | |
info_dict.merge({Title: title}) | |
end | |
def date_keys(info_dict) | |
time = Time.now | |
info_dict.merge({ModDate: time, CreationDate: time}) | |
end | |
def info_keys | |
date_keys(title_key(pdfx_keys(trapped_key({})))) | |
end | |
end | |
end | |
A4 = PDFX::PageBox.new(210, 297, 3) | |
PDFX::Document.generate('pdfx.pdf', 'My PDF/X document') do |pdf| | |
pdf.start_new_page(A4, margin: 0) | |
pdf.fill_color(100, 0, 0, 0) | |
pdf.text "HELLO PDF/X" | |
end |
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