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@adrienpoly
Forked from fidothe/pdfx.rb
Created January 25, 2022 05:43
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Worked example for creating a PDF/X-1a:2003 document with Prawn
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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