PDF imposition in Ruby

#---------------------------------------------------------------------------------------
# Copyright (c) 2001-2022 by PDFTron Systems Inc. All Rights Reserved.
# Consult LICENSE.txt regarding license information.
#---------------------------------------------------------------------------------------

require '../../../PDFNetC/Lib/PDFNetRuby'
include PDFNetRuby
require '../../LicenseKey/RUBY/LicenseKey'

$stdout.sync = true

# Relative path to the folder containing the test files.
input_path = "../../TestFiles/newsletter.pdf"
output_path = "../../TestFiles/Output/newsletter_booklet.pdf"

#-----------------------------------------------------------------------------------
# The sample illustrates how multiple pages can be combined/imposed 
# using PDFNet. Page imposition can be used to arrange/order pages 
# prior to printing or to assemble a 'master' page from several 'source' 
# pages. Using PDFNet API it is possible to write applications that can 
# re-order the pages such that they will display in the correct order 
# when the hard copy pages are compiled and folded correctly. 
#-----------------------------------------------------------------------------------

	PDFNet.Initialize(PDFTronLicense.Key)
	
	puts "-------------------------------------------------"
	puts "Opening the input pdf..."
	
	in_doc = PDFDoc.new(input_path)
	in_doc.InitSecurityHandler
	
	# Create a list of pages to import from one PDF document to another
	import_pages = VectorPage.new
	itr = in_doc.GetPageIterator
	while itr.HasNext do
		import_pages << (itr.Current)
		itr.Next
	end

	new_doc = PDFDoc.new
	imported_pages = new_doc.ImportPages(import_pages)

	# Paper dimension for A3 format in points. Because one inch has 
	# 72 points, 11.69 inch 72 = 841.69 points
	media_box = Rect.new(0, 0, 1190.88, 841.69)
	mid_point = media_box.Width/2

	builder = ElementBuilder.new
	writer = ElementWriter.new

	i = 0	
	while i < imported_pages.size do
		# Create a blank new A3 page and place on it two pages from the input document.
		new_page = new_doc.PageCreate(media_box)
		writer.Begin(new_page)
		
		# Place the first page
		src_page = imported_pages[i]
		
		element = builder.CreateForm(imported_pages[i])
		sc_x = mid_point / src_page.GetPageWidth
		sc_y = media_box.Height / src_page.GetPageHeight
		scale = sc_x < sc_y ? sc_x : sc_y	# min(sc_x, sc_y)
		element.GetGState.SetTransform(scale, 0, 0, scale, 0, 0)
		writer.WritePlacedElement(element)
		
		# Place the second page
		i = i + 1
		if i < imported_pages.size
			src_page = imported_pages[i]
			element = builder.CreateForm(src_page)
			sc_x = mid_point / src_page.GetPageWidth
			sc_y = media_box.Height / src_page.GetPageHeight
			scale = sc_x < sc_y ? sc_x : sc_y	# min(sc_x, sc_y)
			element.GetGState.SetTransform(scale, 0, 0, scale, mid_point, 0)
			writer.WritePlacedElement(element)
		end
			
		writer.End
		new_doc.PagePushBack(new_page)
		i = i + 1
	end
		
	new_doc.Save(output_path, SDFDoc::E_linearized)
	PDFNet.Terminate
	puts "Done. Result saved in newsletter_booklet.pdf..."