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Ruby PDF editor (programmatic)

Sample Ruby code for using PDFTron SDK to programmatically edit an existing PDF document's page display list and the graphics state attributes on existing elements. In particular, this sample strips all images from the page and changes the text color to blue. You can also build a GUI with interactive PDF editor widgets. Some of PDFTron SDK's other functions for programmatically editing PDFs include the Cos/SDF low-level API, page manipulation, and more. Learn more about our PDF Editing & Manipulation Library.

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#---------------------------------------------------------------------------------------
# Copyright (c) 2001-2019 by PDFTron Systems Inc. All Rights Reserved.
# Consult LICENSE.txt regarding license information.
#---------------------------------------------------------------------------------------

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

$stdout.sync = true

#---------------------------------------------------------------------------------------
# The sample code shows how to edit the page display list and how to modify graphics state 
# attributes on existing Elements. In particular the sample program strips all images from 
# the page and changes text color to blue. 
#---------------------------------------------------------------------------------------

def ProcessElements(reader, writer, map)
	element = reader.Next()	 # Read page contents
	while !element.nil? do
		type = element.GetType()
		case type
		when Element::E_image
		# remove all images by skipping them
		when Element::E_inline_image	
			# remove all images by skipping them
		when Element::E_text	# Process text strings...
			# Set all text to blue color.
			gs = element.GetGState()
			gs.SetFillColorSpace(ColorSpace.CreateDeviceRGB())
			cp = ColorPt.new(0, 0, 1)
			gs.SetFillColor(cp)
			writer.WriteElement(element)
		when Element::E_form	# Recursively process form XObjects
			o = element.GetXObject()
			map[o.GetObjNum()] = o
			writer.WriteElement(element)
		else
			writer.WriteElement(element)
		end
		element = reader.Next()
	end
end

	PDFNet.Initialize()
	
	# Relative path to the folder containing the test files.
	input_path = "../../TestFiles/"
	output_path = "../../TestFiles/Output/"
	input_filename = "newsletter.pdf"
	output_filename = "newsletter_edited.pdf"
	
	puts "-------------------------------------------------"
	
	# Open the test file
	puts "Opening the input file..."
	doc = PDFDoc.new(input_path + input_filename)
	doc.InitSecurityHandler()
	
	writer = ElementWriter.new()
	reader = ElementReader.new()
	
	itr = doc.GetPageIterator()
	
	while itr.HasNext() do
		page = itr.Current()
		reader.Begin(page)
		writer.Begin(page, ElementWriter::E_replacement, false)
		map1 = {}
		ProcessElements(reader, writer, map1)
		writer.End()
		reader.End()
		
		map2 = {}
		while (not(map1.empty? and map2.empty?)) do
			map1.each do |k, v|
				obj = v
				writer.Begin(obj)
				reader.Begin(obj, page.GetResourceDict())
				ProcessElements(reader, writer, map2)
				reader.End()
				writer.End()

				map1.delete(k)
			end
			if (map1.empty? and not map2.empty?)
				map1.update(map2)
				map2.clear
			end
		end
		itr.Next()
	end
		
	doc.Save(output_path + output_filename, SDFDoc::E_remove_unused)
	doc.Close()
	puts "Done. Result saved in " + output_filename + "..."
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