Some test text!

Undo / redo edits to a PDF file using Python

More languages

Java (Android)

C++

C# (.NET Core)

Java

Kotlin

Obj-C

JS (Node.js)

PHP

Python

Ruby

C# (UWP)

C# (Xamarin)

The PDFTron SDK has a low-level facility for undo and redo operations. It is a API that applies to any edits made to a particular document (not just annotations). This sample Python code shows how to use PDFTron SDK to walk back and forth on a fully general, bit-exact list of document states. Saving changes in a mode that is not 'incremental' will wipe out the undo-redo state list; the API will not be able to access old snapshots anymore. See the undoing and redoing guide for more information. Learn more about our Python PDF Library.

Get Started Samples Download

To run this sample, get started with a free trial of Apryse SDK.

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

import site
site.addsitedir("../../../PDFNetC/Lib")
import sys
from PDFNetPython import *

sys.path.append("../../LicenseKey/PYTHON")
from LicenseKey import *

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

#---------------------------------------------------------------------------------------
# The following sample illustrates how to use the UndoRedo API.
#---------------------------------------------------------------------------------------

def main():
	# The first step in every application using PDFNet is to initialize the 
	# library and set the path to common PDF resources. The library is usually 
	# initialized only once, but calling Initialize() multiple times is also fine.
	PDFNet.Initialize(LicenseKey)
	
	# Open the PDF document.
	doc = PDFDoc(input_path + "newsletter.pdf")

	undo_manager = doc.GetUndoManager()

	# Take a snapshot to which we can undo after making changes.
	snap0 = undo_manager.TakeSnapshot()

	snap0_state = snap0.CurrentState()
	
	# Start a new page
	page = doc.PageCreate()

	bld = ElementBuilder()			# Used to build new Element objects
	writer = ElementWriter()		# Used to write Elements to the page
	writer.Begin(page)				# Begin writing to this page

	# ----------------------------------------------------------
	# Add JPEG image to the file
	img = Image.Create(doc.GetSDFDoc(), input_path + "peppers.jpg")

	element = bld.CreateImage(img, Matrix2D(200, 0, 0, 250, 50, 500))
	writer.WritePlacedElement(element)

	# Finish writing to the page
	writer.End()
	doc.PagePushFront(page)

	# Take a snapshot after making changes, so that we can redo later (after undoing first).
	snap1 = undo_manager.TakeSnapshot()

	if snap1.PreviousState().Equals(snap0_state):
		print("snap1 previous state equals snap0_state; previous state is correct")
		
	snap1_state = snap1.CurrentState()

	doc.Save(output_path + "addimage.pdf", SDFDoc.e_incremental)

	if undo_manager.CanUndo():
		undo_snap = undo_manager.Undo()

		doc.Save(output_path + "addimage_undone.pdf", SDFDoc.e_incremental)

		undo_snap_state = undo_snap.CurrentState()

		if undo_snap_state.Equals(snap0_state):
			print("undo_snap_state equals snap0_state; undo was successful")
		
		if undo_manager.CanRedo():
			redo_snap = undo_manager.Redo()

			doc.Save(output_path + "addimage_redone.pdf", SDFDoc.e_incremental)

			if redo_snap.PreviousState().Equals(undo_snap_state):
				print("redo_snap previous state equals undo_snap_state; previous state is correct")
			
			redo_snap_state = redo_snap.CurrentState()
			
			if redo_snap_state.Equals(snap1_state):
				print("Snap1 and redo_snap are equal; redo was successful")
		else:
			print("Problem encountered - cannot redo.")
	else:
		print("Problem encountered - cannot undo.")
	PDFNet.Terminate()
	
if __name__ == '__main__':
    main()