Some test text!

menu

Undo / redo edits to a PDF file using PHP

More languages

chevron_right
More languages
Java (Android)
C++
C#
C# (.NET Core)
Java
Kotlin
Obj-C
PHP
Python
Ruby
C# (UWP)
VB
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 PHP 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 PHP PDF Library.

Get StartedSamplesDownload

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

<?php
//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2020 by PDFTron Systems Inc. All Rights Reserved.
// Consult LICENSE.txt regarding license information.
//---------------------------------------------------------------------------------------
include("../../../PDFNetC/Lib/PDFNetPHP.php");

// Relative path to the folder containing the test files.
$input_path = getcwd()."/../../TestFiles/";
$output_path = $input_path."Output/";

//---------------------------------------------------------------------------------------
// The following sample illustrates how to use the UndoRedo API.
//---------------------------------------------------------------------------------------
	
	// 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();
	PDFNet::GetSystemFontList();    // Wait for fonts to be loaded if they haven't already. This is done because PHP can run into errors when shutting down if font loading is still in progress.
	
	// Open the PDF document.
	$doc = new PDFDoc($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();
	
	$builder = new ElementBuilder();	// Used to build new Element objects
	$writer = new ElementWriter();		// Used to write Elements to the page
	
	$page = $doc->PageCreate();		// Start a new page
	$writer->Begin($page);			// Begin writing to this page
	
	// ----------------------------------------------------------
	// Add JPEG image to the output file
	$img = Image::Create($doc->GetSDFDoc(), $input_path."peppers.jpg");
	
	$element = $builder->CreateImage($img, new Matrix2D(200.0,0.0,0.0,250.0,50.0,500.0));
	$writer->WritePlacedElement($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))
	{
		echo(nl2br("snap1 previous state equals snap0_state; previous state is correct\n"));
	}

	$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))
		{
			echo(nl2br("undo_snap_state equals snap0_state; undo was successful\n"));
		}
		
		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))
			{
				echo(nl2br("redo_snap previous state equals undo_snap_state; previous state is correct\n"));
			}
			
			$redo_snap_state = $redo_snap->CurrentState();
			
			if ($redo_snap_state->Equals($snap1_state))
			{
				echo(nl2br("Snap1 and redo_snap are equal; redo was successful\n"));
			}
		}
		else
		{
			echo(nl2br("Problem encountered - cannot redo.\n"));
		}
	}
	else
	{
		echo(nl2br("Problem encountered - cannot undo.\n"));
	}

?>
close

Free Trial

Get unlimited trial usage of PDFTron SDK to bring accurate, reliable, and fast document processing capabilities to any application or workflow.

Select a platform to get started with your free trial.

Unlimited usage. No email address required.

Join our live demo to learn about use cases & capabilities for WebViewer

Learn more
close