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iText Xtra, part of iText a Free Java-PDF library
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/*
*
* This file is part of the iText (R) project.
Copyright (c) 1998-2022 iText Group NV
* Authors: Bruno Lowagie, Paulo Soares, et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License version 3
* as published by the Free Software Foundation with the addition of the
* following permission added to Section 15 as permitted in Section 7(a):
* FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
* ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
* OF THIRD PARTY RIGHTS
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Affero General Public License for more details.
* You should have received a copy of the GNU Affero General Public License
* along with this program; if not, see http://www.gnu.org/licenses or write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA, 02110-1301 USA, or download the license from the following URL:
* http://itextpdf.com/terms-of-use/
*
* The interactive user interfaces in modified source and object code versions
* of this program must display Appropriate Legal Notices, as required under
* Section 5 of the GNU Affero General Public License.
*
* In accordance with Section 7(b) of the GNU Affero General Public License,
* a covered work must retain the producer line in every PDF that is created
* or manipulated using iText.
*
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial activities involving the iText software without
* disclosing the source code of your own applications.
* These activities include: offering paid services to customers as an ASP,
* serving PDFs on the fly in a web application, shipping iText with a closed
* source product.
*
* For more information, please contact iText Software Corp. at this
* address: [email protected]
*/
package com.itextpdf.text.pdf.ocg;
import com.itextpdf.text.pdf.PRStream;
import com.itextpdf.text.pdf.PdfArray;
import com.itextpdf.text.pdf.PdfDictionary;
import com.itextpdf.text.pdf.PdfName;
import com.itextpdf.text.pdf.PdfObject;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfString;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* Class that knows how to remove OCG layers.
*/
public class OCGRemover {
/**
* Removes layers from a PDF document
* @param reader a PdfReader containing a PDF document
* @param layers a sequence of names of OCG layers
* @throws IOException
*/
public void removeLayers(PdfReader reader, String... layers) throws IOException {
int n = reader.getNumberOfPages();
for (int i = 1; i <= n; i++)
reader.setPageContent(i, reader.getPageContent(i));
Set ocgs = new HashSet();
for (int i = 0; i < layers.length; i++) {
ocgs.add(layers[i]);
}
OCGParser parser = new OCGParser(ocgs);
PdfDictionary page;
for (int i = 1; i <= n; i++) {
page = reader.getPageN(i);
parse(parser, page);
page.remove(PdfName.PIECEINFO);
removeAnnots(page, ocgs);
removeProperties(page, ocgs);
}
PdfDictionary root = reader.getCatalog();
PdfDictionary ocproperties = root.getAsDict(PdfName.OCPROPERTIES);
if (ocproperties != null) {
removeOCGsFromArray(ocproperties, PdfName.OCGS, ocgs);
PdfDictionary d = ocproperties.getAsDict(PdfName.D);
if (d != null) {
removeOCGsFromArray(d, PdfName.ON, ocgs);
removeOCGsFromArray(d, PdfName.OFF, ocgs);
removeOCGsFromArray(d, PdfName.LOCKED, ocgs);
removeOCGsFromArray(d, PdfName.RBGROUPS, ocgs);
removeOCGsFromArray(d, PdfName.ORDER, ocgs);
removeOCGsFromArray(d, PdfName.AS, ocgs);
}
PdfArray ocgsArray = ocproperties.getAsArray(PdfName.OCGS);
if ( ocgsArray != null && ocgsArray.isEmpty() ) {
root.remove(PdfName.OCPROPERTIES);
if ( PdfName.USEOC.equals(root.getAsName(PdfName.PAGEMODE)) ) {
root.remove(PdfName.PAGEMODE);
}
}
}
reader.removeUnusedObjects();
}
/**
* Gets an array from a dictionary and checks if it contains references to OCGs that need to be removed
* @param dict the dictionary
* @param name the name of an array entry
* @param ocgs the removal list
*/
private void removeOCGsFromArray(PdfDictionary dict, PdfName name, Set ocgs) {
if (dict == null)
return;
PdfArray array = dict.getAsArray(name);
if (array == null)
return;
removeOCGsFromArray(array, ocgs);
}
/**
* Searches an array for references to OCGs that need to be removed.
* @param array the array
* @param ocgs the removal list
*/
private void removeOCGsFromArray(PdfArray array, Set ocgs) {
if (array == null)
return;
PdfObject o;
PdfDictionary dict;
List remove = new ArrayList();
for (int i = array.size(); i > 0; ) {
o = array.getDirectObject(--i);
if (o.isDictionary()) {
dict = (PdfDictionary)o;
if (isToBeRemoved(dict, ocgs)) {
remove.add(i);
}
else {
removeOCGsFromArray(dict, PdfName.OCGS, ocgs);
}
}
if (o.isArray()) {
removeOCGsFromArray((PdfArray)o, ocgs);
}
}
for (Integer i : remove) {
array.remove(i);
}
}
/**
* Removes annotations from a page dictionary
* @param page a page dictionary
* @param ocgs a set of names of OCG layers
*/
private void removeAnnots(PdfDictionary page, Set ocgs) {
PdfArray annots = page.getAsArray(PdfName.ANNOTS);
if (annots == null) return;
PdfDictionary annot;
List remove = new ArrayList();
for (int i = annots.size(); i > 0; ) {
annot = annots.getAsDict(--i);
if (isToBeRemoved(annot.getAsDict(PdfName.OC), ocgs)) {
remove.add(i);
}
else {
removeOCGsFromArray(annot.getAsDict(PdfName.A), PdfName.STATE, ocgs);
}
}
for (Integer i : remove) {
annots.remove(i);
}
}
/**
* Removes ocgs from a page resources
* @param page a page dictionary
* @param ocgs a set of names of OCG layers
*/
private void removeProperties(PdfDictionary page, Set ocgs) {
PdfDictionary resources = page.getAsDict(PdfName.RESOURCES);
if (resources == null) return;
PdfDictionary properties = resources.getAsDict(PdfName.PROPERTIES);
if (properties == null) return;
Set names = properties.getKeys();
List remove = new ArrayList();
PdfDictionary dict;
for (PdfName name : names) {
dict = properties.getAsDict(name);
if (isToBeRemoved(dict, ocgs)) {
remove.add(name);
}
else {
removeOCGsFromArray(dict, PdfName.OCGS, ocgs);
}
}
for (PdfName name : remove) {
properties.remove(name);
}
}
/**
* Checks if an OCG dictionary is on the list for removal.
* @param ocg a dictionary
* @param names the removal list
* @return true if the dictionary should be removed
*/
private boolean isToBeRemoved(PdfDictionary ocg, Set names) {
if (ocg == null)
return false;
PdfString n = ocg.getAsString(PdfName.NAME);
if (n == null)
return false;
return names.contains(n.toString());
}
/**
* Uses the OCGParser on a page
* @param parser the OCGParser
* @param page the page dictionary of the page that needs to be parsed.
* @throws IOException
*/
private void parse(OCGParser parser, PdfDictionary page) throws IOException {
PRStream stream = (PRStream)page.getAsStream(PdfName.CONTENTS);
PdfDictionary resources = page.getAsDict(PdfName.RESOURCES);
parser.parse(stream, resources);
}
}