PdfCanvasParser.java
/*
This file is part of the iText (R) project.
Copyright (c) 1998-2025 Apryse Group NV
Authors: Apryse Software.
This program is offered under a commercial and under the AGPL license.
For commercial licensing, contact us at https://itextpdf.com/sales. For AGPL licensing, see below.
AGPL licensing:
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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 <https://www.gnu.org/licenses/>.
*/
package com.itextpdf.kernel.pdf.canvas.parser.util;
import com.itextpdf.commons.utils.MessageFormatUtil;
import com.itextpdf.kernel.exceptions.PdfException;
import com.itextpdf.io.source.PdfTokenizer;
import com.itextpdf.kernel.exceptions.KernelExceptionMessageConstant;
import com.itextpdf.kernel.pdf.PdfArray;
import com.itextpdf.kernel.pdf.PdfDictionary;
import com.itextpdf.kernel.pdf.PdfLiteral;
import com.itextpdf.kernel.pdf.PdfName;
import com.itextpdf.kernel.pdf.PdfNumber;
import com.itextpdf.kernel.pdf.PdfObject;
import com.itextpdf.kernel.pdf.PdfResources;
import com.itextpdf.kernel.pdf.PdfStream;
import com.itextpdf.kernel.pdf.PdfString;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* Parses the page or form XObject content.
*/
public class PdfCanvasParser {
/**
* Holds value of property tokeniser.
*/
private PdfTokenizer tokeniser;
private PdfResources currentResources;
/**
* Creates a new instance of PdfContentParser
* @param tokeniser the tokeniser with the content
*/
public PdfCanvasParser(PdfTokenizer tokeniser) {
this.tokeniser = tokeniser;
}
/**
* Creates a new instance of PdfContentParser
* @param tokeniser the tokeniser with the content
* @param currentResources current resources of the content stream.
* It is optional parameter, which is used for performance improvements of specific cases of
* inline images parsing.
*/
public PdfCanvasParser(PdfTokenizer tokeniser, PdfResources currentResources) {
this.tokeniser = tokeniser;
this.currentResources = currentResources;
}
/**
* Parses a single command from the content. Each command is output as an array of arguments
* having the command itself as the last element. The returned array will be empty if the
* end of content was reached.
* <br>
* A specific behaviour occurs when inline image is encountered (BI command):
* in that case, parser would continue parsing until it meets EI - end of the inline image;
* as a result in this case it will return an array with inline image dictionary and image bytes
* encapsulated in PdfStream object as first element and EI command as second element.
* @param ls an <CODE>ArrayList</CODE> to use. It will be cleared before using. If it's
* <CODE>null</CODE> will create a new <CODE>ArrayList</CODE>
* @return the same <CODE>ArrayList</CODE> given as argument or a new one
* @throws IOException on error
*/
public List<PdfObject> parse(List<PdfObject> ls) throws IOException {
if (ls == null)
ls = new ArrayList<>();
else
ls.clear();
PdfObject ob = null;
while ((ob = readObject()) != null) {
ls.add(ob);
if (tokeniser.getTokenType() == PdfTokenizer.TokenType.Other) {
if ("BI".equals(ob.toString())) {
PdfStream inlineImageAsStream = InlineImageParsingUtils.parse(this, currentResources.getResource(PdfName.ColorSpace));
ls.clear();
ls.add(inlineImageAsStream);
ls.add(new PdfLiteral("EI"));
}
break;
}
}
return ls;
}
/**
* Gets the tokeniser.
* @return the tokeniser.
*/
public PdfTokenizer getTokeniser() {
return this.tokeniser;
}
/**
* Sets the tokeniser.
* @param tokeniser the tokeniser
*/
public void setTokeniser(PdfTokenizer tokeniser) {
this.tokeniser = tokeniser;
}
/**
* Reads a dictionary. The tokeniser must be positioned past the "<<" token.
* @return the dictionary
* @throws IOException on error
*/
public PdfDictionary readDictionary() throws IOException {
PdfDictionary dic = new PdfDictionary();
while (true) {
if (!nextValidToken())
throw new PdfException(KernelExceptionMessageConstant.UNEXPECTED_END_OF_FILE);
if (tokeniser.getTokenType() == PdfTokenizer.TokenType.EndDic)
break;
if (tokeniser.getTokenType() != PdfTokenizer.TokenType.Name)
tokeniser.throwError(
KernelExceptionMessageConstant.THIS_DICTIONARY_KEY_IS_NOT_A_NAME, tokeniser.getStringValue());
PdfName name = new PdfName(tokeniser.getStringValue());
PdfObject obj = readObject();
dic.put(name, obj);
}
return dic;
}
/**
* Reads an array. The tokeniser must be positioned past the "[" token.
* @return an array
* @throws IOException on error
*/
public PdfArray readArray() throws IOException {
PdfArray array = new PdfArray();
while (true) {
PdfObject obj = readObject();
if (!obj.isArray() && tokeniser.getTokenType() == PdfTokenizer.TokenType.EndArray) {
break;
}
if (tokeniser.getTokenType() == PdfTokenizer.TokenType.EndDic && obj.getType() != PdfObject.DICTIONARY) {
tokeniser.throwError(MessageFormatUtil.format(KernelExceptionMessageConstant.UNEXPECTED_TOKEN, ">>"));
}
array.add(obj);
}
return array;
}
/**
* Reads a pdf object.
* @return the pdf object
* @throws IOException on error
*/
public PdfObject readObject() throws IOException {
if (!nextValidToken())
return null;
final PdfTokenizer.TokenType type = tokeniser.getTokenType();
switch (type) {
case StartDic: {
PdfDictionary dic = readDictionary();
return dic;
}
case StartArray:
return readArray();
case String:
PdfString str = new PdfString(tokeniser.getDecodedStringContent()).setHexWriting(tokeniser.isHexString());
return str;
case Name:
return new PdfName(tokeniser.getByteContent());
case Number:
//use PdfNumber(byte[]) here, as in this case number parsing won't happen until it's needed.
return new PdfNumber(tokeniser.getByteContent());
default:
return new PdfLiteral(tokeniser.getByteContent());
}
}
/**
* Reads the next token skipping over the comments.
* @return <CODE>true</CODE> if a token was read, <CODE>false</CODE> if the end of content was reached
* @throws IOException on error
*/
public boolean nextValidToken() throws IOException {
while (tokeniser.nextToken()) {
if (tokeniser.getTokenType() == PdfTokenizer.TokenType.Comment)
continue;
return true;
}
return false;
}
}