com.itextpdf.kernel.pdf.canvas.parser.util.InlineImageParsingUtils Maven / Gradle / Ivy
/*
This file is part of the iText (R) project.
Copyright (c) 1998-2019 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
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package com.itextpdf.kernel.pdf.canvas.parser.util;
import com.itextpdf.io.source.PdfTokenizer;
import com.itextpdf.kernel.PdfException;
import com.itextpdf.kernel.pdf.PdfArray;
import com.itextpdf.kernel.pdf.PdfDictionary;
import com.itextpdf.kernel.pdf.PdfName;
import com.itextpdf.kernel.pdf.PdfNumber;
import com.itextpdf.kernel.pdf.PdfObject;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfStream;
import com.itextpdf.kernel.pdf.filters.DoNothingFilter;
import com.itextpdf.kernel.pdf.filters.FilterHandlers;
import com.itextpdf.kernel.pdf.filters.IFilterHandler;
import com.itextpdf.kernel.pdf.filters.FlateDecodeStrictFilter;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
/**
* Utility methods to help with processing of inline images
*/
public final class InlineImageParsingUtils {
private static final byte[] EI = new byte[]{(byte)'E', (byte)'I'};
private InlineImageParsingUtils() {
}
/**
* Simple class in case users need to differentiate an exception from processing
* inline images vs other exceptions
*/
public static class InlineImageParseException extends PdfException implements Serializable {
private static final long serialVersionUID = 233760879000268548L;
public InlineImageParseException(String message) {
super(message);
}
}
/**
* Map between key abbreviations allowed in dictionary of inline images and their
* equivalent image dictionary keys
*/
private static final Map inlineImageEntryAbbreviationMap;
/**
* Map between value abbreviations allowed in dictionary of inline images for COLORSPACE
*/
private static final Map inlineImageColorSpaceAbbreviationMap;
/**
* Map between value abbreviations allowed in dictionary of inline images for FILTER
*/
private static final Map inlineImageFilterAbbreviationMap;
static { // static initializer
// Map between key abbreviations allowed in dictionary of inline images and their
// equivalent image dictionary keys
inlineImageEntryAbbreviationMap = new HashMap<>();
// allowed entries - just pass these through
inlineImageEntryAbbreviationMap.put(PdfName.BitsPerComponent, PdfName.BitsPerComponent);
inlineImageEntryAbbreviationMap.put(PdfName.ColorSpace, PdfName.ColorSpace);
inlineImageEntryAbbreviationMap.put(PdfName.Decode, PdfName.Decode);
inlineImageEntryAbbreviationMap.put(PdfName.DecodeParms, PdfName.DecodeParms);
inlineImageEntryAbbreviationMap.put(PdfName.Filter, PdfName.Filter);
inlineImageEntryAbbreviationMap.put(PdfName.Height, PdfName.Height);
inlineImageEntryAbbreviationMap.put(PdfName.ImageMask, PdfName.ImageMask);
inlineImageEntryAbbreviationMap.put(PdfName.Intent, PdfName.Intent);
inlineImageEntryAbbreviationMap.put(PdfName.Interpolate, PdfName.Interpolate);
inlineImageEntryAbbreviationMap.put(PdfName.Width, PdfName.Width);
// abbreviations - transform these to corresponding correct values
inlineImageEntryAbbreviationMap.put(new PdfName("BPC"), PdfName.BitsPerComponent);
inlineImageEntryAbbreviationMap.put(new PdfName("CS"), PdfName.ColorSpace);
inlineImageEntryAbbreviationMap.put(new PdfName("D"), PdfName.Decode);
inlineImageEntryAbbreviationMap.put(new PdfName("DP"), PdfName.DecodeParms);
inlineImageEntryAbbreviationMap.put(new PdfName("F"), PdfName.Filter);
inlineImageEntryAbbreviationMap.put(new PdfName("H"), PdfName.Height);
inlineImageEntryAbbreviationMap.put(new PdfName("IM"), PdfName.ImageMask);
inlineImageEntryAbbreviationMap.put(new PdfName("I"), PdfName.Interpolate);
inlineImageEntryAbbreviationMap.put(new PdfName("W"), PdfName.Width);
// Map between value abbreviations allowed in dictionary of inline images for COLORSPACE
inlineImageColorSpaceAbbreviationMap = new HashMap<>();
inlineImageColorSpaceAbbreviationMap.put(new PdfName("G"), PdfName.DeviceGray);
inlineImageColorSpaceAbbreviationMap.put(new PdfName("RGB"), PdfName.DeviceRGB);
inlineImageColorSpaceAbbreviationMap.put(new PdfName("CMYK"), PdfName.DeviceCMYK);
inlineImageColorSpaceAbbreviationMap.put(new PdfName("I"), PdfName.Indexed);
// Map between value abbreviations allowed in dictionary of inline images for FILTER
inlineImageFilterAbbreviationMap = new HashMap();
inlineImageFilterAbbreviationMap.put(new PdfName("AHx"), PdfName.ASCIIHexDecode);
inlineImageFilterAbbreviationMap.put(new PdfName("A85"), PdfName.ASCII85Decode);
inlineImageFilterAbbreviationMap.put(new PdfName("LZW"), PdfName.LZWDecode);
inlineImageFilterAbbreviationMap.put(new PdfName("Fl"), PdfName.FlateDecode);
inlineImageFilterAbbreviationMap.put(new PdfName("RL"), PdfName.RunLengthDecode);
inlineImageFilterAbbreviationMap.put(new PdfName("CCF"), PdfName.CCITTFaxDecode);
inlineImageFilterAbbreviationMap.put(new PdfName("DCT"), PdfName.DCTDecode);
}
/**
* Parses an inline image from the provided content parser. The parser must be positioned immediately following the BI operator in the content stream.
* The parser will be left with current position immediately following the EI operator that terminates the inline image
*
* @param ps the content parser to use for reading the image.
* @param colorSpaceDic a color space dictionary
* @return the parsed image
* @throws IOException if anything goes wring with the parsing
* @throws InlineImageParseException if parsing of the inline image failed due to issues specific to inline image processing
*/
public static PdfStream parse(PdfCanvasParser ps, PdfDictionary colorSpaceDic) throws IOException {
PdfDictionary inlineImageDict = parseDictionary(ps);
byte[] samples = parseSamples(inlineImageDict, colorSpaceDic, ps);
PdfStream inlineImageAsStreamObject = new PdfStream(samples);
inlineImageAsStreamObject.putAll(inlineImageDict);
return inlineImageAsStreamObject;
}
/**
* Parses the next inline image dictionary from the parser. The parser must be positioned immediately following the BI operator.
* The parser will be left with position immediately following the whitespace character that follows the ID operator that ends the inline image dictionary.
*
* @param ps the parser to extract the embedded image information from
* @return the dictionary for the inline image, with any abbreviations converted to regular image dictionary keys and values
* @throws IOException if the parse fails
*/
private static PdfDictionary parseDictionary(PdfCanvasParser ps) throws IOException {
// by the time we get to here, we have already parsed the BI operator
PdfDictionary dict = new PdfDictionary();
for (PdfObject key = ps.readObject(); key != null && !"ID".equals(key.toString()); key = ps.readObject()) {
PdfObject value = ps.readObject();
PdfName resolvedKey = inlineImageEntryAbbreviationMap.get((PdfName) key);
if (resolvedKey == null) {
resolvedKey = (PdfName) key;
}
dict.put(resolvedKey, getAlternateValue(resolvedKey, value));
}
int ch = ps.getTokeniser().read();
if (!PdfTokenizer.isWhitespace(ch))
throw new InlineImageParseException(PdfException.UnexpectedCharacter1FoundAfterIDInInlineImage).setMessageParams(ch);
return dict;
}
/**
* Transforms value abbreviations into their corresponding real value
*
* @param key the key that the value is for
* @param value the value that might be an abbreviation
* @return if value is an allowed abbreviation for the key, the expanded value for that abbreviation. Otherwise, value is returned without modification
*/
private static PdfObject getAlternateValue(PdfName key, PdfObject value) {
if (key == PdfName.Filter) {
if (value instanceof PdfName) {
PdfName altValue = inlineImageFilterAbbreviationMap.get((PdfName) value);
if (altValue != null) {
return altValue;
}
} else if (value instanceof PdfArray) {
PdfArray array = ((PdfArray) value);
PdfArray altArray = new PdfArray();
int count = array.size();
for (int i = 0; i < count; i++) {
altArray.add(getAlternateValue(key, array.get(i)));
}
return altArray;
}
} else if (key == PdfName.ColorSpace && value instanceof PdfName) {
PdfName altValue = inlineImageColorSpaceAbbreviationMap.get((PdfName) value);
if (altValue != null) {
return altValue;
}
}
return value;
}
/**
* @param colorSpaceName the name of the color space. If null, a bi-tonal (black and white) color space is assumed.
* @return the components per pixel for the specified color space
*/
private static int getComponentsPerPixel(PdfName colorSpaceName, PdfDictionary colorSpaceDic) {
if (colorSpaceName == null)
return 1;
if (colorSpaceName.equals(PdfName.DeviceGray))
return 1;
if (colorSpaceName.equals(PdfName.DeviceRGB))
return 3;
if (colorSpaceName.equals(PdfName.DeviceCMYK))
return 4;
if (colorSpaceDic != null) {
PdfArray colorSpace = colorSpaceDic.getAsArray(colorSpaceName);
if (colorSpace != null) {
if (PdfName.Indexed.equals(colorSpace.getAsName(0))) {
return 1;
}
} else {
PdfName tempName = colorSpaceDic.getAsName(colorSpaceName);
if (tempName != null) {
return getComponentsPerPixel(tempName, colorSpaceDic);
}
}
}
throw new InlineImageParseException(PdfException.UnexpectedColorSpace1).setMessageParams(colorSpaceName);
}
/**
* Computes the number of unfiltered bytes that each row of the image will contain.
* If the number of bytes results in a partial terminating byte, this number is rounded up
* per the PDF specification
*
* @param imageDictionary the dictionary of the inline image
* @return the number of bytes per row of the image
*/
private static int computeBytesPerRow(PdfDictionary imageDictionary, PdfDictionary colorSpaceDic) {
PdfNumber wObj = imageDictionary.getAsNumber(PdfName.Width);
PdfNumber bpcObj = imageDictionary.getAsNumber(PdfName.BitsPerComponent);
int cpp = getComponentsPerPixel(imageDictionary.getAsName(PdfName.ColorSpace), colorSpaceDic);
int w = wObj.intValue();
int bpc = bpcObj != null ? bpcObj.intValue() : 1;
return (w * bpc * cpp + 7) / 8;
}
/**
* Parses the samples of the image from the underlying content parser, ignoring all filters.
* The parser must be positioned immediately after the ID operator that ends the inline image's dictionary.
* The parser will be left positioned immediately following the EI operator.
* This is primarily useful if no filters have been applied.
*
* @param imageDictionary the dictionary of the inline image
* @param ps the content parser
* @return the samples of the image
* @throws IOException if anything bad happens during parsing
*/
private static byte[] parseUnfilteredSamples(PdfDictionary imageDictionary, PdfDictionary colorSpaceDic, PdfCanvasParser ps) throws IOException {
// special case: when no filter is specified, we just read the number of bits
// per component, multiplied by the width and height.
if (imageDictionary.containsKey(PdfName.Filter))
throw new IllegalArgumentException("Dictionary contains filters");
PdfNumber h = imageDictionary.getAsNumber(PdfName.Height);
int bytesToRead = computeBytesPerRow(imageDictionary, colorSpaceDic) * h.intValue();
byte[] bytes = new byte[bytesToRead];
PdfTokenizer tokeniser = ps.getTokeniser();
int shouldBeWhiteSpace = tokeniser.read(); // skip next character (which better be a whitespace character - I suppose we could check for this)
// from the PDF spec: Unless the image uses ASCIIHexDecode or ASCII85Decode as one of its filters, the ID operator shall be followed by a single white-space character, and the next character shall be interpreted as the first byte of image data.
// unfortunately, we've seen some PDFs where there is no space following the ID, so we have to capture this case and handle it
int startIndex = 0;
if (!PdfTokenizer.isWhitespace(shouldBeWhiteSpace) || shouldBeWhiteSpace == 0) { // tokeniser treats 0 as whitespace, but for our purposes, we shouldn't
bytes[0] = (byte) shouldBeWhiteSpace;
startIndex++;
}
for (int i = startIndex; i < bytesToRead; i++) {
int ch = tokeniser.read();
if (ch == -1)
throw new InlineImageParseException(PdfException.EndOfContentStreamReachedBeforeEndOfImageData);
bytes[i] = (byte) ch;
}
PdfObject ei = ps.readObject();
if (!ei.toString().equals("EI")) {
// Some PDF producers seem to add another non-whitespace character after the image data.
// Let's try to handle that case here.
PdfObject ei2 = ps.readObject();
if (!ei2.toString().equals("EI"))
throw new InlineImageParseException(PdfException.OperatorEINotFoundAfterEndOfImageData);
}
return bytes;
}
/**
* Parses the samples of the image from the underlying content parser, accounting for filters
* The parser must be positioned immediately after the ID operator that ends the inline image's dictionary.
* The parser will be left positioned immediately following the EI operator.
* Note:This implementation does not actually apply the filters at this time
*
* @param imageDictionary the dictionary of the inline image
* @param ps the content parser
* @return the samples of the image
* @throws IOException if anything bad happens during parsing
*/
private static byte[] parseSamples(PdfDictionary imageDictionary, PdfDictionary colorSpaceDic, PdfCanvasParser ps) throws IOException {
// by the time we get to here, we have already parsed the ID operator
if (!imageDictionary.containsKey(PdfName.Filter) && imageColorSpaceIsKnown(imageDictionary, colorSpaceDic)) {
return parseUnfilteredSamples(imageDictionary, colorSpaceDic, ps);
}
// read all content until we reach an EI operator followed by whitespace.
// then decode the content stream to check that bytes that were parsed are really all image bytes
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int ch;
int found = 0;
PdfTokenizer tokeniser = ps.getTokeniser();
while ((ch = tokeniser.read()) != -1) {
if (ch == 'E') {
baos.write(EI, 0, found); // probably some bytes were preserved so write them
found = 1; // just preserve 'E' and do not write it immediately
} else if (found == 1 && ch == 'I') {
found = 2; // just preserve 'EI' and do not write it immediately
} else {
if (found == 2 && PdfTokenizer.isWhitespace(ch)) {
byte[] tmp = baos.toByteArray();
if (inlineImageStreamBytesAreComplete(tmp, imageDictionary)) {
return tmp;
}
}
baos.write(EI, 0, found); // probably some bytes were preserved so write them
baos.write(ch);
found = 0;
}
}
throw new InlineImageParseException(PdfException.CannotFindImageDataOrEI);
}
private static boolean imageColorSpaceIsKnown(PdfDictionary imageDictionary, PdfDictionary colorSpaceDic) {
PdfName cs = imageDictionary.getAsName(PdfName.ColorSpace);
if (cs == null || cs.equals(PdfName.DeviceGray) || cs.equals(PdfName.DeviceRGB) || cs.equals(PdfName.DeviceCMYK))
return true;
return colorSpaceDic != null && colorSpaceDic.containsKey(cs);
}
/**
* This method acts like a check that bytes that were parsed are really all image bytes. If it's true,
* then decoding will succeed, but if not all image bytes were read and "EI" bytes were just a part of the image,
* then decoding should fail.
* Not the best solution, but probably there is no better and more reliable way to check this.
*
* Drawbacks: slow; images with DCTDecode, JBIG2Decode and JPXDecode filters couldn't be checked as iText doesn't
* support these filters; what if decoding will succeed eventhough it's not all bytes?; also I'm not sure that all
* filters throw an exception in case data is corrupted (For example, FlateDecodeFilter seems not to throw an exception).
**/
private static boolean inlineImageStreamBytesAreComplete(byte[] samples, PdfDictionary imageDictionary) {
try {
Map filters = new HashMap<>(FilterHandlers.getDefaultFilterHandlers());
DoNothingFilter stubfilter = new DoNothingFilter();
filters.put(PdfName.DCTDecode, stubfilter);
filters.put(PdfName.JBIG2Decode, stubfilter);
filters.put(PdfName.JPXDecode, stubfilter);
filters.put(PdfName.FlateDecode, new FlateDecodeStrictFilter());
PdfReader.decodeBytes(samples, imageDictionary, filters);
} catch (Exception ex) {
return false;
}
return true;
}
}