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/*
* Copyright 2002-2017 Drew Noakes
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* More information about this project is available at:
*
* https://drewnoakes.com/code/exif/
* https://github.com/drewnoakes/metadata-extractor
*/
package com.drew.imaging.png;
import com.drew.lang.*;
import com.drew.lang.annotations.NotNull;
import com.drew.metadata.Metadata;
import com.drew.metadata.StringValue;
import com.drew.metadata.file.FileSystemMetadataReader;
import com.drew.metadata.icc.IccReader;
import com.drew.metadata.png.PngChromaticitiesDirectory;
import com.drew.metadata.png.PngDirectory;
import com.drew.metadata.xmp.XmpReader;
import java.io.*;
import java.nio.charset.Charset;
import java.util.*;
import java.util.zip.InflaterInputStream;
/**
* @author Drew Noakes https://drewnoakes.com
*/
public class PngMetadataReader
{
private static Set<PngChunkType> _desiredChunkTypes;
/**
* The PNG spec states that ISO_8859_1 (Latin-1) encoding should be used for:
* <ul>
* <li>"tEXt" and "zTXt" chunks, both for keys and values (https://www.w3.org/TR/PNG/#11tEXt)</li>
* <li>"iCCP" chunks, for the profile name (https://www.w3.org/TR/PNG/#11iCCP)</li>
* <li>"sPLT" chunks, for the palette name (https://www.w3.org/TR/PNG/#11sPLT)</li>
* </ul>
* Note that "iTXt" chunks use UTF-8 encoding (https://www.w3.org/TR/PNG/#11iTXt).
* <p/>
* For more guidance: http://www.w3.org/TR/PNG-Decoders.html#D.Text-chunk-processing
*/
private static Charset _latin1Encoding = Charsets.ISO_8859_1;
static
{
Set<PngChunkType> desiredChunkTypes = new HashSet<PngChunkType>();
desiredChunkTypes.add(PngChunkType.IHDR);
desiredChunkTypes.add(PngChunkType.PLTE);
desiredChunkTypes.add(PngChunkType.tRNS);
desiredChunkTypes.add(PngChunkType.cHRM);
desiredChunkTypes.add(PngChunkType.sRGB);
desiredChunkTypes.add(PngChunkType.gAMA);
desiredChunkTypes.add(PngChunkType.iCCP);
desiredChunkTypes.add(PngChunkType.bKGD);
desiredChunkTypes.add(PngChunkType.tEXt);
desiredChunkTypes.add(PngChunkType.zTXt);
desiredChunkTypes.add(PngChunkType.iTXt);
desiredChunkTypes.add(PngChunkType.tIME);
desiredChunkTypes.add(PngChunkType.pHYs);
desiredChunkTypes.add(PngChunkType.sBIT);
_desiredChunkTypes = Collections.unmodifiableSet(desiredChunkTypes);
}
@NotNull
public static Metadata readMetadata(@NotNull File file) throws PngProcessingException, IOException
{
InputStream inputStream = new FileInputStream(file);
Metadata metadata;
try {
metadata = readMetadata(inputStream);
} finally {
inputStream.close();
}
new FileSystemMetadataReader().read(file, metadata);
return metadata;
}
@NotNull
public static Metadata readMetadata(@NotNull InputStream inputStream) throws PngProcessingException, IOException
{
Iterable<PngChunk> chunks = new PngChunkReader().extract(new StreamReader(inputStream), _desiredChunkTypes);
Metadata metadata = new Metadata();
for (PngChunk chunk : chunks) {
try {
processChunk(metadata, chunk);
} catch (Exception e) {
e.printStackTrace(System.err);
}
}
return metadata;
}
private static void processChunk(@NotNull Metadata metadata, @NotNull PngChunk chunk) throws PngProcessingException, IOException
{
PngChunkType chunkType = chunk.getType();
byte[] bytes = chunk.getBytes();
if (chunkType.equals(PngChunkType.IHDR)) {
PngHeader header = new PngHeader(bytes);
PngDirectory directory = new PngDirectory(PngChunkType.IHDR);
directory.setInt(PngDirectory.TAG_IMAGE_WIDTH, header.getImageWidth());
directory.setInt(PngDirectory.TAG_IMAGE_HEIGHT, header.getImageHeight());
directory.setInt(PngDirectory.TAG_BITS_PER_SAMPLE, header.getBitsPerSample());
directory.setInt(PngDirectory.TAG_COLOR_TYPE, header.getColorType().getNumericValue());
directory.setInt(PngDirectory.TAG_COMPRESSION_TYPE, header.getCompressionType() & 0xFF); // make sure it's unsigned
directory.setInt(PngDirectory.TAG_FILTER_METHOD, header.getFilterMethod());
directory.setInt(PngDirectory.TAG_INTERLACE_METHOD, header.getInterlaceMethod());
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.PLTE)) {
PngDirectory directory = new PngDirectory(PngChunkType.PLTE);
directory.setInt(PngDirectory.TAG_PALETTE_SIZE, bytes.length / 3);
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.tRNS)) {
PngDirectory directory = new PngDirectory(PngChunkType.tRNS);
directory.setInt(PngDirectory.TAG_PALETTE_HAS_TRANSPARENCY, 1);
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.sRGB)) {
int srgbRenderingIntent = bytes[0];
PngDirectory directory = new PngDirectory(PngChunkType.sRGB);
directory.setInt(PngDirectory.TAG_SRGB_RENDERING_INTENT, srgbRenderingIntent);
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.cHRM)) {
PngChromaticities chromaticities = new PngChromaticities(bytes);
PngChromaticitiesDirectory directory = new PngChromaticitiesDirectory();
directory.setInt(PngChromaticitiesDirectory.TAG_WHITE_POINT_X, chromaticities.getWhitePointX());
directory.setInt(PngChromaticitiesDirectory.TAG_WHITE_POINT_Y, chromaticities.getWhitePointY());
directory.setInt(PngChromaticitiesDirectory.TAG_RED_X, chromaticities.getRedX());
directory.setInt(PngChromaticitiesDirectory.TAG_RED_Y, chromaticities.getRedY());
directory.setInt(PngChromaticitiesDirectory.TAG_GREEN_X, chromaticities.getGreenX());
directory.setInt(PngChromaticitiesDirectory.TAG_GREEN_Y, chromaticities.getGreenY());
directory.setInt(PngChromaticitiesDirectory.TAG_BLUE_X, chromaticities.getBlueX());
directory.setInt(PngChromaticitiesDirectory.TAG_BLUE_Y, chromaticities.getBlueY());
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.gAMA)) {
int gammaInt = ByteConvert.toInt32BigEndian(bytes);
new SequentialByteArrayReader(bytes).getInt32();
PngDirectory directory = new PngDirectory(PngChunkType.gAMA);
directory.setDouble(PngDirectory.TAG_GAMMA, gammaInt / 100000.0);
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.iCCP)) {
SequentialReader reader = new SequentialByteArrayReader(bytes);
// Profile Name is 1-79 bytes, followed by the 1 byte null character
byte[] profileNameBytes = reader.getNullTerminatedBytes(79 + 1);
PngDirectory directory = new PngDirectory(PngChunkType.iCCP);
directory.setStringValue(PngDirectory.TAG_ICC_PROFILE_NAME, new StringValue(profileNameBytes, _latin1Encoding));
byte compressionMethod = reader.getInt8();
// Only compression method allowed by the spec is zero: deflate
if (compressionMethod == 0) {
// bytes left for compressed text is:
// total bytes length - (profilenamebytes length + null byte + compression method byte)
int bytesLeft = bytes.length - (profileNameBytes.length + 1 + 1);
byte[] compressedProfile = reader.getBytes(bytesLeft);
try {
InflaterInputStream inflateStream = new InflaterInputStream(new ByteArrayInputStream(compressedProfile));
new IccReader().extract(new RandomAccessStreamReader(inflateStream), metadata, directory);
inflateStream.close();
} catch(java.util.zip.ZipException zex) {
directory.addError(String.format("Exception decompressing PNG iCCP chunk : %s", zex.getMessage()));
metadata.addDirectory(directory);
}
} else {
directory.addError("Invalid compression method value");
}
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.bKGD)) {
PngDirectory directory = new PngDirectory(PngChunkType.bKGD);
directory.setByteArray(PngDirectory.TAG_BACKGROUND_COLOR, bytes);
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.tEXt)) {
SequentialReader reader = new SequentialByteArrayReader(bytes);
// Keyword is 1-79 bytes, followed by the 1 byte null character
StringValue keywordsv = reader.getNullTerminatedStringValue(79 + 1, _latin1Encoding);
String keyword = keywordsv.toString();
// bytes left for text is:
// total bytes length - (Keyword length + null byte)
int bytesLeft = bytes.length - (keywordsv.getBytes().length + 1);
StringValue value = reader.getNullTerminatedStringValue(bytesLeft, _latin1Encoding);
List<KeyValuePair> textPairs = new ArrayList<KeyValuePair>();
textPairs.add(new KeyValuePair(keyword, value));
PngDirectory directory = new PngDirectory(PngChunkType.tEXt);
directory.setObject(PngDirectory.TAG_TEXTUAL_DATA, textPairs);
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.zTXt)) {
SequentialReader reader = new SequentialByteArrayReader(bytes);
// Keyword is 1-79 bytes, followed by the 1 byte null character
StringValue keywordsv = reader.getNullTerminatedStringValue(79 + 1, _latin1Encoding);
String keyword = keywordsv.toString();
byte compressionMethod = reader.getInt8();
// bytes left for compressed text is:
// total bytes length - (Keyword length + null byte + compression method byte)
int bytesLeft = bytes.length - (keywordsv.getBytes().length + 1 + 1);
byte[] textBytes = null;
if (compressionMethod == 0) {
try {
textBytes = StreamUtil.readAllBytes(new InflaterInputStream(new ByteArrayInputStream(bytes, bytes.length - bytesLeft, bytesLeft)));
} catch(java.util.zip.ZipException zex) {
textBytes = null;
PngDirectory directory = new PngDirectory(PngChunkType.zTXt);
directory.addError(String.format("Exception decompressing PNG zTXt chunk with keyword \"%s\": %s", keyword, zex.getMessage()));
metadata.addDirectory(directory);
}
} else {
PngDirectory directory = new PngDirectory(PngChunkType.zTXt);
directory.addError("Invalid compression method value");
metadata.addDirectory(directory);
}
if (textBytes != null) {
if (keyword.equals("XML:com.adobe.xmp")) {
// NOTE in testing images, the XMP has parsed successfully, but we are not extracting tags from it as necessary
new XmpReader().extract(textBytes, metadata);
} else {
List<KeyValuePair> textPairs = new ArrayList<KeyValuePair>();
textPairs.add(new KeyValuePair(keyword, new StringValue(textBytes, _latin1Encoding)));
PngDirectory directory = new PngDirectory(PngChunkType.zTXt);
directory.setObject(PngDirectory.TAG_TEXTUAL_DATA, textPairs);
metadata.addDirectory(directory);
}
}
} else if (chunkType.equals(PngChunkType.iTXt)) {
SequentialReader reader = new SequentialByteArrayReader(bytes);
// Keyword is 1-79 bytes, followed by the 1 byte null character
StringValue keywordsv = reader.getNullTerminatedStringValue(79 + 1, _latin1Encoding);
String keyword = keywordsv.toString();
byte compressionFlag = reader.getInt8();
byte compressionMethod = reader.getInt8();
// TODO we currently ignore languageTagBytes and translatedKeywordBytes
byte[] languageTagBytes = reader.getNullTerminatedBytes(bytes.length);
byte[] translatedKeywordBytes = reader.getNullTerminatedBytes(bytes.length);
// bytes left for compressed text is:
// total bytes length - (Keyword length + null byte + comp flag byte + comp method byte + lang length + null byte + translated length + null byte)
int bytesLeft = bytes.length - (keywordsv.getBytes().length + 1 + 1 + 1 + languageTagBytes.length + 1 + translatedKeywordBytes.length + 1);
byte[] textBytes = null;
if (compressionFlag == 0) {
textBytes = reader.getNullTerminatedBytes(bytesLeft);
} else if (compressionFlag == 1) {
if (compressionMethod == 0) {
try {
textBytes = StreamUtil.readAllBytes(new InflaterInputStream(new ByteArrayInputStream(bytes, bytes.length - bytesLeft, bytesLeft)));
} catch(java.util.zip.ZipException zex) {
textBytes = null;
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.addError(String.format("Exception decompressing PNG iTXt chunk with keyword \"%s\": %s", keyword, zex.getMessage()));
metadata.addDirectory(directory);
}
} else {
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.addError("Invalid compression method value");
metadata.addDirectory(directory);
}
} else {
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.addError("Invalid compression flag value");
metadata.addDirectory(directory);
}
if (textBytes != null) {
if (keyword.equals("XML:com.adobe.xmp")) {
// NOTE in testing images, the XMP has parsed successfully, but we are not extracting tags from it as necessary
new XmpReader().extract(textBytes, metadata);
} else {
List<KeyValuePair> textPairs = new ArrayList<KeyValuePair>();
textPairs.add(new KeyValuePair(keyword, new StringValue(textBytes, _latin1Encoding)));
PngDirectory directory = new PngDirectory(PngChunkType.iTXt);
directory.setObject(PngDirectory.TAG_TEXTUAL_DATA, textPairs);
metadata.addDirectory(directory);
}
}
} else if (chunkType.equals(PngChunkType.tIME)) {
SequentialByteArrayReader reader = new SequentialByteArrayReader(bytes);
int year = reader.getUInt16();
int month = reader.getUInt8();
int day = reader.getUInt8();
int hour = reader.getUInt8();
int minute = reader.getUInt8();
int second = reader.getUInt8();
PngDirectory directory = new PngDirectory(PngChunkType.tIME);
if (DateUtil.isValidDate(year, month - 1, day) && DateUtil.isValidTime(hour, minute, second)) {
String dateString = String.format("%04d:%02d:%02d %02d:%02d:%02d", year, month, day, hour, minute, second);
directory.setString(PngDirectory.TAG_LAST_MODIFICATION_TIME, dateString);
} else {
directory.addError(String.format(
"PNG tIME data describes an invalid date/time: year=%d month=%d day=%d hour=%d minute=%d second=%d",
year, month, day, hour, minute, second));
}
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.pHYs)) {
SequentialByteArrayReader reader = new SequentialByteArrayReader(bytes);
int pixelsPerUnitX = reader.getInt32();
int pixelsPerUnitY = reader.getInt32();
byte unitSpecifier = reader.getInt8();
PngDirectory directory = new PngDirectory(PngChunkType.pHYs);
directory.setInt(PngDirectory.TAG_PIXELS_PER_UNIT_X, pixelsPerUnitX);
directory.setInt(PngDirectory.TAG_PIXELS_PER_UNIT_Y, pixelsPerUnitY);
directory.setInt(PngDirectory.TAG_UNIT_SPECIFIER, unitSpecifier);
metadata.addDirectory(directory);
} else if (chunkType.equals(PngChunkType.sBIT)) {
PngDirectory directory = new PngDirectory(PngChunkType.sBIT);
directory.setByteArray(PngDirectory.TAG_SIGNIFICANT_BITS, bytes);
metadata.addDirectory(directory);
}
}
}
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