* Below is an example of getting EXIF data from IFD 0 and EXIF IFD using the parser. *
* void parse() {
* ExifParser parser = ExifParser.parse(mImageInputStream,
* ExifParser.OPTION_IFD_0 | ExifParser.OPTIONS_IFD_EXIF);
* int event = parser.next();
* while (event != ExifParser.EVENT_END) {
* switch (event) {
* case ExifParser.EVENT_START_OF_IFD:
* break;
* case ExifParser.EVENT_NEW_TAG:
* ExifTag tag = parser.getTag();
* if (!tag.hasValue()) {
* parser.registerForTagValue(tag);
* } else {
* processTag(tag);
* }
* break;
* case ExifParser.EVENT_VALUE_OF_REGISTERED_TAG:
* tag = parser.getTag();
* if (tag.getDataType() != ExifTag.TYPE_UNDEFINED) {
* processTag(tag);
* }
* break;
* }
* event = parser.next();
* }
* }
*
* void processTag(ExifTag tag) {
* // process the tag as you like.
* }
*
*/
public class ExifParser {
private static final String TAG = "ExifParser";
/**
* When the parser reaches a new IFD area. Call
* {@link #getCurrentIfd()} to know which IFD we are in.
*/
public static final int EVENT_START_OF_IFD = 0;
/**
* When the parser reaches a new tag. Call {@link #getTag()}to get the
* corresponding tag.
*/
public static final int EVENT_NEW_TAG = 1;
/**
* When the parser reaches the value area of tag that is registered by
* {@link #registerForTagValue(ExifTag)} previously. Call
* {@link #getTag()} to get the corresponding tag.
*/
public static final int EVENT_VALUE_OF_REGISTERED_TAG = 2;
/**
* When the parser reaches the compressed image area.
*/
public static final int EVENT_COMPRESSED_IMAGE = 3;
/**
* When the parser reaches the uncompressed image strip.
* Call {@link #getStripIndex()} to get the index of the strip.
* @see #getStripIndex()
* @see #getStripCount()
*/
public static final int EVENT_UNCOMPRESSED_STRIP = 4;
/**
* When there is nothing more to parse.
*/
public static final int EVENT_END = 5;
/**
* Option bit to request to parse IFD0.
*/
public static final int OPTION_IFD_0 = 1 << 0;
/**
* Option bit to request to parse IFD1.
*/
public static final int OPTION_IFD_1 = 1 << 1;
/**
* Option bit to request to parse Exif-IFD.
*/
public static final int OPTION_IFD_EXIF = 1 << 2;
/**
* Option bit to request to parse GPS-IFD.
*/
public static final int OPTION_IFD_GPS = 1 << 3;
/**
* Option bit to request to parse Interoperability-IFD.
*/
public static final int OPTION_IFD_INTEROPERABILITY = 1 << 4;
/**
* Option bit to request to parse thumbnail.
*/
public static final int OPTION_THUMBNAIL = 1 << 5;
private static final int EXIF_HEADER = 0x45786966; // EXIF header "Exif"
private static final short EXIF_HEADER_TAIL = (short) 0x0000; // EXIF header in APP1
// TIFF header
private static final short LITTLE_ENDIAN_TAG = (short) 0x4949; // "II"
private static final short BIG_ENDIAN_TAG = (short) 0x4d4d; // "MM"
private static final short TIFF_HEADER_TAIL = 0x002A;
private static final int TAG_SIZE = 12;
private static final int OFFSET_SIZE = 2;
private static final Charset US_ASCII = Charset.forName("US-ASCII");
private static final int DEFAULT_IFD0_OFFSET = 8;
private final CountedDataInputStream mTiffStream;
private final int mOptions;
private int mIfdStartOffset = 0;
private int mNumOfTagInIfd = 0;
private int mIfdType;
private ExifTag mTag;
private ImageEvent mImageEvent;
private int mStripCount;
private ExifTag mStripSizeTag;
private ExifTag mJpegSizeTag;
private boolean mNeedToParseOffsetsInCurrentIfd;
private boolean mContainExifData = false;
private int mApp1End;
private byte[] mDataAboveIfd0;
private int mIfd0Position;
private final TreeMap* * For {@link #EVENT_NEW_TAG}, the tag may not contain the value if the size of the value is * greater than 4 bytes. One should call {@link ExifTag#hasValue()} to check if the tag * contains value. * If there is no value,call {@link #registerForTagValue(ExifTag)} to have the parser emit * {@link #EVENT_VALUE_OF_REGISTERED_TAG} when it reaches the area pointed by the offset. * *
* When {@link #EVENT_VALUE_OF_REGISTERED_TAG} is emitted, the value of the tag will have * already been read except for tags of undefined type. For tags of undefined type, call * one of the read methods to get the value. * * @see #registerForTagValue(ExifTag) * @see #read(byte[]) * @see #read(byte[], int, int) * @see #readLong() * @see #readRational() * @see #readString(int) * @see #readString(int, Charset) */ public ExifTag getTag() { return mTag; } /** * Gets number of tags in the current IFD area. */ public int getTagCountInCurrentIfd() { return mNumOfTagInIfd; } /** * Gets the ID of current IFD. * * @see IfdId#TYPE_IFD_0 * @see IfdId#TYPE_IFD_1 * @see IfdId#TYPE_IFD_GPS * @see IfdId#TYPE_IFD_INTEROPERABILITY * @see IfdId#TYPE_IFD_EXIF */ public int getCurrentIfd() { return mIfdType; } /** * When receiving {@link #EVENT_UNCOMPRESSED_STRIP}, * call this function to get the index of this strip. * @see #getStripCount() */ public int getStripIndex() { return mImageEvent.stripIndex; } /** * When receiving {@link #EVENT_UNCOMPRESSED_STRIP}, call this function to get the number * of strip data. * @see #getStripIndex() */ public int getStripCount() { return mStripCount; } /** * When receiving {@link #EVENT_UNCOMPRESSED_STRIP}, call this function to get the strip size. */ public int getStripSize() { if (mStripSizeTag == null) return 0; return (int) mStripSizeTag.getValueAt(0); } /** * When receiving {@link #EVENT_COMPRESSED_IMAGE}, call this function to get the image data * size. */ public int getCompressedImageSize() { if (mJpegSizeTag == null) return 0; return (int) mJpegSizeTag.getValueAt(0); } private void skipTo(int offset) throws IOException { mTiffStream.skipTo(offset); while (!mCorrespondingEvent.isEmpty() && mCorrespondingEvent.firstKey() < offset) { mCorrespondingEvent.pollFirstEntry(); } } /** * When getting {@link #EVENT_NEW_TAG} in the tag area of IFD, * the tag may not contain the value if the size of the value is greater than 4 bytes. * When the value is not available here, call this method so that the parser will emit * {@link #EVENT_VALUE_OF_REGISTERED_TAG} when it reaches the area where the value is located. * @see #EVENT_VALUE_OF_REGISTERED_TAG */ public void registerForTagValue(ExifTag tag) { mCorrespondingEvent.put(tag.getOffset(), new ExifTagEvent(tag, true)); } private void registerIfd(int ifdType, long offset) { // Cast unsigned int to int since the offset is always smaller // than the size of APP1 (65536) mCorrespondingEvent.put((int) offset, new IfdEvent(ifdType, isIfdRequested(ifdType))); } private void registerCompressedImage(long offset) { mCorrespondingEvent.put((int) offset, new ImageEvent(EVENT_COMPRESSED_IMAGE)); } private void registerUncompressedStrip(int stripIndex, long offset) { mCorrespondingEvent.put((int) offset, new ImageEvent(EVENT_UNCOMPRESSED_STRIP , stripIndex)); } private ExifTag readTag() throws IOException, ExifInvalidFormatException { short tagId = mTiffStream.readShort(); short dataFormat = mTiffStream.readShort(); long numOfComp = mTiffStream.readUnsignedInt(); if (numOfComp > Integer.MAX_VALUE) { throw new ExifInvalidFormatException( "Number of component is larger then Integer.MAX_VALUE"); } // Some invalid image file contains invalid data type. Ignore those tags if (!ExifTag.isValidType(dataFormat)) { Log.w(TAG, String.format("Tag %04x: Invalid data type %d", tagId, dataFormat)); mTiffStream.skip(4); return null; } ExifTag tag = new ExifTag(tagId, dataFormat, (int) numOfComp, mIfdType); int dataSize = tag.getDataSize(); if (dataSize > 4) { long offset = mTiffStream.readUnsignedInt(); if (offset > Integer.MAX_VALUE) { throw new ExifInvalidFormatException( "offset is larger then Integer.MAX_VALUE"); } // Some invalid images put some undefined data before IFD0. // Read the data here. if ((offset < mIfd0Position) && (dataFormat == ExifTag.TYPE_UNDEFINED)) { byte[] buf = new byte[(int) numOfComp]; System.arraycopy(mDataAboveIfd0, (int) offset - DEFAULT_IFD0_OFFSET, buf, 0, (int) numOfComp); tag.setValue(buf); } else { tag.setOffset((int) offset); } } else { readFullTagValue(tag); mTiffStream.skip(4 - dataSize); } return tag; } /** * Check the tag, if the tag is one of the offset tag that points to the IFD or image the * caller is interested in, register the IFD or image. */ private void checkOffsetOrImageTag(ExifTag tag) { // Some invalid formattd image contains tag with 0 size. if (tag.getComponentCount() == 0) { return; } switch (tag.getTagId()) { case ExifTag.TAG_EXIF_IFD: if (isIfdRequested(IfdId.TYPE_IFD_EXIF) || isIfdRequested(IfdId.TYPE_IFD_INTEROPERABILITY)) { registerIfd(IfdId.TYPE_IFD_EXIF, tag.getValueAt(0)); } break; case ExifTag.TAG_GPS_IFD: if (isIfdRequested(IfdId.TYPE_IFD_GPS)) { registerIfd(IfdId.TYPE_IFD_GPS, tag.getValueAt(0)); } break; case ExifTag.TAG_INTEROPERABILITY_IFD: if (isIfdRequested(IfdId.TYPE_IFD_INTEROPERABILITY)) { registerIfd(IfdId.TYPE_IFD_INTEROPERABILITY, tag.getValueAt(0)); } break; case ExifTag.TAG_JPEG_INTERCHANGE_FORMAT: if (isThumbnailRequested()) { registerCompressedImage(tag.getValueAt(0)); } break; case ExifTag.TAG_JPEG_INTERCHANGE_FORMAT_LENGTH: if (isThumbnailRequested()) { mJpegSizeTag = tag; } break; case ExifTag.TAG_STRIP_OFFSETS: if (isThumbnailRequested()) { if (tag.hasValue()) { for (int i = 0; i < tag.getComponentCount(); i++) { if (tag.getDataType() == ExifTag.TYPE_UNSIGNED_SHORT) { registerUncompressedStrip(i, tag.getValueAt(i)); } else { registerUncompressedStrip(i, tag.getValueAt(i)); } } } else { mCorrespondingEvent.put(tag.getOffset(), new ExifTagEvent(tag, false)); } } break; case ExifTag.TAG_STRIP_BYTE_COUNTS: if (isThumbnailRequested()) { if (tag.hasValue()) { mStripSizeTag = tag; } } break; } } void readFullTagValue(ExifTag tag) throws IOException { // Some invalid images contains tags with wrong size, check it here short type = tag.getDataType(); if (type == ExifTag.TYPE_ASCII || type == ExifTag.TYPE_UNDEFINED || type == ExifTag.TYPE_UNSIGNED_BYTE) { int size = tag.getComponentCount(); if (mCorrespondingEvent.size() > 0) { if (mCorrespondingEvent.firstEntry().getKey() < mTiffStream.getReadByteCount() + size) { Log.w(TAG, "Invalid size of tag."); size = mCorrespondingEvent.firstEntry().getKey() - mTiffStream.getReadByteCount(); tag.setComponentCount(size); } } } switch(tag.getDataType()) { case ExifTag.TYPE_UNSIGNED_BYTE: case ExifTag.TYPE_UNDEFINED: { byte buf[] = new byte[tag.getComponentCount()]; read(buf); tag.setValue(buf); } break; case ExifTag.TYPE_ASCII: tag.setValue(readString(tag.getComponentCount())); break; case ExifTag.TYPE_UNSIGNED_LONG: { long value[] = new long[tag.getComponentCount()]; for (int i = 0, n = value.length; i < n; i++) { value[i] = readUnsignedLong(); } tag.setValue(value); } break; case ExifTag.TYPE_UNSIGNED_RATIONAL: { Rational value[] = new Rational[tag.getComponentCount()]; for (int i = 0, n = value.length; i < n; i++) { value[i] = readUnsignedRational(); } tag.setValue(value); } break; case ExifTag.TYPE_UNSIGNED_SHORT: { int value[] = new int[tag.getComponentCount()]; for (int i = 0, n = value.length; i < n; i++) { value[i] = readUnsignedShort(); } tag.setValue(value); } break; case ExifTag.TYPE_LONG: { int value[] = new int[tag.getComponentCount()]; for (int i = 0, n = value.length; i < n; i++) { value[i] = readLong(); } tag.setValue(value); } break; case ExifTag.TYPE_RATIONAL: { Rational value[] = new Rational[tag.getComponentCount()]; for (int i = 0, n = value.length; i < n; i++) { value[i] = readRational(); } tag.setValue(value); } break; } } private void parseTiffHeader() throws IOException, ExifInvalidFormatException { short byteOrder = mTiffStream.readShort(); ByteOrder order; if (LITTLE_ENDIAN_TAG == byteOrder) { mTiffStream.setByteOrder(ByteOrder.LITTLE_ENDIAN); } else if (BIG_ENDIAN_TAG == byteOrder) { mTiffStream.setByteOrder(ByteOrder.BIG_ENDIAN); } else { throw new ExifInvalidFormatException("Invalid TIFF header"); } if (mTiffStream.readShort() != TIFF_HEADER_TAIL) { throw new ExifInvalidFormatException("Invalid TIFF header"); } } private boolean seekTiffData(InputStream inputStream) throws IOException, ExifInvalidFormatException { DataInputStream dataStream = new DataInputStream(inputStream); if (dataStream.readShort() != JpegHeader.SOI) { throw new ExifInvalidFormatException("Invalid JPEG format"); } short marker = dataStream.readShort(); while(marker != JpegHeader.EOI && !JpegHeader.isSofMarker(marker)) { int length = dataStream.readUnsignedShort(); // Some invalid formatted image contains multiple APP1, // try to find the one with Exif data. if (marker == JpegHeader.APP1) { int header = 0; short headerTail = 0; if (length >= 8) { header = dataStream.readInt(); headerTail = dataStream.readShort(); length -= 6; if (header == EXIF_HEADER && headerTail == EXIF_HEADER_TAIL) { mApp1End = length; return true; } } } if (length < 2 || (length - 2) != dataStream.skip(length - 2)) { Log.w(TAG, "Invalid JPEG format."); return false; } marker = dataStream.readShort(); } return false; } /** * Reads bytes from the InputStream. */ public int read(byte[] buffer, int offset, int length) throws IOException { return mTiffStream.read(buffer, offset, length); } /** * Equivalent to read(buffer, 0, buffer.length). */ public int read(byte[] buffer) throws IOException { return mTiffStream.read(buffer); } /** * Reads a String from the InputStream with US-ASCII charset. * The parser will read n bytes and convert it to ascii string. * This is used for reading values of type {@link ExifTag#TYPE_ASCII}. */ public String readString(int n) throws IOException { return readString(n, US_ASCII); } /** * Reads a String from the InputStream with the given charset. * The parser will read n bytes and convert it to string. * This is used for reading values of type {@link ExifTag#TYPE_ASCII}. */ public String readString(int n, Charset charset) throws IOException { if (n > 0) { byte[] buf = new byte[n]; return mTiffStream.readString(n, charset); } else { return ""; } } /** * Reads value of type {@link ExifTag#TYPE_UNSIGNED_SHORT} from the InputStream. */ public int readUnsignedShort() throws IOException { return mTiffStream.readShort() & 0xffff; } /** * Reads value of type {@link ExifTag#TYPE_UNSIGNED_LONG} from the InputStream. */ public long readUnsignedLong() throws IOException { return readLong() & 0xffffffffL; } /** * Reads value of type {@link ExifTag#TYPE_UNSIGNED_RATIONAL} from the InputStream. */ public Rational readUnsignedRational() throws IOException { long nomi = readUnsignedLong(); long denomi = readUnsignedLong(); return new Rational(nomi, denomi); } /** * Reads value of type {@link ExifTag#TYPE_LONG} from the InputStream. */ public int readLong() throws IOException { return mTiffStream.readInt(); } /** * Reads value of type {@link ExifTag#TYPE_RATIONAL} from the InputStream. */ public Rational readRational() throws IOException { int nomi = readLong(); int denomi = readLong(); return new Rational(nomi, denomi); } private static class ImageEvent { int stripIndex; int type; ImageEvent(int type) { this.stripIndex = 0; this.type = type; } ImageEvent(int type, int stripIndex) { this.type = type; this.stripIndex = stripIndex; } } private static class IfdEvent { int ifd; boolean isRequested; IfdEvent(int ifd, boolean isInterestedIfd) { this.ifd = ifd; this.isRequested = isInterestedIfd; } } private static class ExifTagEvent { ExifTag tag; boolean isRequested; ExifTagEvent(ExifTag tag, boolean isRequireByUser) { this.tag = tag; this.isRequested = isRequireByUser; } } /** * Gets the byte order of the current InputStream. */ public ByteOrder getByteOrder() { return mTiffStream.getByteOrder(); } }