001/*
002 *  Licensed under the Apache License, Version 2.0 (the "License");
003 *  you may not use this file except in compliance with the License.
004 *  You may obtain a copy of the License at
005 *
006 *       http://www.apache.org/licenses/LICENSE-2.0
007 *
008 *  Unless required by applicable law or agreed to in writing, software
009 *  distributed under the License is distributed on an "AS IS" BASIS,
010 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
011 *  See the License for the specific language governing permissions and
012 *  limitations under the License.
013 *  under the License.
014 */
015
016package org.apache.commons.imaging.formats.jpeg.segments;
017
018import static org.apache.commons.imaging.common.BinaryFunctions.read2Bytes;
019import static org.apache.commons.imaging.common.BinaryFunctions.readByte;
020
021import java.io.ByteArrayInputStream;
022import java.io.IOException;
023import java.io.InputStream;
024import java.util.ArrayList;
025import java.util.List;
026
027import org.apache.commons.imaging.ImagingException;
028
029public final class DqtSegment extends AbstractSegment {
030    public static class QuantizationTable {
031        public final int precision;
032        public final int destinationIdentifier;
033        private final int[] elements;
034
035        public QuantizationTable(final int precision, final int destinationIdentifier, final int[] elements) {
036            this.precision = precision;
037            this.destinationIdentifier = destinationIdentifier;
038            this.elements = elements;
039        }
040
041        /**
042         * @return the elements
043         */
044        public int[] getElements() {
045            return elements;
046        }
047    }
048
049    public final List<QuantizationTable> quantizationTables = new ArrayList<>();
050
051    public DqtSegment(final int marker, final byte[] segmentData) throws ImagingException, IOException {
052        this(marker, segmentData.length, new ByteArrayInputStream(segmentData));
053    }
054
055    public DqtSegment(final int marker, int length, final InputStream is) throws ImagingException, IOException {
056        super(marker, length);
057
058        while (length > 0) {
059            final int precisionAndDestination = readByte("QuantizationTablePrecisionAndDestination", is, "Not a Valid JPEG File");
060            length--;
061            final int precision = precisionAndDestination >> 4 & 0xf;
062            final int destinationIdentifier = precisionAndDestination & 0xf;
063
064            final int[] elements = new int[64];
065            for (int i = 0; i < 64; i++) {
066                if (precision == 0) {
067                    elements[i] = 0xff & readByte("QuantizationTableElement", is, "Not a Valid JPEG File");
068                    length--;
069                } else if (precision == 1) {
070                    elements[i] = read2Bytes("QuantizationTableElement", is, "Not a Valid JPEG File", getByteOrder());
071                    length -= 2;
072                } else {
073                    throw new ImagingException("Quantization table precision '" + precision + "' is invalid");
074                }
075            }
076
077            quantizationTables.add(new QuantizationTable(precision, destinationIdentifier, elements));
078        }
079    }
080
081    @Override
082    public String getDescription() {
083        return "DQT (" + getSegmentType() + ")";
084    }
085}