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.ImageReadException;
028
029public class DqtSegment extends Segment {
030    public final List<QuantizationTable> quantizationTables = new ArrayList<>();
031
032    public static class QuantizationTable {
033        public final int precision;
034        public final int destinationIdentifier;
035        private final int[] elements;
036
037        public QuantizationTable(final int precision, final int destinationIdentifier,
038                final int[] elements) {
039            this.precision = precision;
040            this.destinationIdentifier = destinationIdentifier;
041            this.elements = elements;
042        }
043
044        /**
045         * @return the elements
046         */
047        public int[] getElements() {
048            return elements;
049        }
050    }
051
052    public DqtSegment(final int marker, final byte[] segmentData)
053            throws ImageReadException, IOException {
054        this(marker, segmentData.length, new ByteArrayInputStream(segmentData));
055    }
056
057    public DqtSegment(final int marker, int length, final InputStream is)
058            throws ImageReadException, IOException {
059        super(marker, length);
060
061        while (length > 0) {
062            final int precisionAndDestination = readByte(
063                    "QuantizationTablePrecisionAndDestination", is,
064                    "Not a Valid JPEG File");
065            length--;
066            final int precision = (precisionAndDestination >> 4) & 0xf;
067            final int destinationIdentifier = precisionAndDestination & 0xf;
068
069            final int[] elements = new int[64];
070            for (int i = 0; i < 64; i++) {
071                if (precision == 0) {
072                    elements[i] = 0xff & readByte("QuantizationTableElement",
073                            is, "Not a Valid JPEG File");
074                    length--;
075                } else if (precision == 1) {
076                    elements[i] = read2Bytes("QuantizationTableElement", is, "Not a Valid JPEG File", getByteOrder());
077                    length -= 2;
078                } else {
079                    throw new ImageReadException(
080                            "Quantization table precision '" + precision
081                                    + "' is invalid");
082                }
083            }
084
085            quantizationTables.add(new QuantizationTable(precision,
086                    destinationIdentifier, elements));
087        }
088    }
089
090    @Override
091    public String getDescription() {
092        return "DQT (" + getSegmentType() + ")";
093    }
094}