001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.imaging.palette;
018
019import java.util.List;
020import org.apache.commons.imaging.ImageWriteException;
021
022public class QuantizedPalette implements Palette {
023    private final int precision;
024    private final List<ColorSpaceSubset> subsets;
025    private final ColorSpaceSubset[] straight;
026
027    public QuantizedPalette(final List<ColorSpaceSubset> subsets, final int precision) {
028        this.subsets = subsets;
029        this.precision = precision;
030
031        straight = new ColorSpaceSubset[1 << (precision * 3)];
032
033        for (int i = 0; i < subsets.size(); i++) {
034            final ColorSpaceSubset subset = subsets.get(i);
035            subset.setIndex(i);
036
037            for (int u = subset.mins[0]; u <= subset.maxs[0]; u++) {
038                for (int j = subset.mins[1]; j <= subset.maxs[1]; j++) {
039                    for (int k = subset.mins[2]; k <= subset.maxs[2]; k++) {
040                        final int index = (u << (precision * 2))
041                                | (j << (precision * 1))
042                                | (k << (precision * 0));
043                        straight[index] = subset;
044                    }
045                }
046            }
047        }
048    }
049
050    @Override
051    public int getPaletteIndex(final int rgb) throws ImageWriteException {
052        final int precisionMask = (1 << precision) - 1;
053
054        final int index = ((rgb >> (24 - 3 * precision)) & (precisionMask << (precision << 1)))
055                | ((rgb >> (16 - 2 * precision)) & (precisionMask << precision))
056                | ((rgb >> (8 - precision)) & (precisionMask));
057
058        return straight[index].getIndex();
059    }
060
061    @Override
062    public int getEntry(final int index) {
063        final ColorSpaceSubset subset = subsets.get(index);
064        return subset.rgb;
065    }
066
067    @Override
068    public int length() {
069        return subsets.size();
070    }
071}