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.Collections;
020import java.util.List;
021
022import org.apache.commons.imaging.ImagingException;
023import org.apache.commons.imaging.common.Allocator;
024
025public class QuantizedPalette implements Palette {
026
027    private final int precision;
028    private final List<ColorSpaceSubset> subsets;
029    private final ColorSpaceSubset[] straight;
030
031    public QuantizedPalette(final List<ColorSpaceSubset> subsets, final int precision) {
032        this.subsets = subsets == null ? Collections.emptyList() : Collections.unmodifiableList(subsets);
033        this.precision = precision;
034
035        straight = Allocator.array(1 << precision * 3, ColorSpaceSubset[]::new, ColorSpaceSubset.SHALLOW_SIZE);
036
037        for (int i = 0; i < this.subsets.size(); i++) {
038            final ColorSpaceSubset subset = this.subsets.get(i);
039            subset.setIndex(i);
040
041            for (int u = subset.mins[0]; u <= subset.maxs[0]; u++) {
042                for (int j = subset.mins[1]; j <= subset.maxs[1]; j++) {
043                    for (int k = subset.mins[2]; k <= subset.maxs[2]; k++) {
044                        final int index = u << precision * 2 | j << precision * 1 | k << precision * 0;
045                        straight[index] = subset;
046                    }
047                }
048            }
049        }
050    }
051
052    @Override
053    public int getEntry(final int index) {
054        final ColorSpaceSubset subset = subsets.get(index);
055        return subset.rgb;
056    }
057
058    @Override
059    public int getPaletteIndex(final int rgb) throws ImagingException {
060        final int precisionMask = (1 << precision) - 1;
061
062        final int index = rgb >> 24 - 3 * precision & precisionMask << (precision << 1) | rgb >> 16 - 2 * precision & precisionMask << precision
063                | rgb >> 8 - precision & precisionMask;
064
065        return straight[index].getIndex();
066    }
067
068    @Override
069    public int length() {
070        return subsets.size();
071    }
072}