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.Comparator;
020import java.util.Objects;
021
022/**
023 * A comparator for {#link ColorCount} elements.
024 *
025 * <p>
026 * It uses a given {#link ColorComponent} to choose what channel must be used for the comparison.
027 * </p>
028 *
029 * <p>
030 * For example, if the comparator is created for the {@link ColorComponent#RED} channel, then it will compare the value of red of each {@code ColorCount} object
031 * in the array of elements.
032 * </p>
033 *
034 * @since 1.0-alpha2
035 */
036public class ColorCountComparator implements Comparator<ColorCount> {
037
038    /**
039     * Color component used during the comparison.
040     */
041    private final ColorComponent colorComponent;
042
043    /**
044     * Constructs a new instance.
045     *
046     * @param colorComponent Color component to wrap.
047     */
048    public ColorCountComparator(final ColorComponent colorComponent) {
049        this.colorComponent = Objects.requireNonNull(colorComponent, "colorComponent");
050    }
051
052    @Override
053    public int compare(final ColorCount c1, final ColorCount c2) {
054        switch (colorComponent) {
055        case ALPHA:
056            return c1.alpha - c2.alpha;
057        case RED:
058            return c1.red - c2.red;
059        case GREEN:
060            return c1.green - c2.green;
061        case BLUE:
062            return c1.blue - c2.blue;
063        default:
064            return 0;
065        }
066    }
067
068}