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 org.apache.commons.imaging.ImageWriteException;
020
021/**
022 * Color palette.
023 */
024public interface Palette {
025
026    // TODO: shouldn't it be an ImageReadException for getPaletteIndex?
027    /**
028     * Looks up the palette index for a given color.
029     * @param rgb the color to look up
030     * @return the palette index
031     * @throws ImageWriteException if it fails to read the palette index
032     */
033    int getPaletteIndex(int rgb) throws ImageWriteException;
034
035    /**
036     * Looks up the color for a given palette index.
037     * @param index the palette index to look up
038     * @return the color in ARGB format
039     */
040    int getEntry(int index);
041
042    /**
043     * The number of entries in the palette.
044     * @return the number of palette entries
045     */
046    int length();
047
048}