    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}