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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.imaging.palette;
18  
19  import org.apache.commons.imaging.ImageWriteException;
20  
21  /**
22   * Color palette.
23   */
24  public interface Palette {
25  
26      // TODO: shouldn't it be an ImageReadException for getPaletteIndex?
27      /**
28       * Looks up the palette index for a given color.
29       * @param rgb the color to look up
30       * @return the palette index
31       * @throws ImageWriteException if it fails to read the palette index
32       */
33      int getPaletteIndex(int rgb) throws ImageWriteException;
34  
35      /**
36       * Looks up the color for a given palette index.
37       * @param index the palette index to look up
38       * @return the color in ARGB format
39       */
40      int getEntry(int index);
41  
42      /**
43       * The number of entries in the palette.
44       * @return the number of palette entries
45       */
46      int length();
47  
48  }