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.formats.png.transparencyfilters;
018
019import java.io.IOException;
020
021import org.apache.commons.imaging.ImagingException;
022
023public class TransparencyFilterIndexedColor extends AbstractTransparencyFilter {
024
025    public TransparencyFilterIndexedColor(final byte[] bytes) {
026        super(bytes);
027    }
028
029    @Override
030    public int filter(final int rgb, final int index) throws ImagingException, IOException {
031        final int length = getLength();
032        if (index >= length) { // TODO see below - is this check correct?
033            return rgb;
034        }
035
036        if (index < 0 || index > length) { // TODO check for > length cannot be true because of check above
037            throw new ImagingException("TransparencyFilterIndexedColor index: " + index + ", bytes.length: " + length);
038        }
039
040        final int alpha = getByte(index);
041        return (0xff & alpha) << 24 | 0x00ffffff & rgb;
042    }
043}