/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.imaging.formats.transparencyfilters;

import java.io.ByteArrayInputStream;
import java.io.IOException;

import org.apache.commons.imaging.ImageReadException;

public class TransparencyFilterGrayscale extends TransparencyFilter
{
    private final int transparent_color;

    public TransparencyFilterGrayscale(byte bytes[]) throws ImageReadException,
            IOException
    {
        super(bytes);

        ByteArrayInputStream is = new ByteArrayInputStream(bytes);
        transparent_color = read2Bytes("transparent_color", is,
                "tRNS: Missing transparent_color");
    }

    @Override
    public int filter(int rgb, int index) throws ImageReadException,
            IOException
    {
        if (index != transparent_color)
            return rgb;
        return 0x00;
    }
}