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The Apache PDFBox library is an open source Java tool for working with PDF documents.

There is a newer version: 3.0.2

/*
 * 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.pdfbox.pdmodel.common.function;

import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSBase;
import org.apache.pdfbox.cos.COSFloat;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSNumber;
import java.io.IOException;

/**
 * This class represents a type 2 function in a PDF document.
 *
 * @author Ben Litchfield
 * @version $Revision: 1.2 $
 */
public class PDFunctionType2 extends PDFunction
{
    
    /**
     * The C0 values of the exponential function.
     */
    private COSArray C0;
    /**
     * The C1 values of the exponential function.
     */
    private COSArray C1;
    /**
     * The N value of the exponential function.
     */
    private Float N;

    /**
     * Constructor.
     *
     * @param function The function.
     */
    public PDFunctionType2(COSBase function)
    {
        super( function );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int getFunctionType()
    {
        return 2;
    }

    /**
    * {@inheritDoc}
    */
    @Override
    public float[] eval(float[] input) throws IOException
    {
        //This function performs exponential interpolation.
        //It uses only a single value as its input, but may produce a multi-valued output.
        //See PDF Reference section 3.9.2.
                
        double inputValue = input[0];
        double exponent = getN();
        COSArray c0 = getC0();
        COSArray c1 = getC1();
        int c0Size = c0.size();
        float[] functionResult = new float[c0Size];
        for (int j=0;j