/*
* 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.COSBase;
import org.apache.pdfbox.pdmodel.common.PDRange;
import org.apache.pdfbox.pdmodel.common.function.type4.ExecutionContext;
import org.apache.pdfbox.pdmodel.common.function.type4.InstructionSequence;
import org.apache.pdfbox.pdmodel.common.function.type4.InstructionSequenceBuilder;
import org.apache.pdfbox.pdmodel.common.function.type4.Operators;
import java.io.IOException;
/**
* This class represents a Type 4 (PostScript calculator) function in a PDF document.
* <p>
* See section 3.9.4 of the PDF 1.4 Reference.
*
* @version $Revision: 1.2 $
*/
public class PDFunctionType4 extends PDFunction
{
private static final Operators OPERATORS = new Operators();
private final InstructionSequence instructions;
/**
* Constructor.
*
* @param functionStream The function stream.
* @throws IOException if an I/O error occurs while reading the function
*/
public PDFunctionType4(COSBase functionStream) throws IOException
{
super( functionStream );
this.instructions = InstructionSequenceBuilder.parse(
getPDStream().getInputStreamAsString());
}
/**
* {@inheritDoc}
*/
public int getFunctionType()
{
return 4;
}
/**
* {@inheritDoc}
*/
public float[] eval(float[] input) throws IOException
{
//Setup the input values
ExecutionContext context = new ExecutionContext(OPERATORS);
for (int i = 0; i < input.length; i++)
{
PDRange domain = getDomainForInput(i);
float value = clipToRange(input[i], domain.getMin(), domain.getMax());
context.getStack().push(value);
}
//Execute the type 4 function.
instructions.execute(context);
//Extract the output values
int numberOfOutputValues = getNumberOfOutputParameters();
int numberOfActualOutputValues = context.getStack().size();
if (numberOfActualOutputValues < numberOfOutputValues)
{
throw new IllegalStateException("The type 4 function returned "
+ numberOfActualOutputValues
+ " values but the Range entry indicates that "
+ numberOfOutputValues + " values be returned.");
}
float[] outputValues = new float[numberOfOutputValues];
for (int i = numberOfOutputValues - 1; i >= 0; i--)
{
PDRange range = getRangeForOutput(i);
outputValues[i] = context.popReal();
outputValues[i] = clipToRange(outputValues[i], range.getMin(), range.getMax());
}
//Return the resulting array
return outputValues;
}
}