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The Apache PDFBox library is an open source Java tool for working with PDF documents.
/*
* 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.COSName;
import org.apache.pdfbox.pdmodel.common.PDRange;
import java.io.IOException;
/**
* This class represents a Type 3 (stitching) function in a PDF document.
*
* @author Ben Litchfield
*/
public class PDFunctionType3 extends PDFunction
{
private COSArray functions = null;
private COSArray encode = null;
private COSArray bounds = null;
private PDFunction[] functionsArray = null;
private float[] boundsValues = null;
/**
* Constructor.
*
* @param functionStream The function .
*/
public PDFunctionType3(COSBase functionStream)
{
super( functionStream );
}
/**
* {@inheritDoc}
*/
@Override
public int getFunctionType()
{
return 3;
}
/**
* {@inheritDoc}
*/
@Override
public float[] eval(float[] input) throws IOException
{
//This function is known as a "stitching" function. Based on the input, it decides which child function to call.
// All functions in the array are 1-value-input functions
//See PDF Reference section 3.9.3.
PDFunction function = null;
float x = input[0];
PDRange domain = getDomainForInput(0);
// clip input value to domain
x = clipToRange(x, domain.getMin(), domain.getMax());
if (functionsArray == null)
{
COSArray ar = getFunctions();
functionsArray = new PDFunction[ar.size()];
for (int i = 0; i < ar.size(); ++i)
{
functionsArray[i] = PDFunction.create(ar.getObject(i));
}
}
if (functionsArray.length == 1)
{
// This doesn't make sense but it may happen ...
function = functionsArray[0];
PDRange encRange = getEncodeForParameter(0);
x = interpolate(x, domain.getMin(), domain.getMax(), encRange.getMin(), encRange.getMax());
}
else
{
if (boundsValues == null)
{
boundsValues = getBounds().toFloatArray();
}
int boundsSize = boundsValues.length;
// create a combined array containing the domain and the bounds values
// domain.min, bounds[0], bounds[1], ...., bounds[boundsSize-1], domain.max
float[] partitionValues = new float[boundsSize+2];
int partitionValuesSize = partitionValues.length;
partitionValues[0] = domain.getMin();
partitionValues[partitionValuesSize-1] = domain.getMax();
System.arraycopy(boundsValues, 0, partitionValues, 1, boundsSize);
// find the partition
for (int i=0; i < partitionValuesSize-1; i++)
{
if ( x >= partitionValues[i] &&
(x < partitionValues[i+1] || (i == partitionValuesSize - 2 && x == partitionValues[i+1])))
{
function = functionsArray[i];
PDRange encRange = getEncodeForParameter(i);
x = interpolate(x, partitionValues[i], partitionValues[i+1], encRange.getMin(), encRange.getMax());
break;
}
}
if (function == null)
{
throw new IOException("partition not found in type 3 function");
}
}
float[] functionValues = new float[]{x};
// calculate the output values using the chosen function
float[] functionResult = function.eval(functionValues);
// clip to range if available
return clipToRange(functionResult);
}
/**
* Returns all functions values as COSArray.
*
* @return the functions array.
*/
public COSArray getFunctions()
{
if (functions == null)
{
functions = (COSArray)(getCOSObject().getDictionaryObject( COSName.FUNCTIONS ));
}
return functions;
}
/**
* Returns all bounds values as COSArray.
*
* @return the bounds array.
*/
public COSArray getBounds()
{
if (bounds == null)
{
bounds = (COSArray)(getCOSObject().getDictionaryObject( COSName.BOUNDS ));
}
return bounds;
}
/**
* Returns all encode values as COSArray.
*
* @return the encode array.
*/
public COSArray getEncode()
{
if (encode == null)
{
encode = (COSArray)(getCOSObject().getDictionaryObject( COSName.ENCODE ));
}
return encode;
}
/**
* Get the encode for the input parameter.
*
* @param n The function parameter number.
*
* @return The encode parameter range or null if none is set.
*/
private PDRange getEncodeForParameter(int n)
{
COSArray encodeValues = getEncode();
return new PDRange( encodeValues, n );
}
}