/*
* Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
* Santa Clara, California 95054, U.S.A. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.sun.pdfview.function;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.*;
import com.sun.pdfview.PDFObject;
import com.sun.pdfview.function.postscript.PostScriptParser;
import com.sun.pdfview.function.postscript.operation.OperationSet;
import com.sun.pdfview.function.postscript.operation.PostScriptOperation;
/**
* <p>A PostScript function is represented as a stream containing code
* written in a small subset of the PostScript language.
* This reference is taken from the (3200-1:2008:7.10.5)<p>
*
* http://www.adobe.com/devnet/acrobat/pdfs/adobe_supplement_iso32000.pdf
* </p>
*/
public class FunctionType4 extends PDFFunction {
/** the list of tokens and sub-expressions. */
private List<String> tokens;
/** the stack of operations. The stack contents should all be Comparable. */
private Stack<Object> stack;
/** Creates a new instance of FunctionType4 */
protected FunctionType4() {
super(TYPE_4);
}
/** Read the function information from a PDF Object */
@Override
protected void parse(PDFObject obj) throws IOException {
ByteBuffer buf = obj.getStreamBuffer();
byte[] byteA = new byte[buf.remaining()];
buf.get(byteA);
String scriptContent = new String(byteA, "UTF-8");
this.tokens = new PostScriptParser().parse(scriptContent);
}
/**
* Map from <i>m</i> input values to <i>n</i> output values.
* The number of inputs <i>m</i> must be exactly one half the size of the
* domain. The number of outputs should match one half the size of the
* range.
*
* @param inputs an array of <i>m</i> input values
* @param inputOffset the offset into the input array to read from
* @param outputs an array of size >= <i>n</i> which will be filled
* with the output values
* @param outputOffset the offset into the output array to write to
*/
@Override
protected void doFunction(float[] inputs, int inputOffset, float[] outputs, int outputOffset) {
prepareInitialStack(inputs, inputOffset);
for (Iterator<String> iterator = this.tokens.iterator(); iterator.hasNext(); ) {
String token = iterator.next();
PostScriptOperation op = OperationSet.getInstance().getOperation(token);
op.eval(this.stack);
}
assertResultIsCorrect(outputs, outputOffset);
prepareResult(outputs, outputOffset);
}
/*************************************************************************
* @param outputs
* @param outputOffset
************************************************************************/
private void prepareResult(float[] outputs, int outputOffset) {
for (int i = outputOffset; i < outputs.length; i++) {
outputs[outputs.length-i-1] = ((Double)this.stack.pop()).floatValue();
}
}
/*************************************************************************
* Put all input values on the initial stack.
* All values are pushed as Double because we calculate internally with double.
* @param inputs
* @param inputOffset
************************************************************************/
private void prepareInitialStack(float[] inputs, int inputOffset) {
this.stack = new Stack<Object>();
for (int i = inputOffset; i < inputs.length; i++) {
this.stack.push(new Double(inputs[i]));
}
}
/*************************************************************************
* @param outputs
* @param outputOffset
************************************************************************/
private void assertResultIsCorrect(float[] outputs, int outputOffset) {
int expectedResults = outputs.length-outputOffset;
if (this.stack.size() != expectedResults) {
throw new IllegalStateException("Output does not match result "+expectedResults+"/"+this.stack);
}
}
}