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- /*
- * 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.
- */
-
- /* $Id$ */
-
- package org.apache.fop.pdf;
-
- import java.io.OutputStream;
- import java.lang.ref.Reference;
- import java.lang.ref.SoftReference;
-
- /**
- * Class representing a PDF object reference. The object holds a soft reference to the actual
- * PDF object so the garbage collector can free the object if it's not referenced elsewhere. The
- * important thing about the class is the reference information to the actual PDF object in the
- * PDF file.
- */
- public class PDFReference implements PDFWritable {
-
- private PDFObjectNumber objectNumber;
- private int generation;
-
- private Reference<PDFObject> objReference;
-
- /**
- * Creates a new PDF reference.
- * @param obj the object to be referenced
- */
- public PDFReference(PDFObject obj) {
- this.objectNumber = obj.getObjectNumber();
- this.generation = obj.getGeneration();
- this.objReference = new SoftReference<PDFObject>(obj);
- }
-
- /**
- * Creates a new PDF reference, but without a reference to the original object.
- * @param ref an object reference
- */
- public PDFReference(String ref) {
- if (ref == null) {
- throw new NullPointerException("ref must not be null");
- }
- String[] parts = ref.split(" ");
- assert parts.length == 3;
- this.objectNumber = new PDFObjectNumber(Integer.parseInt(parts[0]));
- this.generation = Integer.parseInt(parts[1]);
- assert "R".equals(parts[2]);
- }
-
- /**
- * Returns the PDF object
- * @return the PDF object, or null if it has been released
- */
- public PDFObject getObject() {
- if (this.objReference != null) {
- PDFObject obj = this.objReference.get();
- if (obj == null) {
- this.objReference = null;
- }
- return obj;
- } else {
- return null;
- }
- }
-
- /**
- * Returns the object number.
- * @return the object number
- */
- public PDFObjectNumber getObjectNumber() {
- return this.objectNumber;
- }
-
- /**
- * Returns the generation.
- * @return the generation
- */
- public int getGeneration() {
- return this.generation;
- }
-
- /** {@inheritDoc} */
- @Override
- public String toString() {
- StringBuilder textBuffer = new StringBuilder();
- outputInline(null, textBuffer);
- return textBuffer.toString();
- }
-
- /** {@inheritDoc} */
- public void outputInline(OutputStream out, StringBuilder textBuffer) {
- textBuffer.append(getObjectNumber().getNumber()).append(' ').append(getGeneration()).append(" R");
- }
-
- }
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