org.apache.pdfbox.multipdf.PDFCloneUtility.java Source code

Java tutorial

Introduction

Here is the source code for org.apache.pdfbox.multipdf.PDFCloneUtility.java

Source

/*
 * 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.multipdf;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSBase;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSObject;
import org.apache.pdfbox.cos.COSStream;
import org.apache.pdfbox.io.IOUtils;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.common.COSObjectable;

/**
 * Utility class used to clone PDF objects. It keeps track of objects it has
 * already cloned.
 *
 */
class PDFCloneUtility {
    private final PDDocument destination;
    private final Map<Object, COSBase> clonedVersion = new HashMap<>();
    private final Set<COSBase> clonedValues = new HashSet<>();
    // It might be useful to use IdentityHashMap like in PDFBOX-4477 for speed,
    // but we need a really huge file to test this. A test with the file from PDFBOX-4477
    // did not show a noticeable speed difference.

    /**
     * Creates a new instance for the given target document.
     * @param dest the destination PDF document that will receive the clones
     */
    PDFCloneUtility(PDDocument dest) {
        this.destination = dest;
    }

    /**
     * Returns the destination PDF document this cloner instance is set up for.
     * @return the destination PDF document
     */
    PDDocument getDestination() {
        return this.destination;
    }

    /**
     * Deep-clones the given object for inclusion into a different PDF document identified by
     * the destination parameter.
     * @param base the initial object as the root of the deep-clone operation
     * @return the cloned instance of the base object
     * @throws IOException if an I/O error occurs
     */
    COSBase cloneForNewDocument(Object base) throws IOException {
        if (base == null) {
            return null;
        }
        COSBase retval = clonedVersion.get(base);
        if (retval != null) {
            //we are done, it has already been converted.
            return retval;
        }
        if (base instanceof COSBase && clonedValues.contains(base)) {
            // Don't clone a clone
            return (COSBase) base;
        }
        if (base instanceof List) {
            COSArray array = new COSArray();
            List<?> list = (List<?>) base;
            for (Object obj : list) {
                array.add(cloneForNewDocument(obj));
            }
            retval = array;
        } else if (base instanceof COSObjectable && !(base instanceof COSBase)) {
            retval = cloneForNewDocument(((COSObjectable) base).getCOSObject());
        } else if (base instanceof COSObject) {
            COSObject object = (COSObject) base;
            retval = cloneForNewDocument(object.getObject());
        } else if (base instanceof COSArray) {
            COSArray newArray = new COSArray();
            COSArray array = (COSArray) base;
            for (int i = 0; i < array.size(); i++) {
                newArray.add(cloneForNewDocument(array.get(i)));
            }
            retval = newArray;
        } else if (base instanceof COSStream) {
            COSStream originalStream = (COSStream) base;
            COSStream stream = destination.getDocument().createCOSStream();
            try (OutputStream output = stream.createRawOutputStream();
                    InputStream input = originalStream.createRawInputStream()) {
                IOUtils.copy(input, output);
            }
            clonedVersion.put(base, stream);
            for (Map.Entry<COSName, COSBase> entry : originalStream.entrySet()) {
                stream.setItem(entry.getKey(), cloneForNewDocument(entry.getValue()));
            }
            retval = stream;
        } else if (base instanceof COSDictionary) {
            COSDictionary dic = (COSDictionary) base;
            retval = new COSDictionary();
            clonedVersion.put(base, retval);
            for (Map.Entry<COSName, COSBase> entry : dic.entrySet()) {
                ((COSDictionary) retval).setItem(entry.getKey(), cloneForNewDocument(entry.getValue()));
            }
        } else {
            retval = (COSBase) base;
        }
        clonedVersion.put(base, retval);
        clonedValues.add(retval);
        return retval;
    }

    /**
     * Merges two objects of the same type by deep-cloning its members.
     * <br>
     * Base and target must be instances of the same class.
     * @param base the base object to be cloned
     * @param target the merge target
     * @throws IOException if an I/O error occurs
     */
    void cloneMerge(final COSObjectable base, COSObjectable target) throws IOException {
        if (base == null) {
            return;
        }
        COSBase retval = clonedVersion.get(base);
        if (retval != null) {
            return;
            //we are done, it has already been converted. // ### Is that correct for cloneMerge???
        }
        //TODO what when clone-merging a clone? Does it ever happen?
        if (!(base instanceof COSBase)) {
            cloneMerge(base.getCOSObject(), target.getCOSObject());
        } else if (base instanceof COSObject) {
            if (target instanceof COSObject) {
                cloneMerge(((COSObject) base).getObject(), ((COSObject) target).getObject());
            } else if (target instanceof COSDictionary || target instanceof COSArray) {
                cloneMerge(((COSObject) base).getObject(), target);
            }
        } else if (base instanceof COSArray) {
            COSArray array = (COSArray) base;
            for (int i = 0; i < array.size(); i++) {
                ((COSArray) target).add(cloneForNewDocument(array.get(i)));
            }
        } else if (base instanceof COSStream) {
            // does that make sense???
            COSStream originalStream = (COSStream) base;
            COSStream stream = destination.getDocument().createCOSStream();
            try (OutputStream output = stream.createOutputStream(originalStream.getFilters())) {
                IOUtils.copy(originalStream.createInputStream(), output);
            }
            clonedVersion.put(base, stream);
            for (Map.Entry<COSName, COSBase> entry : originalStream.entrySet()) {
                stream.setItem(entry.getKey(), cloneForNewDocument(entry.getValue()));
            }
            retval = stream;
        } else if (base instanceof COSDictionary) {
            COSDictionary dic = (COSDictionary) base;
            clonedVersion.put(base, retval);
            for (Map.Entry<COSName, COSBase> entry : dic.entrySet()) {
                COSName key = entry.getKey();
                COSBase value = entry.getValue();
                if (((COSDictionary) target).getItem(key) != null) {
                    cloneMerge(value, ((COSDictionary) target).getItem(key));
                } else {
                    ((COSDictionary) target).setItem(key, cloneForNewDocument(value));
                }
            }
        } else {
            retval = (COSBase) base;
        }
        clonedVersion.put(base, retval);
        clonedValues.add(retval);
    }
}