com.lowagie.rups.model.IndirectObjectFactory Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of pdf-swing Show documentation
There is a newer version: 2.2.2
/*
 * $Id: IndirectObjectFactory.java 3117 2008-01-31 05:53:22Z xlv $
 *
 * Copyright 2007 Bruno Lowagie.
 *
 * 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.lowagie.rups.model;

import com.lowagie.text.pdf.IntHashtable;
import com.lowagie.text.pdf.PdfDictionary;
import com.lowagie.text.pdf.PdfName;
import com.lowagie.text.pdf.PdfNull;
import com.lowagie.text.pdf.PdfObject;
import com.lowagie.text.pdf.PdfReader;
import java.util.ArrayList;

/**
 * A factory that can produce all the indirect objects in a PDF file.
 */
public class IndirectObjectFactory {

    /**
     * The reader object.
     */
    protected PdfReader reader;
    /**
     * The current xref number.
     */
    protected int current;
    /**
     * The highest xref number.
     */
    protected int n;
    /**
     * A list of all the indirect objects in a PDF file.
     */
    protected ArrayList objects = new ArrayList<>();
    /**
     * Mapping between the index in the objects list and the reference number in the xref table.
     */
    protected IntHashtable idxToRef = new IntHashtable();
    /**
     * Mapping between the reference number in the xref table and the index in the objects list .
     */
    protected IntHashtable refToIdx = new IntHashtable();

    /**
     * Creates a list that will contain all the indirect objects in a PDF document.
     *
     * @param reader the reader that will read the PDF document
     */
    public IndirectObjectFactory(PdfReader reader) {
        this.reader = reader;
        current = -1;
        n = reader.getXrefSize();
    }

    /**
     * Gets the last object that has been registered. This method only makes sense while loading the factory. with
     * loadNextObject().
     *
     * @return the number of the last object that was stored
     */
    public int getCurrent() {
        return current;
    }

    /**
     * Gets the highest possible object number in the XRef table.
     *
     * @return an object number
     */
    public int getXRefMaximum() {
        return n;
    }

    /**
     * Stores the next object of the XRef table. As soon as this method returns false, it makes no longer sense calling
     * it as all the objects have been stored.
     *
     * @return false if there are no objects left to check.
     */
    public boolean storeNextObject() {
        while (current < n) {
            current++;
            PdfObject object = reader.getPdfObjectRelease(current);
            if (object != null) {
                int idx = size();
                idxToRef.put(idx, current);
                refToIdx.put(current, idx);
                store(object);
                return true;
            }
        }
        return false;
    }

    /**
     * If we store all the objects, we might run out of memory; that's why we'll only store the objects that are
     * necessary to construct other objects (for instance the page table).
     *
     * @param object an object we might want to store
     */
    private void store(PdfObject object) {
        if (object.isDictionary()) {
            PdfDictionary dict = (PdfDictionary) object;
            if (PdfName.PAGE.equals(dict.get(PdfName.TYPE))) {
                objects.add(dict);
                return;
            }
        }
        objects.add(PdfNull.PDFNULL);
    }

    /**
     * Gets the total number of indirect objects in the PDF file. This isn't necessarily the same number as returned by
     * getXRefMaximum(). The PDF specification allows gaps between object numbers.
     *
     * @return the total number of indirect objects in the PDF.
     */
    public int size() {
        return objects.size();
    }

    /**
     * Gets the index of an object based on its number in the xref table.
     *
     * @param ref a number in the xref table
     * @return the index in the list of indirect objects
     */
    public int getIndexByRef(int ref) {
        return refToIdx.get(ref);
    }

    /**
     * Gets the reference number in the xref table based on the index in the indirect object list.
     *
     * @param i the index of an object in the indirect object list
     * @return the corresponding reference number in the xref table
     */
    public int getRefByIndex(int i) {
        return idxToRef.get(i);
    }

    /**
     * Gets an object based on its index in the indirect object list.
     *
     * @param i an index in the indirect object list
     * @return a PDF object
     */
    public PdfObject getObjectByIndex(int i) {
        return getObjectByReference(getRefByIndex(i));
    }

    /**
     * Gets an object based on its reference number in the xref table.
     *
     * @param ref a number in the xref table
     * @return a PDF object
     */
    public PdfObject getObjectByReference(int ref) {
        return objects.get(getIndexByRef(ref));
    }

    /**
     * Loads an object based on its reference number in the xref table.
     *
     * @param ref a reference number in the xref table.
     * @return a PDF object
     */
    public PdfObject loadObjectByReference(int ref) {
        PdfObject object = getObjectByReference(ref);
        if (object instanceof PdfNull) {
            int idx = getIndexByRef(ref);
            object = reader.getPdfObject(ref);
            objects.set(idx, object);
        }
        return object;
    }
}