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/*
 * $Id: PageLoader.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.sun.pdfview.PDFFile;
import com.sun.pdfview.PDFPage;

/**
 * Loads all the PDFPage objects for SUN's PDF Renderer in Background.
 */
public class PageLoader extends BackgroundTask {

    /**
     * The PDFFile (SUN's PDF Renderer class)
     */
    protected PDFFile file;
    /**
     * The total number of pages.
     */
    protected int numberOfPages;
    /**
     * True for pages with page number equal to index + 1 that are being loaded.
     */
    protected boolean[] busy;
    /**
     * True for pages with page number equal to index + 1 that have already been loaded.
     */
    protected boolean[] done;

    /**
     * Creates a new page loader.
     *
     * @param file the PDFFile (SUN's PDF Renderer)
     */
    public PageLoader(PDFFile file) {
        super();
        this.file = file;
        numberOfPages = file.getNumPages();
        busy = new boolean[numberOfPages];
        done = new boolean[numberOfPages];
        start();
    }

    /**
     * Getter for the number of pages.
     *
     * @return the number of pages in the PDF file.
     */
    public int getNumberOfPages() {
        return numberOfPages;
    }

    /**
     * Loads a page.
     *
     * @param pageNumber the number of the page that has to be loaded.
     * @return the PDFPage that has been loaded.
     */
    public synchronized PDFPage loadPage(int pageNumber) {
        pageNumber--;
        if (busy[pageNumber]) {
            return null;
        }
        busy[pageNumber] = true;
        PDFPage page = file.getPage(pageNumber + 1, true);
        if (!done[pageNumber]) {
            System.out.println("Loading page " + (pageNumber + 1));
        }
        done[pageNumber] = true;
        busy[pageNumber] = false;
        return page;
    }

    /**
     * @see com.lowagie.rups.model.BackgroundTask#doTask()
     */
    @Override
    public void doTask() {
        for (int i = 0; i < numberOfPages; i++) {
            loadPage(i + 1);
        }
    }
}