fop/src/java/org/apache/fop/area/RenderPagesModel.java

/*
 * $Id: RenderPagesModel.java,v 1.3 2003/03/05 15:19:31 jeremias Exp $
 * ============================================================================
 *                    The Apache Software License, Version 1.1
 * ============================================================================
 * 
 * Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * 3. The end-user documentation included with the redistribution, if any, must
 *    include the following acknowledgment: "This product includes software
 *    developed by the Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself, if
 *    and wherever such third-party acknowledgments normally appear.
 * 
 * 4. The names "FOP" and "Apache Software Foundation" must not be used to
 *    endorse or promote products derived from this software without prior
 *    written permission. For written permission, please contact
 *    apache@apache.org.
 * 
 * 5. Products derived from this software may not be called "Apache", nor may
 *    "Apache" appear in their name, without prior written permission of the
 *    Apache Software Foundation.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * APACHE SOFTWARE FOUNDATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLU-
 * DING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ============================================================================
 * 
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Apache Software Foundation and was originally created by
 * James Tauber <jtauber@jtauber.com>. For more information on the Apache
 * Software Foundation, please see <http://www.apache.org/>.
 */ 
package org.apache.fop.area;

// FOP
import org.apache.fop.render.Renderer;

// Java
import java.util.List;
import java.util.Iterator;

/**
 * This uses the store pages model to store the pages
 * each page is either rendered if ready or prepared
 * for later rendering.
 * Once a page is rendered it is cleared to release the
 * contents but the PageViewport is retained. So even
 * though the pages are stored the contents are discarded.
 */
public class RenderPagesModel extends StorePagesModel {
    /**
     * The renderer that will render the pages.
     */
    protected Renderer renderer;
    /**
     * Pages that have been prepared but not rendered yet.
     */
    protected List prepared = new java.util.ArrayList();
    private List pendingExt = new java.util.ArrayList();
    private List endDocExt = new java.util.ArrayList();

    /**
     * Create a new render pages model with the given renderer.
     * @param rend the renderer to render pages to
     */
    public RenderPagesModel(Renderer rend) {
        renderer = rend;
    }

    /**
     * Start a new page sequence.
     * This tells the renderer that a new page sequence has
     * started with the given title.
     * @param title the title of the new page sequence
     */
    public void startPageSequence(Title title) {
        super.startPageSequence(title);
        renderer.startPageSequence(title);
    }

    /**
     * Add a page to the render page model.
     * If the page is finished it can be rendered immediately.
     * If the page needs resolving then if the renderer supports
     * out of order rendering it can prepare the page. Otherwise
     * the page is added to a queue.
     * @param page the page to add to the model
     */
    public void addPage(PageViewport page) {
        super.addPage(page);

        // for links the renderer needs to prepare the page
        // it is more appropriate to do this after queued pages but
        // it will mean that the renderer has not prepared a page that
        // could be referenced
        boolean done = renderer.supportsOutOfOrder() && page.isResolved();
        if (done) {
            try {
                renderer.renderPage(page);
            } catch (Exception e) {
                // use error handler to handle this FOP or IO Exception
                e.printStackTrace();
            }
            page.clear();
        } else {
            preparePage(page);
        }


        // check prepared pages
        boolean cont = checkPreparedPages(page);

        if (cont) {
            renderExtensions(pendingExt);
            pendingExt.clear();
        }
    }

    /**
     * Check prepared pages
     *
     * @param newpage the new page being added
     * @return true if the current page should be rendered
     *         false if the renderer doesn't support out of order
     *         rendering and there are pending pages
     */
    protected boolean checkPreparedPages(PageViewport newpage) {
        for (Iterator iter = prepared.iterator(); iter.hasNext();) {
            PageViewport p = (PageViewport)iter.next();
            if (p.isResolved()) {
                try {
                    renderer.renderPage(p);
                } catch (Exception e) {
                    // use error handler to handle this FOP or IO Exception
                    e.printStackTrace();
                }
                p.clear();
                iter.remove();
            } else {
                // if keeping order then stop at first page not resolved
                if (!renderer.supportsOutOfOrder()) {
                    break;
                }
            }
        }
        return renderer.supportsOutOfOrder() || prepared.isEmpty();
    }

    /**
     * Prepare a page.
     * An unresolved page can be prepared if the renderer supports
     * it and the page will be rendered later.
     * @param page the page to prepare
     */
    protected void preparePage(PageViewport page) {
        if (renderer.supportsOutOfOrder()) {
            renderer.preparePage(page);
        }
        prepared.add(page);
    }

    /**
     * Add an extension to this model.
     * If handle immediately then send directly to the renderer.
     * The after page ones are handled after the next page is added.
     * End of document extensions are added to a list to be
     * handled at the end.
     * @param ext the extension
     * @param when when to render the extension
     */
    public void addExtension(TreeExt ext, int when) {
        switch(when) {
            case TreeExt.IMMEDIATELY:
                renderer.renderExtension(ext);
                break;
            case TreeExt.AFTER_PAGE:
                pendingExt.add(ext);
                break;
            case TreeExt.END_OF_DOC:
                endDocExt.add(ext);
                break;
        }
    }

    private void renderExtensions(List list) {
        for (int count = 0; count < list.size(); count++) {
            TreeExt ext = (TreeExt)list.get(count);
            renderer.renderExtension(ext);
        }
    }

    /**
     * End the document. Render any end document extensions.
     */
    public void endDocument() {
        // render any pages that had unresolved ids
        checkPreparedPages(null);

        renderExtensions(pendingExt);
        pendingExt.clear();

        renderExtensions(endDocExt);
    }
}