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

/*
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed 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.area;

// Java
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;
import java.util.Iterator;

// XML
import org.xml.sax.SAXException;

// FOP
import org.apache.fop.apps.FOPException;
import org.apache.fop.apps.FOUserAgent;
import org.apache.fop.fonts.FontInfo;
import org.apache.fop.render.Renderer;
import org.apache.fop.render.RendererFactory;

/**
 * This uses the AreaTreeModel 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 AreaTreeModel {
    /**
     * 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 pendingODI = new java.util.ArrayList();
    private List endDocODI = new java.util.ArrayList();

    /**
     * Create a new render pages model with the given renderer.
     * @param userAgent FOUserAgent object for process
     * @param renderType Desired fo.Constants output type (RENDER_PDF, 
     *   RENDER_PS, etc.)
     * @param fontInfo FontInfo object
     * @param stream OutputStream
     * @throws FOPException if the renderer cannot be properly initialized
     */
    public RenderPagesModel (FOUserAgent userAgent, int renderType, 
        FontInfo fontInfo, OutputStream stream) throws FOPException {

        super();
        renderer = RendererFactory.createRenderer(userAgent, renderType);

        try {
            renderer.setupFontInfo(fontInfo);
            // check that the "any,normal,400" font exists
            if (!fontInfo.isSetupValid()) {
                throw new FOPException(
                    "No default font defined by OutputConverter");
            }
            renderer.startRenderer(stream);
        } catch (IOException e) {
            throw new FOPException(e);
        }
    }

    /**
     * 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(LineArea 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, false);

        if (cont) {
            processOffDocumentItems(pendingODI);
            pendingODI.clear();
        }
    }

    /**
     * Check prepared pages
     *
     * @param newpage the new page being added
     * @param renderUnresolved render pages with unresolved idref's
     *          (done at end-of-document processing)
     * @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, boolean
        renderUnresolved) {
        for (Iterator iter = prepared.iterator(); iter.hasNext();) {
            PageViewport p = (PageViewport)iter.next();
            if (p.isResolved() || renderUnresolved) {
                try {
                    renderer.renderPage(p);
                    if (!p.isResolved()) {
                        String[] idrefs = p.getIDRefs();
                        for (int count = 0; count < idrefs.length; count++) {
                            log.warn("Page " + p.getPageNumberString() + 
                                ": Unresolved id reference \"" + idrefs[count] 
                                + "\" found.");
                        }
                    }
                } 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);
    }

    /**
     * @see org.apache.fop.area.AreaTreeModel#handleOffDocumentItem(OffDocumentItem)
     */
    public void handleOffDocumentItem(OffDocumentItem oDI) {
        switch(oDI.getWhenToProcess()) {
            case OffDocumentItem.IMMEDIATELY:
                renderer.processOffDocumentItem(oDI);
                break;
            case OffDocumentItem.AFTER_PAGE:
                pendingODI.add(oDI);
                break;
            case OffDocumentItem.END_OF_DOC:
                endDocODI.add(oDI);
                break;
        }
    }

    private void processOffDocumentItems(List list) {
        for (int count = 0; count < list.size(); count++) {
            OffDocumentItem oDI = (OffDocumentItem)list.get(count);
            renderer.processOffDocumentItem(oDI);
        }
    }

    /**
     * End the document. Render any end document OffDocumentItems
     * @see org.apache.fop.area.AreaTreeModel#endDocument()
     */
    public void endDocument() throws SAXException {
        // render any pages that had unresolved ids
        checkPreparedPages(null, true);

        processOffDocumentItems(pendingODI);
        pendingODI.clear();
        processOffDocumentItems(endDocODI);

        try {
            renderer.stopRenderer();
        } catch (IOException ex) {
            throw new SAXException(ex);
        }
    }
}