/*
* {{{ header & license
* Copyright (c) 2016 Stanimir Stamenkov
*
* This program 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 program 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 program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
* }}}
*/
package org.xhtmlrenderer.pdf;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.DocumentTraversal;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.NodeIterator;
import org.xhtmlrenderer.pdf.ITextOutputDevice.Bookmark;
import org.xhtmlrenderer.render.Box;
class HTMLOutline {
private static final Pattern HEADING =
Pattern.compile("h([1-6])", Pattern.CASE_INSENSITIVE);
/** <a href="https://www.w3.org/TR/html51/sections.html#sectioning-roots">sectioning roots</a> */
private static final Pattern ROOT =
Pattern.compile("blockquote|details|fieldset|figure|td",
Pattern.CASE_INSENSITIVE);
private static final Pattern WS = Pattern.compile("\\s+");
private static final int MAX_NAME_LENGTH = 200;
private final HTMLOutline parent;
private final int level;
private final Bookmark bookmark;
private HTMLOutline() {
this(0, "root", null);
}
private HTMLOutline(int level, String name, HTMLOutline parent) {
this.level = level;
this.bookmark = new Bookmark(name, "");
this.parent = parent;
if (parent != null) {
parent.bookmark.addChild(bookmark);
}
}
/**
* Creates a bookmark list of the document outline generated for the given
* element context (usually the root document element).
* <p>
* The current algorithm is more simple than the one suggested in the HTML5
* specification such as it is not affected by
* <a href="https://www.w3.org/TR/html51/dom.html#sectioning-content">sectioning
* content</a> but just the heading level. For
* <a href="https://www.w3.org/TR/html51/sections.html#example-d42b7aaf">example</a>:</p>
* <pre>
* <body>
* <h1>Foo</h1>
* <h3>Bar</h3>
* <blockquote>
* <h5>Bla</h5>
* </blockquote>
* <p>Baz</p>
* <h2>Quux</h2>
* <section>
* <h3>Thud</h3>
* </section>
* <h4>Grunt</h4>
* </body></pre>
* <p>
* Should generate outline as:</p>
* <ol>
* <li>Foo
* <ol>
* <li>Bar</li>
* <li>Quux</li>
* <li>Thud</li>
* <li>Grunt</li>
* </ol></li>
* </ol>
* <p>
* But it generates outline as:</p>
* <ol>
* <li>Foo
* <ol>
* <li>Bar</li>
* <li>Quux
* <ol>
* <li>Thud
* <ol>
* <li>Grunt</li>
* </ol></li>
* </ol></li>
* </ol></li>
* </ol>
*
* <h4>Example document customizations</h4>
*
* <h5>Include non-heading element as bookmark (level 4)</h5>
* <pre>
* <strong data-pdf-bookmark="4">Foo bar</strong></pre>
*
* <h5>Specify bookmark name</h5>
* <pre>
* <tr data-pdf-bookmark="5" data-pdf-bookmark-name="Bar baz">...</tr></pre>
*
* <h5>Exclude individual heading from bookmarks</h5>
* <pre>
* <h3 data-pdf-bookmark="none">Baz qux</h3></pre>
*
* <h5>Prevent automatic bookmarks for the whole of the document</h5>
* <pre>
* <html data-pdf-bookmark="exclude">...</html></pre>
*
* @param context the top element a sectioning outline would be generated for;
* @param box box hierarchy the outline bookmarks would get mapped into.
* @return Bookmarks of the outline generated for the given element context.
* @see <a href="https://www.w3.org/TR/html51/sections.html#creating-an-outline">Creating an outline</a>
*/
public static List<Bookmark> generate(Element context, Box box) {
NodeIterator iterator = NestedSectioningFilter.iterator(context);
HTMLOutline root = new HTMLOutline();
HTMLOutline current = root;
Map<Element,Bookmark> map = new IdentityHashMap();
for (Element element = (Element) iterator.nextNode();
element != null; element = (Element) iterator.nextNode()) {
int level;
try {
level = Integer.parseInt(getOutlineLevel(element));
if (level < 1) {
continue; // Illegal value
}
} catch (NumberFormatException e) {
continue; // Invalid value
}
String name = getBookmarkName(element);
while (current.level >= level) {
current = current.parent;
}
current = new HTMLOutline(level, name, current);
map.put(element, current.bookmark);
}
initBoxRefs(map, box);
return root.bookmark.getChildren();
} // generate(Element, Box) : List<Bookmark>
private static void initBoxRefs(Map<Element,Bookmark> map, Box box) {
Bookmark bookmark = map.get(box.getElement());
if (bookmark != null) {
bookmark.setBox(box);
}
for (int i = 0, len = box.getChildCount(); i < len; i++) {
initBoxRefs(map, box.getChild(i));
}
}
private static String getBookmarkName(Element element) {
String name = element.getAttribute("data-pdf-bookmark-name").trim();
if (name.isEmpty()) {
name = element.getTextContent();
}
name = WS.matcher(name.trim()).replaceAll(" ");
if (name.length() > MAX_NAME_LENGTH) {
name = name.substring(0, MAX_NAME_LENGTH);
}
return name;
}
static String getOutlineLevel(Element element) {
String bookmark = element.getAttribute("data-pdf-bookmark").trim();
if (bookmark.isEmpty()) {
Matcher heading = HEADING.matcher(element.getTagName());
if (heading.matches()) {
bookmark = heading.group(1);
} else if (ROOT.matcher(element.getTagName()).matches()) {
bookmark = "exclude";
} else {
bookmark = "none";
}
}
return bookmark;
}
private static class NestedSectioningFilter implements NodeFilter {
static final NestedSectioningFilter INSTANCE = new NestedSectioningFilter();
static NodeIterator iterator(Element root) {
return ((DocumentTraversal) root.getOwnerDocument())
.createNodeIterator(root, SHOW_ELEMENT, INSTANCE, true);
}
@Override
public short acceptNode(Node n) {
String outlineLevel = getOutlineLevel((Element) n);
if (outlineLevel.equalsIgnoreCase("none")) {
return FILTER_SKIP;
}
return outlineLevel.equalsIgnoreCase("exclude")
? FILTER_REJECT
: FILTER_ACCEPT;
}
} // class NestedSectioningFilter
} // class HTMLOutline