filter out invisible elements

src/com/dom_distiller/client/DomToSaxParser.java

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package com.dom_distiller.client;
-
-import com.google.gwt.core.client.JsArray;
-import com.google.gwt.dom.client.Element;
-import com.google.gwt.dom.client.Node;
-import com.google.gwt.dom.client.NodeList;
-import com.google.gwt.dom.client.Text;
-
-import org.xml.sax.Attributes;
-import org.xml.sax.AttributesImpl;
-import org.xml.sax.ContentHandler;
-import org.xml.sax.SAXException;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.logging.Logger;
-
-/**
- * Used to generate sax events from the DOM tree.
- */
-public class DomToSaxParser {
-    static Logger logger = Logger.getLogger("DomToSaxParser");
-
-    private static class DomToSaxVisitor implements DomWalker.Visitor {
-        private static final String sHtmlNamespace = "http://www.w3.org/1999/xhtml";
-        private final ContentHandler handler;
-        private List<Node> textNodes;
-
-        DomToSaxVisitor(ContentHandler h) {
-            handler = h;
-            textNodes = new ArrayList<Node>();
-        }
-
-        @Override
-        public boolean visit(Node n) {
-            try {
-                switch (n.getNodeType()) {
-                    case Node.TEXT_NODE:
-                        textNodes.add(n);
-                        String text = Text.as(n).getData();
-                        handler.characters(text.toCharArray(), 0, text.length());
-                        return false;
-                    case Node.ELEMENT_NODE:
-                        Element e = Element.as(n);
-                        Attributes attrs = getSaxAttributes(e);
-                        handler.startElement(sHtmlNamespace, e.getTagName(), e.getTagName(), attrs);
-                        return true;
-                    case Node.DOCUMENT_NODE:  // Don't recurse into sub-documents.
-                    default:  // This case is for comment nodes.
-                        return false;
-                }
-            } catch (SAXException e) {
-                return false;
-            }
-        }
-
-        @Override
-        public void exit(Node n) {
-            Element e = Element.as(n);
-            try {
-                handler.endElement(sHtmlNamespace, e.getTagName(), e.getTagName());
-            } catch (SAXException ex) {
-                // Intentionally ignored.
-            }
-        }
-    }
-
-    /**
-     * This will generate sax events for the DOM tree rooted at e to the provided ContentHandler.
-     *
-     * @Return A list of the text nodes (in order).
-     */
-    static List<Node> parse(Element e, ContentHandler handler) {
-        DomToSaxVisitor visitor = new DomToSaxVisitor(handler);
-        new DomWalker(visitor).walk(e);
-        return visitor.textNodes;
-    }
-
-    /**
-     * @Return The element's attribute list converted to org.xml.sax.Attributes.
-     */
-    public static Attributes getSaxAttributes(Element e) {
-        AttributesImpl attrs = new AttributesImpl();
-
-        JsArray<Node> jsAttrs = DomUtil.getAttributes(e);
-        for (int i = 0; i < jsAttrs.length(); ++i) {
-            final Node jsAttr = jsAttrs.get(i);
-            attrs.addAttribute("", jsAttr.getNodeName(), jsAttr.getNodeName(), "CDATA", jsAttr.getNodeValue());
-        }
-
-        return attrs;
-    }
-}