com.google.livingstories.client.contentmanager.ObjectElementProofreader.java Source code

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Here is the source code for com.google.livingstories.client.contentmanager.ObjectElementProofreader.java

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/**
 * Copyright 2010 Google Inc.
 *
 * 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.
 */

package com.google.livingstories.client.contentmanager;

import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NodeList;
import com.google.gwt.user.client.ui.HTML;

/**
 * Class used for proofreading HTML that contains <object> and <embed> tags, turning them into
 * a canonical form that is cross-browser compatible.
 */
public class ObjectElementProofreader {
    /**
     * Class that contains information on which attributes of an <embed> tag should make
     * it into the corresponding <object> tag.
     * @author hiller@google.com (Matt Hiller)
     *
     */
    private enum TranslatedAttributeRecord {
        WIDTH("width", "width", true), HEIGHT("height", "height", true), SRC("src", "data", false), TYPE("type",
                "type", false);

        private String embedAttribute;
        private String objectAttribute;
        private boolean removePx;

        TranslatedAttributeRecord(String embedAttribute, String objectAttribute, boolean removePx) {
            this.embedAttribute = embedAttribute;
            this.objectAttribute = objectAttribute;
            this.removePx = removePx;
        }

        public static TranslatedAttributeRecord getFromEmbedAttribute(String embedAttribute) {
            for (TranslatedAttributeRecord record : TranslatedAttributeRecord.values()) {
                if (record.embedAttribute.equalsIgnoreCase(embedAttribute)) {
                    return record;
                }
            }
            return null;
        }

        public void setAttributeForObject(Element objectElement, String value) {
            if (removePx && value.endsWith("px")) {
                value = value.replaceFirst("px$", "");
            }
            objectElement.setAttribute(objectAttribute, value);
        }
    }

    private static String[] EMBED_ATTRIBUTES = {
            // Per http://kb2.adobe.com/cps/127/tn_12701.html:
            "width", "height", "src", "type", "id", "name", "swliveconnect", "play", "loop", "menu", "quality",
            "scale", "align", "salign", "wmode", "bgcolor", "base", "flashvars" };

    private Document document = Document.get();

    public String proofread(String incomingHtml) {
        HTML asHTML = new HTML(incomingHtml);
        Element element = asHTML.getElement();
        boolean changed = false;

        NodeList<Element> embeds = element.getElementsByTagName("embed");

        // since we will be removing embeds, iterate from len-1 to 0:
        for (int i = embeds.getLength() - 1; i >= 0; i--) {
            changed = true;
            Element embed = embeds.getItem(i);
            Element embedParent = embed.getParentElement();
            if (embedParent.getTagName().equalsIgnoreCase("object")) {
                // The wrapped object idiom: shouldn't be necessary at all.
                embedParent.removeChild(embed);
            } else {
                Element objectElement = document.createObjectElement();

                for (String attribute : EMBED_ATTRIBUTES) {
                    String value = embed.getAttribute(attribute);

                    if (!value.isEmpty()) {
                        TranslatedAttributeRecord record = TranslatedAttributeRecord
                                .getFromEmbedAttribute(attribute);

                        if (record == null) {
                            addParam(objectElement, attribute, value);
                        } else {
                            record.setAttributeForObject(objectElement, value);
                            if (record == TranslatedAttributeRecord.SRC) {
                                addParam(objectElement, "movie", value);
                            }
                        }
                    }
                }
                embedParent.replaceChild(objectElement /* new */, embed /* old */);
            }
        }

        // now iterate over objects, looking for places where the "data" value is not replicated as
        // a "movie" param.
        NodeList<Element> objectElements = element.getElementsByTagName("object");

        // again, iterate from len-1 to 0:
        for (int i = objectElements.getLength() - 1; i >= 0; i--) {
            Element objectElement = objectElements.getItem(i);
            Element objectParent = objectElement.getParentElement();

            if (objectParent.getTagName().equalsIgnoreCase("object")) {
                // nested object idiom. Unnecessary.
                changed = true;
                objectParent.removeChild(objectElement);
            } else {
                boolean foundMovieParam = false;

                for (Element child = objectElement.getFirstChildElement(); !foundMovieParam
                        && child != null; child = child.getNextSiblingElement()) {
                    foundMovieParam = child.getNodeName().equalsIgnoreCase("param")
                            && child.getAttribute("name").equalsIgnoreCase("movie");
                }

                if (!foundMovieParam) {
                    // duplicate it from the data attribute of the object itself.
                    changed = true;
                    addParam(objectElement, "movie", objectElement.getAttribute("data"));
                }
            }
        }

        return (changed
                // so that we don't worry about embedded comment indicators in the original html:
                ? (element.getInnerHTML() + "\n<!--\n" + incomingHtml.replaceAll("-+", "-") + "\n-->\n")
                : null);
    }

    private void addParam(Element objectElement, String name, String value) {
        Element param = document.createParamElement();
        param.setAttribute("name", name);
        param.setAttribute("value", value);
        objectElement.appendChild(param);
    }
}