001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.html;
018
019import org.apache.juneau.svl.*;
020
021/**
022 * Defines an interface for resolvers of <js>"$W{...}"</js> string variables.
023 *
024 * <p>
025 * Widgets must provide one of the following public constructors:
026 * <ul>
027 *    <li><code><jk>public</jk> Widget();</code>
028 * </ul>
029 *
030 * <p>
031 * Widgets can be defined as inner classes of REST resource classes.
032 *
033 * <h5 class='section'>See Also:</h5><ul>
034 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/HtmlWidgets">Widgets</a>
035 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/HtmlBasics">HTML Basics</a>
036 * </ul>
037 */
038public interface HtmlWidget {
039
040   /**
041    * The name for this widget.
042    *
043    * @return A unique identifying name for this widget.
044    */
045   String getName();
046
047   /**
048    * Resolves the HTML content for this widget.
049    *
050    * <p>
051    * A returned value of <jk>null</jk> will cause nothing to be added to the page.
052    *
053    * @param session The current serializer session.
054    * @return The HTML content of this widget.
055    */
056   String getHtml(VarResolverSession session);
057
058   /**
059    * Resolves any Javascript that should be added to the <xt>&lt;head&gt;/&lt;script&gt;</xt> element.
060    *
061    * <p>
062    * A returned value of <jk>null</jk> will cause nothing to be added to the page.
063    *
064    * @param session The current serializer session.
065    * @return The Javascript needed by this widget.
066    */
067   String getScript(VarResolverSession session);
068
069   /**
070    * Resolves any CSS styles that should be added to the <xt>&lt;head&gt;/&lt;style&gt;</xt> element.
071    *
072    * <p>
073    * A returned value of <jk>null</jk> will cause nothing to be added to the page.
074    *
075    * @param session The current serializer session.
076    * @return The CSS styles needed by this widget.
077    */
078   String getStyle(VarResolverSession session);
079}