    001// Copyright 2008, 2010, 2011 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007// http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.corelib.components;
    016
    017import org.apache.tapestry5.*;
    018import org.apache.tapestry5.annotations.Parameter;
    019import org.apache.tapestry5.annotations.SupportsInformalParameters;
    020import org.apache.tapestry5.dom.Element;
    021import org.apache.tapestry5.ioc.annotations.Inject;
    022import org.apache.tapestry5.services.javascript.JavaScriptSupport;
    023
    024/**
    025 * Turns any arbitrary (X)HTML element into a component. The element's start and end
    026 * tags are rendered, including any informal parameters and possibly an id
    027 * attribute.  The id is provided by {@link JavaScriptSupport#allocateClientId(String)}
    028 * (so it will be unique on the client side) and is available after the component
    029 * renders using {@link #getClientId()}. The Any component has no template of its
    030 * own but does render its body, if any.
    031 * <p>
    032 * Some common uses are:
    033 * <ul>
    034 *
    035 * <li>Applying a mixin to an ordinary HTML element. For example,
    036 * the following turns an <i>img</i> element into a component that, via the
    037 * {@link org.apache.tapestry5.corelib.mixins.RenderNotification RenderNotification} mixin, triggers event
    038 * notifications when it enters the BeginRender and EndRender phases:
    039 *
    040 * <pre>&lt;img t:type="any" t:mixins="renderNotification"&gt;</pre>
    041 *
    042 * And the following renders a <i>td</i> element with the
    043 * {@link org.apache.tapestry5.corelib.mixins.NotEmpty NotEmpty} mixin to ensure
    044 * that a non-breaking space (&amp;nbsp;) is rendered if the td element would
    045 * otherwise be empty:
    046 *
    047 * <pre>&lt;td t:type="any" t:mixins="NotEmpty"&gt;</pre>
    048 * </li>
    049 *
    050 * <li>Providing a dynamically-generated client ID for an HTML element
    051 * in a component rendered in a loop or zone (or more than once in a page), for
    052 * use from JavaScript. (The component class will typically use
    053 * {@link org.apache.tapestry5.annotations.InjectComponent InjectComponent}
    054 * to get the component, then call {@link #getClientId()} to retrieve the ID.)
    055 *
    056 * <pre>&lt;table t:type="any" id="clientId"&gt;</pre>
    057 *
    058 * As an alternative to calling getClientId, you can use the
    059 * {@link org.apache.tapestry5.corelib.mixins.RenderClientId RenderClientId}
    060 * mixin to force the id attribute to appear in the HTML:
    061 *
    062 * <pre>&lt;table t:type="any" t:mixins="RenderClientId"&gt;</pre>
    063 * </li>
    064 *
    065 * <li>Dynamically outputting a different HTML element depending on
    066 * the string value of a property. For example, the following renders an element
    067 * identified by the "element" property in the corresponding component class:
    068 *
    069 * <pre>&lt;t:any element="prop:element" ... &gt;</pre>
    070 * </li>
    071 *
    072 * <li>As the base component for a new custom component, especially convenient
    073 * when the new component should support informal parameters or needs a dynamically
    074 * generated client ID:
    075 *
    076 * <pre>public class MyComponent extends Any { ... }
    077 * </li>
    078 * </ul>
    079 *
    080 * @tapestrydoc
    081 */
    082@SupportsInformalParameters
    083public class Any implements ClientElement
    084{
    085    /**
    086     * The name of the element to be rendered, typically one of the standard (X)HTML
    087     * elements, "div", "span", "a", etc., although practically any string will be
    088     * accepted. The default comes from the template, or is "div" if the template
    089     * does not specify an element.
    090     */
    091    @Parameter(defaultPrefix = BindingConstants.LITERAL)
    092    private String element;
    093
    094    /**
    095     * The desired client id, which defaults to the component's id.
    096     */
    097    @Parameter(value = "prop:componentResources.id", defaultPrefix = BindingConstants.LITERAL)
    098    private String clientId;
    099
    100    private Element anyElement;
    101
    102    private String uniqueId;
    103
    104    @Inject
    105    private ComponentResources resources;
    106
    107    @Inject
    108    private JavaScriptSupport javascriptSupport;
    109
    110    String defaultElement()
    111    {
    112        return resources.getElementName("div");
    113    }
    114
    115    void beginRender(MarkupWriter writer)
    116    {
    117        anyElement = writer.element(element);
    118
    119        uniqueId = null;
    120
    121        resources.renderInformalParameters(writer);
    122    }
    123
    124    /**
    125     * Returns the client id. This has side effects: this first time this is called (after the Any component renders
    126     * its start tag), a unique id is allocated (based on, and typically the same as, the clientId parameter, which
    127     * defaults to the component's id). The rendered element is updated, with its id attribute set to the unique client
    128     * id, which is then returned.
    129     *
    130     * @return unique client id for this component
    131     */
    132    public String getClientId()
    133    {
    134        if (anyElement == null)
    135            throw new IllegalStateException(String.format(
    136                    "Unable to provide client id for component %s as it has not yet rendered.", resources
    137                            .getCompleteId()));
    138
    139        if (uniqueId == null)
    140        {
    141            uniqueId = javascriptSupport.allocateClientId(clientId);
    142            anyElement.forceAttributes("id", uniqueId);
    143        }
    144
    145        return uniqueId;
    146    }
    147
    148    void afterRender(MarkupWriter writer)
    149    {
    150        writer.end(); // the element
    151    }
    152
    153    void inject(JavaScriptSupport javascriptSupport, ComponentResources resources, String element, String clientId)
    154    {
    155        this.javascriptSupport = javascriptSupport;
    156        this.resources = resources;
    157        this.element = element;
    158        this.clientId = clientId;
    159    }
    160}