    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
    015    package org.apache.tapestry5.corelib.components;
    016
    017    import org.apache.tapestry5.*;
    018    import org.apache.tapestry5.annotations.Parameter;
    019    import org.apache.tapestry5.annotations.SupportsInformalParameters;
    020    import org.apache.tapestry5.dom.Element;
    021    import org.apache.tapestry5.ioc.annotations.Inject;
    022    import 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
    083    public 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    }