001// Copyright 2007, 2008, 2009, 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.BindingConstants;
018import org.apache.tapestry5.Block;
019import org.apache.tapestry5.CSSClassConstants;
020import org.apache.tapestry5.ClientBodyElement;
021import org.apache.tapestry5.ComponentAction;
022import org.apache.tapestry5.ComponentResources;
023import org.apache.tapestry5.ComponentParameterConstants;
024import org.apache.tapestry5.MarkupWriter;
025import org.apache.tapestry5.QueryParameterConstants;
026import org.apache.tapestry5.annotations.BeginRender;
027import org.apache.tapestry5.annotations.Environmental;
028import org.apache.tapestry5.annotations.Parameter;
029import org.apache.tapestry5.annotations.SupportsInformalParameters;
030import org.apache.tapestry5.corelib.internal.ComponentActionSink;
031import org.apache.tapestry5.corelib.internal.FormSupportAdapter;
032import org.apache.tapestry5.corelib.internal.HiddenFieldPositioner;
033import org.apache.tapestry5.dom.Element;
034import org.apache.tapestry5.ioc.annotations.Inject;
035import org.apache.tapestry5.services.ClientBehaviorSupport;
036import org.apache.tapestry5.services.ClientDataEncoder;
037import org.apache.tapestry5.services.Environment;
038import org.apache.tapestry5.services.FormSupport;
039import org.apache.tapestry5.services.Heartbeat;
040import org.apache.tapestry5.services.HiddenFieldLocationRules;
041import org.apache.tapestry5.services.javascript.JavaScriptSupport;
042import org.slf4j.Logger;
043
044/**
045 * A Zone is portion of the output page designed for easy dynamic updating via Ajax or other client-side effects. A
046 * Zone renders out as a <div> element (or whatever is specified in the template) and may have content initially,
047 * or may only get its content as a result of client side activity.
048 * <p/>
049 * Often, Zones are initially invisible, in which case the visible parameter may be set to false (it defaults to true).
050 * <p/>
051 * When a user clicks an {@link org.apache.tapestry5.corelib.components.ActionLink} whose zone parameter is set, the
052 * corresponding client-side Tapestry.ZoneManager object is located. It will update the content of the Zone's
053 * &lt;div&gt; and then invoke either a show method (if the div is not visible) or an update method (if the div is
054 * visible). The show and update parameters are the <em>names</em> of functions attached to the Tapestry.ElementEffect
055 * object. Likewise, a {@link org.apache.tapestry5.corelib.components.Form} component may also trigger an update of a
056 * client-side Zone.
057 * <p/>
058 * The server side event handler can return a {@link org.apache.tapestry5.Block} or a component to render as the new
059 * content on the client side. Often, re-rendering the Zone's {@linkplain #getBody() body} is useful. Multiple
060 * client-side zones may be updated by returning a {@link org.apache.tapestry5.ajax.MultiZoneUpdate}.
061 * <p/>
062 * Renders informal parameters, adding CSS class "t-zone" and possibly, "t-invisible".
063 * <p/>
064 * You will often want to specify the id parameter of the Zone, in addition to it's Tapestry component id; this "locks
065 * down" the client-side id, so the same value is used even in later partial renders of the page (essential if the Zone
066 * is nested inside another Zone). When you specify the client-side id, it is used exactly as provided (meaning that you
067 * are responsible for ensuring that there will not be an id conflict even in the face of multiple partial renders of
068 * the page). Failure to provide an explicit id results in a new, and non-predictable, id being generated for each
069 * partial render, which will often result in client-side failures to locate the element to update when the Zone is
070 * triggered.
071 * <p>
072 * In some cases, you may want to know (on the server side) the client id of the zone that was updated; this is passed
073 * as part of the Ajax request, as the {@link QueryParameterConstants#ZONE_ID} parameter. An example use of this would
074 * be to provide new content into a Zone that updates the same Zone, when the Zone's client-side id is dynamically
075 * allocated (rather than statically defined). In most cases, however, the programmer is responsible for assigning a
076 * specific client-side id, via the id parameter.
077 * <p/>
078 * A Zone starts and stops a {@link Heartbeat} when it renders (both normally, and when re-rendering).
079 * <p/>
080 * After the client-side content is updated, a client-side event is fired on the zone's element. The constant
081 * Tapestry.ZONE_UPDATED_EVENT can be used to listen to the event.
082 * 
083 * @tapestrydoc
084 * @see AjaxFormLoop
085 * @see FormFragment
086 */
087@SupportsInformalParameters
088public class Zone implements ClientBodyElement
089{
090    /**
091     * Name of a function on the client-side Tapestry.ElementEffect object that is invoked to make the Zone's
092     * &lt;div&gt; visible before being updated. If not specified, then the basic "show" method is used.
093     */
094    @Parameter(defaultPrefix = BindingConstants.LITERAL,
095        value = BindingConstants.SYMBOL + ":" + ComponentParameterConstants.ZONE_SHOW_METHOD)
096    private String show;
097
098    /**
099     * Name of a function on the client-side Tapestry.ElementEffect object that is invoked after the Zone's content has
100     * been updated. If not specified, then the basic "highlight" method is used, which performs a classic "yellow fade"
101     * to indicate to the user that and update has taken place.
102     */
103    @Parameter(defaultPrefix = BindingConstants.LITERAL,
104        value = BindingConstants.SYMBOL + ":" + ComponentParameterConstants.ZONE_UPDATE_METHOD)
105    private String update;
106
107    /**
108     * The element name to render for the zone; this defaults to the element actually used in the template, or "div" if
109     * no specific element was specified.
110     */
111    @Parameter(required = true, allowNull = false, defaultPrefix = BindingConstants.LITERAL)
112    private String elementName;
113
114    /**
115     * If bound, then the id attribute of the rendered element will be this exact value. If not bound, then a unique id
116     * is generated for the element.
117     */
118    @Parameter(name = "id", defaultPrefix = BindingConstants.LITERAL)
119    private String idParameter;
120
121    @Environmental
122    private JavaScriptSupport javascriptSupport;
123
124    @Environmental
125    private ClientBehaviorSupport clientBehaviorSupport;
126
127    @Inject
128    private Environment environment;
129
130    /**
131     * If true (the default) then the zone will render normally. If false, then the "t-invisible" CSS class is added,
132     * which will make the zone initially invisible.
133     */
134    @Parameter
135    private boolean visible = true;
136
137    @Inject
138    private ComponentResources resources;
139
140    @Inject
141    private Heartbeat heartbeat;
142
143    @Inject
144    private Logger logger;
145
146    @Inject
147    private ClientDataEncoder clientDataEncoder;
148
149    @Inject
150    private HiddenFieldLocationRules rules;
151
152    private String clientId;
153
154    private boolean insideForm;
155
156    private HiddenFieldPositioner hiddenFieldPositioner;
157
158    private ComponentActionSink actionSink;
159
160    String defaultElementName()
161    {
162        return resources.getElementName("div");
163    }
164
165    void beginRender(MarkupWriter writer)
166    {
167        clientId = resources.isBound("id") ? idParameter : javascriptSupport.allocateClientId(resources);
168
169        Element e = writer.element(elementName, "id", clientId);
170
171        resources.renderInformalParameters(writer);
172
173        e.addClassName("t-zone");
174
175        if (!visible)
176            e.addClassName(CSSClassConstants.INVISIBLE);
177
178        clientBehaviorSupport.addZone(clientId, show, update);
179
180        FormSupport existingFormSupport = environment.peek(FormSupport.class);
181
182        insideForm = existingFormSupport != null;
183
184        if (insideForm)
185        {
186            hiddenFieldPositioner = new HiddenFieldPositioner(writer, rules);
187
188            actionSink = new ComponentActionSink(logger, clientDataEncoder);
189
190            environment.push(FormSupport.class, new FormSupportAdapter(existingFormSupport)
191            {
192                @Override
193                public <T> void store(T component, ComponentAction<T> action)
194                {
195                    actionSink.store(component, action);
196                }
197
198                @Override
199                public <T> void storeAndExecute(T component, ComponentAction<T> action)
200                {
201                    store(component, action);
202
203                    action.execute(component);
204                }
205
206            });
207        }
208
209        heartbeat.begin();
210    }
211
212    void afterRender(MarkupWriter writer)
213    {
214        heartbeat.end();
215
216        if (insideForm)
217        {
218            environment.pop(FormSupport.class);
219
220            if (actionSink.isEmpty())
221            {
222                hiddenFieldPositioner.discard();
223            }
224            else
225            {
226                hiddenFieldPositioner.getElement().attributes("type", "hidden",
227
228                "name", Form.FORM_DATA,
229
230                "value", actionSink.getClientData());
231            }
232        }
233
234        writer.end(); // div
235    }
236
237    /**
238     * The client id of the Zone; this is set when the Zone renders and will either be the value bound to the id
239     * parameter, or an allocated unique id. When the id parameter is bound, this value is always accurate.
240     * When the id parameter is not bound, the clientId is set during the {@linkplain BeginRender begin render phase}
241     * and will be null or inaccurate before then.
242     * 
243     * @return client-side element id
244     */
245    public String getClientId()
246    {
247        if (resources.isBound("id"))
248            return idParameter;
249
250        return clientId;
251    }
252
253    /**
254     * Returns the zone's body (the content enclosed by its start and end tags). This is often used as part of an Ajax
255     * partial page render to update the client with a fresh render of the content inside the zone.
256     * 
257     * @return the zone's body as a Block
258     */
259    public Block getBody()
260    {
261        return resources.getBody();
262    }
263}