Body


1   // Copyright 2004, 2005 The Apache Software Foundation
2   //
3   // Licensed under the Apache License, Version 2.0 (the "License");
4   // you may not use this file except in compliance with the License.
5   // You may obtain a copy of the License at
6   //
7   //     http://www.apache.org/licenses/LICENSE-2.0
8   //
9   // Unless required by applicable law or agreed to in writing, software
10  // distributed under the License is distributed on an "AS IS" BASIS,
11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  // See the License for the specific language governing permissions and
13  // limitations under the License.
14  
15  package org.apache.tapestry.html;
16  
17  import org.apache.hivemind.Resource;
18  import org.apache.tapestry.AbstractComponent;
19  import org.apache.tapestry.IMarkupWriter;
20  import org.apache.tapestry.IRequestCycle;
21  import org.apache.tapestry.PageRenderSupport;
22  import org.apache.tapestry.TapestryUtils;
23  import org.apache.tapestry.asset.AssetFactory;
24  import org.apache.tapestry.util.PageRenderSupportImpl;
25  import org.apache.tapestry.web.WebResponse;
26  
27  /**
28   * The body of a Tapestry page. This is used since it allows components on the page access to an
29   * initialization script (that is written the start, just inside the &lt;body&gt; tag). This is
30   * currently used by {@link Rollover}and {@link Script}components. [ <a
31   * HREF="../../../../../ComponentReference/Body.html">Component Reference </a>]
32   * 
33   * @author Howard Lewis Ship
34   */
35  
36  public abstract class Body extends AbstractComponent implements PageRenderSupport
37  {
38      private PageRenderSupportImpl _pageRenderSupport;
39  
40      /**
41       * Adds to the script an initialization for the named variable as an Image(), to the given URL.
42       * <p>
43       * Returns a reference, a string that can be used to represent the preloaded image in a
44       * JavaScript function.
45       * 
46       * @since 1.0.2
47       */
48  
49      public String   getPreloadedImageReference(String   URL)
50      {
51          return _pageRenderSupport.getPreloadedImageReference(URL);
52      }
53  
54      /**
55       * Adds other initialization, in the form of additional JavaScript code to execute from the
56       * &lt;body&gt;'s <code>onLoad</code> event handler. The caller is responsible for adding a
57       * semicolon (statement terminator). This method will add a newline after the script.
58       */
59  
60      public void addInitializationScript(String   script)
61      {
62          _pageRenderSupport.addInitializationScript(script);
63      }
64  
65      /**
66       * Adds additional scripting code to the page. This code will be added to a large block of
67       * scripting code at the top of the page (i.e., the before the &lt;body&gt; tag).
68       * <p>
69       * This is typically used to add some form of JavaScript event handler to a page. For example,
70       * the {@link Rollover}component makes use of this.
71       * <p>
72       * Another way this is invoked is by using the {@link Script}component.
73       * <p>
74       * The string will be added, as-is, within the &lt;script&gt; block generated by this
75       * <code>Body</code> component. The script should <em>not</em> contain HTML comments, those
76       * will be supplied by this Body component.
77       * <p>
78       * A frequent use is to add an initialization function using this method, then cause it to be
79       * executed using {@link #addInitializationScript(String)}.
80       */
81  
82      public void addBodyScript(String   script)
83      {
84          _pageRenderSupport.addBodyScript(script);
85      }
86  
87      /**
88       * Used to include a script from an outside URL (the scriptLocation is a URL, probably obtained
89       * from an asset. This adds an &lt;script SRC="..."&gt; tag before the main &lt;script&gt; tag.
90       * The Body component ensures that each URL is included only once.
91       * 
92       * @since 1.0.5
93       */
94  
95      public void addExternalScript(Resource scriptLocation)
96      {
97          _pageRenderSupport.addExternalScript(scriptLocation);
98      }
99  
100     /**
101      * Retrieves the <code>Body</code> that was stored into the request cycle. This allows
102      * components wrapped by the <code>Body</code> to locate it and access the services it
103      * provides.
104      * 
105      * @deprecated To be removed in 4.1. Use
106      *             {@link org.apache.tapestry.TapestryUtils#getPageRenderSupport(IRequestCycle)}
107      *             instead.
108      */
109 
110     public static Body get(IRequestCycle cycle)
111     {
112         return (Body) TapestryUtils.getPageRenderSupport(cycle, null);
113     }
114 
115     protected void prepareForRender(IRequestCycle cycle)
116     {
117         super.prepareForRender(cycle);
118 
119         _pageRenderSupport = new PageRenderSupportImpl(getAssetFactory(), getResponse()
120                 .getNamespace(), getLocation());
121     }
122 
123     protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
124     {
125         TapestryUtils.storePageRenderSupport(cycle, this);
126 
127         IMarkupWriter nested = writer.getNestedWriter();
128 
129         renderBody(nested, cycle);
130 
131         // Start the body tag.
132         writer.println();
133         writer.begin(getElement());
134         renderInformalParameters(writer, cycle);
135 
136         writer.println();
137 
138         // Write the page's scripting. This is included scripts
139         // and dynamic JavaScript.
140 
141         _pageRenderSupport.writeBodyScript(writer, cycle);
142 
143         // Close the nested writer, which dumps its buffered content
144         // into its parent.
145 
146         nested.close();
147 
148         // Any initialization should go at the very end of the document
149         // just before the close body tag. Older version of Tapestry
150         // would create a window.onload event handler, but this is better
151         // (it doesn't have to wait for external images to load).
152 
153         _pageRenderSupport.writeInitializationScript(writer);
154 
155         writer.end(); // <body>
156     }
157 
158     protected void cleanupAfterRender(IRequestCycle cycle)
159     {
160         super.cleanupAfterRender(cycle);
161 
162         _pageRenderSupport = null;
163 
164         TapestryUtils.removePageRenderSupport(cycle);
165     }
166 
167     /**
168      * Parameter.
169      */
170     public abstract String   getElement();
171 
172     /**
173      * Injected
174      * 
175      * @since 4.0
176      */
177     public abstract AssetFactory getAssetFactory();
178 
179     /**
180      * Injected
181      * 
182      * @since 4.0
183      */
184 
185     public abstract WebResponse getResponse();
186 
187     /** @since 3.0 */
188 
189     public String   getUniqueString(String   baseValue)
190     {
191         return _pageRenderSupport.getUniqueString(baseValue);
192     }
193 
194 }
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags