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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;
16
17 import org.apache.commons.logging.Log;
18 import org.apache.commons.logging.LogFactory;
19 import org.apache.tapestry.engine.IPageLoader;
20 import org.apache.tapestry.spec.IComponentSpecification;
21
22 /**
23  * Base implementation for most components that use an HTML template.
24  *
25  * @author Howard Lewis Ship
26  */
27
28 public class BaseComponent extends AbstractComponent implements ITemplateComponent
29 {
30     private static final Log LOG = LogFactory.getLog(BaseComponent.class);
31
32     private static final int OUTER_INIT_SIZE = 5;
33
34     private IRender[] _outer;
35
36     private int _outerCount = 0;
37
38     /**
39      * Adds an element as an outer element for the receiver. Outer elements are elements that should
40      * be directly rendered by the receiver's <code>render()</code> method. That is, they are
41      * top-level elements on the HTML template.
42      */
43
44     public void addOuter(IRender element)
45     {
46         if (_outer == null)
47         {
48             _outer = new IRender[OUTER_INIT_SIZE];
49             _outer[0] = element;
50
51             _outerCount = 1;
52             return;
53         }
54
55         // No more room? Make the array bigger.
56
57         if (_outerCount == _outer.length)
58         {
59             IRender[] newOuter;
60
61             newOuter = new IRender[_outer.length * 2];
62
63             System.arraycopy(_outer, 0, newOuter, 0, _outerCount);
64
65             _outer = newOuter;
66         }
67
68         _outer[_outerCount++] = element;
69     }
70
71     /**
72      * Reads the receiver's template and figures out which elements wrap which other elements.
73      */
74
75     private void readTemplate(IRequestCycle cycle, IPageLoader loader)
76     {
77         loader.loadTemplateForComponent(cycle, this);
78     }
79
80     /**
81      * Renders the top level components contained by the receiver.
82      *
83      * @since 2.0.3
84      */
85
86     protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
87     {
88         if (LOG.isDebugEnabled())
89             LOG.debug("Begin render " + getExtendedId());
90
91         for (int i = 0; i < _outerCount; i++)
92             _outer[i].render(writer, cycle);
93
94         if (LOG.isDebugEnabled())
95             LOG.debug("End render " + getExtendedId());
96     }
97
98     /**
99      * Loads the template for the component, then invokes
100      * {@link AbstractComponent#finishLoad(IRequestCycle, IPageLoader, IComponentSpecification)}.
101      * Subclasses must invoke this method first, before adding any additional behavior, though its
102      * usually simpler to override {@link #finishLoad()}instead.
103      */
104
105     public void finishLoad(IRequestCycle cycle, IPageLoader loader, IComponentSpecification specification)
106     {
107         readTemplate(cycle, loader);
108
109         super.finishLoad(cycle, loader, specification);
110     }
111 }
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