001 // Copyright 2004, 2005 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.tapestry; 016 017 import org.apache.commons.logging.Log; 018 import org.apache.commons.logging.LogFactory; 019 import org.apache.tapestry.engine.IPageLoader; 020 import org.apache.tapestry.spec.IComponentSpecification; 021 022 /** 023 * Base implementation for most components that use an HTML template. 024 * 025 * @author Howard Lewis Ship 026 */ 027 028 public class BaseComponent extends AbstractComponent implements ITemplateComponent 029 { 030 private static final Log LOG = LogFactory.getLog(BaseComponent.class); 031 032 private static final int OUTER_INIT_SIZE = 5; 033 034 private IRender[] _outer; 035 036 private int _outerCount = 0; 037 038 /** 039 * Adds an element as an outer element for the receiver. Outer elements are elements that should 040 * be directly rendered by the receiver's <code>render()</code> method. That is, they are 041 * top-level elements on the HTML template. 042 */ 043 044 public void addOuter(IRender element) 045 { 046 if (_outer == null) 047 { 048 _outer = new IRender[OUTER_INIT_SIZE]; 049 _outer[0] = element; 050 051 _outerCount = 1; 052 return; 053 } 054 055 // No more room? Make the array bigger. 056 057 if (_outerCount == _outer.length) 058 { 059 IRender[] newOuter; 060 061 newOuter = new IRender[_outer.length * 2]; 062 063 System.arraycopy(_outer, 0, newOuter, 0, _outerCount); 064 065 _outer = newOuter; 066 } 067 068 _outer[_outerCount++] = element; 069 } 070 071 /** 072 * Reads the receiver's template and figures out which elements wrap which other elements. 073 */ 074 075 private void readTemplate(IRequestCycle cycle, IPageLoader loader) 076 { 077 loader.loadTemplateForComponent(cycle, this); 078 } 079 080 /** 081 * Renders the top level components contained by the receiver. 082 * 083 * @since 2.0.3 084 */ 085 086 protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) 087 { 088 if (LOG.isDebugEnabled()) 089 LOG.debug("Begin render " + getExtendedId()); 090 091 for (int i = 0; i < _outerCount; i++) 092 _outer[i].render(writer, cycle); 093 094 if (LOG.isDebugEnabled()) 095 LOG.debug("End render " + getExtendedId()); 096 } 097 098 /** 099 * 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 }