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.html; 016 017 import java.util.HashMap; 018 import java.util.Map; 019 020 import org.apache.hivemind.ApplicationRuntimeException; 021 import org.apache.tapestry.AbstractComponent; 022 import org.apache.tapestry.IAsset; 023 import org.apache.tapestry.IMarkupWriter; 024 import org.apache.tapestry.IRequestCycle; 025 import org.apache.tapestry.IScript; 026 import org.apache.tapestry.PageRenderSupport; 027 import org.apache.tapestry.Tapestry; 028 import org.apache.tapestry.TapestryUtils; 029 import org.apache.tapestry.components.ILinkComponent; 030 031 /** 032 * Combines a link component (such as 033 * {@link org.apache.tapestry.link.DirectLink}) with an <img> and 034 * JavaScript code to create a rollover effect that works with both Netscape 035 * Navigator and Internet Explorer. [ <a 036 * href="../../../../../ComponentReference/Rollover.html">Component Reference 037 * </a>] 038 * 039 * @author Howard Lewis Ship 040 */ 041 042 public abstract class Rollover extends AbstractComponent 043 { 044 045 /** 046 * Converts an {@link IAsset}binding into a usable URL. Returns null if the 047 * binding does not exist or the binding's value is null. 048 */ 049 050 protected String getAssetURL(IAsset asset) 051 { 052 if (asset == null) return null; 053 054 return asset.buildURL(); 055 } 056 057 protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) 058 { 059 // No body, so we skip it all if not rewinding (assumes no side effects 060 // on 061 // accessors). 062 063 if (cycle.isRewinding()) 064 return; 065 066 String imageURL = null; 067 String mouseOverURL = null; 068 String mouseOutURL = null; 069 boolean dynamic = false; 070 String imageId = null; 071 072 PageRenderSupport pageRenderSupport = TapestryUtils.getPageRenderSupport(cycle, this); 073 074 ILinkComponent serviceLink = (ILinkComponent) cycle.getAttribute(Tapestry.LINK_COMPONENT_ATTRIBUTE_NAME); 075 076 if (serviceLink == null) 077 throw new ApplicationRuntimeException(Tapestry 078 .getMessage("Rollover.must-be-contained-by-link"), this, null, null); 079 080 boolean linkDisabled = serviceLink.isDisabled(); 081 082 if (linkDisabled) 083 { 084 imageURL = getAssetURL(getDisabled()); 085 086 if (imageURL == null) imageURL = getAssetURL(getImage()); 087 } 088 else 089 { 090 imageURL = getAssetURL(getImage()); 091 mouseOverURL = getAssetURL(getMouseOver()); 092 mouseOutURL = getAssetURL(getMouseOut()); 093 094 dynamic = (mouseOverURL != null) || (mouseOutURL != null); 095 } 096 097 if (imageURL == null) 098 throw Tapestry.createRequiredParameterException(this, "image"); 099 100 writer.beginEmpty("img"); 101 102 writer.attribute("src", imageURL); 103 104 if (dynamic) 105 { 106 if (mouseOverURL == null) 107 mouseOverURL = imageURL; 108 109 if (mouseOutURL == null) 110 mouseOutURL = imageURL; 111 112 imageId = writeScript(cycle, pageRenderSupport, serviceLink, mouseOverURL, mouseOutURL); 113 114 writer.attribute("id", imageId); 115 } 116 117 renderInformalParameters(writer, cycle); 118 119 writer.closeTag(); 120 121 } 122 123 // Injected 124 125 public abstract IScript getScript(); 126 127 private String writeScript(IRequestCycle cycle, PageRenderSupport pageRenderSupport, ILinkComponent link, 128 String mouseOverImageURL, String mouseOutImageURL) 129 { 130 String imageId = pageRenderSupport.getUniqueString(getId()); 131 132 String preloadedMouseOverImageURL = pageRenderSupport.getPreloadedImageReference(this, mouseOverImageURL); 133 String preloadedMouseOutImageURL = pageRenderSupport.getPreloadedImageReference(this, mouseOutImageURL); 134 135 Map symbols = new HashMap(); 136 137 symbols.put("link", link); 138 symbols.put("imageId", imageId); 139 symbols.put("mouseOverImageURL", preloadedMouseOverImageURL); 140 symbols.put("mouseOutImageURL", preloadedMouseOutImageURL); 141 142 getScript().execute(this, cycle, pageRenderSupport, symbols); 143 144 return imageId; 145 } 146 147 public abstract IAsset getMouseOut(); 148 149 public abstract IAsset getDisabled(); 150 151 public abstract IAsset getMouseOver(); 152 153 public abstract IAsset getImage(); 154 }