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 import org.apache.tapestry.components.LinkEventType; 031 032 /** 033 * Combines a link component (such as {@link org.apache.tapestry.link.DirectLink}) with an 034 * <img> and 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 </a>] 037 * 038 * @author Howard Lewis Ship 039 */ 040 041 public abstract class Rollover extends AbstractComponent 042 { 043 /** 044 * Converts an {@link IAsset}binding into a usable URL. Returns null if the binding does not 045 * exist or the binding's value is null. 046 */ 047 048 protected String getAssetURL(IAsset asset) 049 { 050 if (asset == null) 051 return null; 052 053 return asset.buildURL(); 054 } 055 056 protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) 057 { 058 // No body, so we skip it all if not rewinding (assumes no side effects on 059 // accessors). 060 061 if (cycle.isRewinding()) 062 return; 063 064 String imageURL = null; 065 String mouseOverURL = null; 066 String mouseOutURL = null; 067 boolean dynamic = false; 068 String imageId = null; 069 070 PageRenderSupport pageRenderSupport = TapestryUtils.getPageRenderSupport(cycle, this); 071 072 ILinkComponent serviceLink = (ILinkComponent) cycle 073 .getAttribute(Tapestry.LINK_COMPONENT_ATTRIBUTE_NAME); 074 075 if (serviceLink == null) 076 throw new ApplicationRuntimeException(Tapestry 077 .getMessage("Rollover.must-be-contained-by-link"), this, null, null); 078 079 boolean linkDisabled = serviceLink.isDisabled(); 080 081 if (linkDisabled) 082 { 083 imageURL = getAssetURL(getDisabled()); 084 085 if (imageURL == null) 086 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, 128 ILinkComponent link, String mouseOverImageURL, String mouseOutImageURL) 129 { 130 String imageId = pageRenderSupport.getUniqueString(getId()); 131 String preloadedMouseOverImageURL = pageRenderSupport 132 .getPreloadedImageReference(mouseOverImageURL); 133 String preloadedMouseOutImageURL = pageRenderSupport 134 .getPreloadedImageReference(mouseOutImageURL); 135 136 Map symbols = new HashMap(); 137 138 symbols.put("imageId", imageId); 139 symbols.put("mouseOverImageURL", preloadedMouseOverImageURL); 140 symbols.put("mouseOutImageURL", preloadedMouseOutImageURL); 141 142 getScript().execute(cycle, pageRenderSupport, symbols); 143 144 // Add attributes to the link to control mouse over/out. 145 // Because the script is written before the <body> tag, 146 // there won't be any timing issues (such as cause 147 // bug #113893). 148 149 link.addEventHandler(LinkEventType.MOUSE_OVER, (String) symbols.get("onMouseOverName")); 150 link.addEventHandler(LinkEventType.MOUSE_OUT, (String) symbols.get("onMouseOutName")); 151 152 return imageId; 153 } 154 155 public abstract IAsset getMouseOut(); 156 157 public abstract IAsset getDisabled(); 158 159 public abstract IAsset getMouseOver(); 160 161 public abstract IAsset getImage(); 162 }