| /* |
| * Copyright 2002,2004 The Apache Software Foundation. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.jelly.tags.swing; |
| |
| import java.awt.Component; |
| import java.awt.LayoutManager; |
| |
| import org.apache.commons.jelly.JellyTagException; |
| import org.apache.commons.jelly.TagSupport; |
| import org.apache.commons.jelly.XMLOutput; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| /** |
| * An abstract base class used for concrete layout tags which create new LayoutManager implementations |
| * and either export them as variables or set them on parent widgets. |
| * |
| * @author <a href="mailto:jstrachan@apache.org">James Strachan</a> |
| * @version $Revision: 1.7 $ |
| */ |
| public abstract class LayoutTagSupport extends TagSupport { |
| |
| /** The Log to which logging calls will be made. */ |
| private static final Log log = LogFactory.getLog(LayoutTagSupport.class); |
| |
| private String var; |
| |
| public LayoutTagSupport() { |
| } |
| |
| /** |
| * Adds the given layout component to the container with the specified constraints |
| */ |
| public void addLayoutComponent(Component component, Object constraints) throws JellyTagException { |
| getComponentTag().addChild(component, constraints); |
| } |
| |
| |
| // Tag interface |
| //------------------------------------------------------------------------- |
| public void doTag(final XMLOutput output) throws JellyTagException { |
| |
| LayoutManager layout = createLayoutManager(); |
| |
| if (var != null) { |
| context.setVariable(var, layout); |
| } |
| |
| getComponentTag().setLayout(layout); |
| |
| // allow some nested tags to set properties |
| invokeBody(output); |
| } |
| |
| // Properties |
| //------------------------------------------------------------------------- |
| |
| |
| /** |
| * Sets the name of the variable to use to expose the new LayoutManager object. |
| * If this attribute is not set then the parent widget tag will have its |
| * layout property set. |
| */ |
| public void setVar(String var) { |
| this.var = var; |
| } |
| |
| // Implementation methods |
| //------------------------------------------------------------------------- |
| |
| /** |
| * @return the parent component tag or throw an exception |
| */ |
| protected ComponentTag getComponentTag() throws JellyTagException { |
| ComponentTag tag = (ComponentTag) findAncestorWithClass( ComponentTag.class ); |
| if ( tag == null ) { |
| throw new JellyTagException( "This tag must be nested within a JellySwing widget tag" ); |
| } |
| return tag; |
| } |
| |
| /** |
| * Factory method to create a new LayoutManager instance. |
| */ |
| protected abstract LayoutManager createLayoutManager(); |
| } |