001 // Copyright 2009, 2011 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.tapestry5.corelib.mixins;
016
017 import org.apache.tapestry5.MarkupWriter;
018 import org.apache.tapestry5.annotations.MixinAfter;
019 import org.apache.tapestry5.dom.Element;
020
021 /**
022 * A mixin that attaches to an element that renders an element. At the end of the render, if the element is empty, then
023 * a non-breaking space ( ) is injected into the element. This is often necessary for proper rendering on the
024 * client.
025 * <p/>
026 * Often used in conjunction with the {@link org.apache.tapestry5.corelib.components.Any} component.
027 *
028 * @since 5.1.0.0
029 * @tapestrydoc
030 */
031 @MixinAfter
032 public class NotEmpty
033 {
034 private Element element;
035
036 void beginRender(MarkupWriter writer)
037 {
038 element = writer.getElement();
039 }
040
041 void afterRender()
042 {
043 if (element.isEmpty())
044 {
045 element.removeChildren();
046 element.raw(" ");
047 }
048 }
049 }