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 015package org.apache.tapestry5.corelib.mixins; 016 017import org.apache.tapestry5.MarkupWriter; 018import org.apache.tapestry5.annotations.MixinAfter; 019import 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 (&nbsp;) 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 032public 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}