    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 (&amp;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("&nbsp;");
    047        }
    048    }
    049}