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