001    // Copyright 2004, 2005 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.tapestry.wml;
016    
017    import org.apache.hivemind.HiveMind;
018    import org.apache.tapestry.AbstractComponent;
019    import org.apache.tapestry.IMarkupWriter;
020    import org.apache.tapestry.IRequestCycle;
021    
022    /**
023     * The do element provides a general mechanism for the user to act upon the current card, in other
024     * words a card-level user interface element. The representation of the do element is user agent
025     * dependent and the author must only assume that the element is mapped to a unique user interface
026     * widget that the user can activate. For example, the widget mapping may be to a graphically
027     * rendered button, a soft or function key, a voice-activated command sequence, or any other
028     * interface that has a simple "activate" operation with no inter-operation persistent state. The do
029     * element may appear at both the card and deck-level.
030     * 
031     * @author David Solis
032     * @since 3.0
033     */
034    
035    public abstract class Do extends AbstractComponent
036    {
037        /**
038         * @see AbstractComponent#renderComponent(IMarkupWriter, IRequestCycle)
039         */
040    
041        protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
042        {
043            boolean render = !cycle.isRewinding();
044    
045            if (render)
046            {
047                writer.begin("do");
048    
049                writer.attribute("type", getType());
050    
051                String label = getLabel();
052                if (HiveMind.isNonBlank(label))
053                    writer.attribute("label", label);
054    
055                renderInformalParameters(writer, cycle);
056            }
057    
058            renderBody(writer, cycle);
059    
060            if (render)
061                writer.end();
062        }
063    
064        public abstract String getType();
065    
066        public abstract String getLabel();
067    }