001    // Copyright 2007, 2008 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;
016    
017    import org.apache.tapestry5.dom.Element;
018    
019    /**
020     * An object responsible for performing decorations around fields and field labels. The decorator is notified at
021     * intervals by the fields and labels.
022     * <p/>
023     * In most western languages (written left to right) the label will render before the field, so the properties of the
024     * Field may not be set yet (or may reflect a previous looping's rendering). It may be necessary to {@linkplain
025     * org.apache.tapestry5.services.Heartbeat#defer(Runnable)} defer any rendering} until after the Label and the Field have
026     * both had their change to initialize and render.
027     */
028    public interface ValidationDecorator
029    {
030        /**
031         * Invoked by a {@link org.apache.tapestry5.corelib.components.Label} before rendering itself.
032         *
033         * @param field for this label
034         */
035        void beforeLabel(Field field);
036    
037        /**
038         * Invoked after the label has rendered its tag, but before it has rendered content inside the tag, to allow the
039         * decorator to write additional attributes.
040         *
041         * @param field        the field corresponding to the label
042         * @param labelElement the element for this label
043         */
044        void insideLabel(Field field, Element labelElement);
045    
046    
047        /**
048         * Invoked by {@link org.apache.tapestry5.corelib.components.Label} after rendering itself.
049         *
050         * @param field
051         */
052        void afterLabel(Field field);
053    
054        /**
055         * Renders immediately before the field itself. The field will typically render a single element, though a complex
056         * field may render multiple elements or even some JavaScript.
057         *
058         * @param field
059         */
060        void beforeField(Field field);
061    
062        /**
063         * Invoked at a point where the decorator may write additional attributes into the field. Generally speaking, you
064         * will want to {@linkplain ComponentResources#renderInformalParameters(MarkupWriter) render informal parameters}
065         * <strong>before</strong> invoking this method.
066         *
067         * @param field
068         */
069        void insideField(Field field);
070    
071        /**
072         * Invoked after the field has completed rendering itself.
073         */
074        void afterField(Field field);
075    }