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
015package org.apache.tapestry5;
016
017import 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 */
028public 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}