vaadin-framework/server/src/main/java/com/vaadin/ui/SelectiveRenderer.java

/*
 * Copyright 2000-2016 Vaadin Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.vaadin.ui;

/**
 * Interface implemented by {@link HasComponents} implementors that wish to
 * dynamically be able to prevent given child components from reaching the
 * client side.
 *
 * @author Vaadin Ltd
 * @since 7.0
 *
 */
public interface SelectiveRenderer extends HasComponents {
    /**
     * Checks if the child component should be rendered (sent to the client
     * side). This method allows hiding a child component from updates and
     * communication to and from the client. It is mostly useful for parents
     * which show only a limited number of their children at any given time and
     * want to allow updates only for the visible children (e.g. TabSheet has
     * one tab open at a time).
     * <p>
     * This method can only prevent updates from reaching the client, not force
     * child components to reach the client. If the child is set to visible,
     * returning false will prevent the child from being sent to the client. If
     * a child is set to invisible, this method has no effect.
     * </p>
     *
     * @param childComponent
     *            The child component to check
     * @return true if the child component may be sent to the client, false
     *         otherwise
     */
    public boolean isRendered(Component childComponent);

}