/*
 * Copyright 2011 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.event.dd;

import java.util.Map;

import com.vaadin.ui.Component;

/**
 * DropTarget is an interface for components supporting drop operations. A
 * component that wants to receive drop events should implement this interface
 * and provide a {@link DropHandler} which will handle the actual drop event.
 * 
 * @since 6.3
 */
public interface DropTarget extends Component {

    /**
     * @return the drop hanler that will receive the dragged data or null if
     *         drops are not currently accepted
     */
    public DropHandler getDropHandler();

    /**
     * Called before the {@link DragAndDropEvent} is passed to
     * {@link DropHandler}. Implementation may for example translate the drop
     * target details provided by the client side (drop target) to meaningful
     * server side values. If null is returned the terminal implementation will
     * automatically create a {@link TargetDetails} with raw client side data.
     * 
     * @see DragSource#getTransferable(Map)
     * 
     * @param clientVariables
     *            data passed from the DropTargets client side counterpart.
     * @return A DropTargetDetails object with the translated data or null to
     *         use a default implementation.
     */
    public TargetDetails translateDropTargetDetails(
            Map<String, Object> clientVariables);

}