/*
* Copyright 2009 Fred Sauer
*
* 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.allen_sauer.gwt.dnd.client;
import java.util.EventListener;
/**
* {@link EventListener} interface for drag-and-drop events.
*/
public interface DragHandler extends EventListener {
/**
* Fired when drag operation terminates.
*
* @param event an event object containing information about the drag operation
*/
void onDragEnd(DragEndEvent event);
/**
* Fired when drag is initiated.
*
* @param event an event object containing information about the drag operation
*/
void onDragStart(DragStartEvent event);
/**
* Fired before {@link #onDragEnd(DragEndEvent)} is fired and provides an opportunity for any
* registered DragHandler to throw {@link VetoDragException} to prevent the operation.
*
* @param event an event object containing information about the drag operation
* @throws VetoDragException when the drag operation is unacceptable
*/
void onPreviewDragEnd(DragEndEvent event) throws VetoDragException;
/**
* Fired before {@link #onDragStart(DragStartEvent)} is fired and provides an opportunity for any
* registered DragHandler to throw {@link VetoDragException} to prevent the operation.
*
* @param event an event object containing information about the drag operation
* @throws VetoDragException when the drag operation is unacceptable
*/
void onPreviewDragStart(DragStartEvent event) throws VetoDragException;
}