https://openjdk.java.net/ 
/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.awt.dnd;

import java.awt.Point;

import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;

import java.util.List;


The DropTargetDragEvent is delivered to a DropTargetListener via its dragEnter() and dragOver() methods. 
 The DropTargetDragEvent reports the source drop actions
and the user drop action that reflect the current state of
the drag operation.


Source drop actions is a bitwise mask of DnDConstants that represents the set of drop actions supported by the drag source for this drag operation. 

User drop action depends on the drop actions supported by the drag
source and the drop action selected by the user. The user can select a drop
action by pressing modifier keys during the drag operation:

  Ctrl + Shift -> ACTION_LINK
  Ctrl         -> ACTION_COPY
  Shift        -> ACTION_MOVE


If the user selects a drop action, the user drop action is one of DnDConstants that represents the selected drop action if this drop action is supported by the drag source or DnDConstants.ACTION_NONE if this drop action is not supported by the drag source. 
 If the user doesn't select a drop action, the set of DnDConstants that represents the set of drop actions supported by the drag source is searched for DnDConstants.ACTION_MOVE, then for DnDConstants.ACTION_COPY, then for DnDConstants.ACTION_LINK and the user drop action is the
first constant found. If no constant is found the user drop action is DnDConstants.ACTION_NONE. 
Since:1.2
/**
 * The {@code DropTargetDragEvent} is delivered to a
 * {@code DropTargetListener} via its
 * dragEnter() and dragOver() methods.
 * <p>
 * The {@code DropTargetDragEvent} reports the <i>source drop actions</i>
 * and the <i>user drop action</i> that reflect the current state of
 * the drag operation.
 * <p>
 * <i>Source drop actions</i> is a bitwise mask of {@code DnDConstants}
 * that represents the set of drop actions supported by the drag source for
 * this drag operation.
 * <p>
 * <i>User drop action</i> depends on the drop actions supported by the drag
 * source and the drop action selected by the user. The user can select a drop
 * action by pressing modifier keys during the drag operation:
 * <pre>
 *   Ctrl + Shift -&gt; ACTION_LINK
 *   Ctrl         -&gt; ACTION_COPY
 *   Shift        -&gt; ACTION_MOVE
 * </pre>
 * If the user selects a drop action, the <i>user drop action</i> is one of
 * {@code DnDConstants} that represents the selected drop action if this
 * drop action is supported by the drag source or
 * {@code DnDConstants.ACTION_NONE} if this drop action is not supported
 * by the drag source.
 * <p>
 * If the user doesn't select a drop action, the set of
 * {@code DnDConstants} that represents the set of drop actions supported
 * by the drag source is searched for {@code DnDConstants.ACTION_MOVE},
 * then for {@code DnDConstants.ACTION_COPY}, then for
 * {@code DnDConstants.ACTION_LINK} and the <i>user drop action</i> is the
 * first constant found. If no constant is found the <i>user drop action</i>
 * is {@code DnDConstants.ACTION_NONE}.
 *
 * @since 1.2
 */

public class DropTargetDragEvent extends DropTargetEvent {

    private static final long serialVersionUID = -8422265619058953682L;

    
Construct a DropTargetDragEvent given the DropTargetContext for this operation, the location of the "Drag" Cursor's hotspot in the Component's coordinates, the user drop action, and the source drop actions. 
Params:
  • dtc –        The DropTargetContext for this operation
  • cursorLocn – The location of the "Drag" Cursor's
hotspot in Component coordinates
  • dropAction – The user drop action
  • srcActions – The source drop actions
Throws:
/**
     * Construct a {@code DropTargetDragEvent} given the
     * {@code DropTargetContext} for this operation,
     * the location of the "Drag" {@code Cursor}'s hotspot
     * in the {@code Component}'s coordinates, the
     * user drop action, and the source drop actions.
     *
     * @param dtc        The DropTargetContext for this operation
     * @param cursorLocn The location of the "Drag" Cursor's
     * hotspot in Component coordinates
     * @param dropAction The user drop action
     * @param srcActions The source drop actions
     *
     * @throws NullPointerException if cursorLocn is null
     * @throws IllegalArgumentException if dropAction is not one of
     *         {@code DnDConstants}.
     * @throws IllegalArgumentException if srcActions is not
     *         a bitwise mask of {@code DnDConstants}.
     * @throws IllegalArgumentException if dtc is {@code null}.
     */

    public DropTargetDragEvent(DropTargetContext dtc, Point cursorLocn, int dropAction, int srcActions)  {
        super(dtc);

        if (cursorLocn == null) throw new NullPointerException("cursorLocn");

        if (dropAction != DnDConstants.ACTION_NONE &&
            dropAction != DnDConstants.ACTION_COPY &&
            dropAction != DnDConstants.ACTION_MOVE &&
            dropAction != DnDConstants.ACTION_LINK
        ) throw new IllegalArgumentException("dropAction" + dropAction);

        if ((srcActions & ~(DnDConstants.ACTION_COPY_OR_MOVE | DnDConstants.ACTION_LINK)) != 0) throw new IllegalArgumentException("srcActions");

        location        = cursorLocn;
        actions         = srcActions;
        this.dropAction = dropAction;
    }

    
This method returns a Point indicating the Cursor's current location within the Component's coordinates. 
Returns:the current cursor location in Component's coords.
/**
     * This method returns a {@code Point}
     * indicating the {@code Cursor}'s current
     * location within the {@code Component'}s
     * coordinates.
     *
     * @return the current cursor location in
     * {@code Component}'s coords.
     */

    public Point getLocation() {
        return location;
    }


    
This method returns the current DataFlavors from the DropTargetContext. 
Returns:current DataFlavors from the DropTargetContext
/**
     * This method returns the current {@code DataFlavor}s from the
     * {@code DropTargetContext}.
     *
     * @return current DataFlavors from the DropTargetContext
     */

    public DataFlavor[] getCurrentDataFlavors() {
        return getDropTargetContext().getCurrentDataFlavors();
    }

    
This method returns the current DataFlavors as a java.util.List 
Returns:a java.util.List of the Current DataFlavors
/**
     * This method returns the current {@code DataFlavor}s
     * as a {@code java.util.List}
     *
     * @return a {@code java.util.List} of the Current {@code DataFlavor}s
     */

    public List<DataFlavor> getCurrentDataFlavorsAsList() {
        return getDropTargetContext().getCurrentDataFlavorsAsList();
    }

    
This method returns a boolean indicating if the specified DataFlavor is supported. 
Params:
  • df – the DataFlavor to test
Returns:if a particular DataFlavor is supported
/**
     * This method returns a {@code boolean} indicating
     * if the specified {@code DataFlavor} is supported.
     *
     * @param df the {@code DataFlavor} to test
     *
     * @return if a particular DataFlavor is supported
     */

    public boolean isDataFlavorSupported(DataFlavor df) {
        return getDropTargetContext().isDataFlavorSupported(df);
    }

    
This method returns the source drop actions.

Returns:the source drop actions
/**
     * This method returns the source drop actions.
     *
     * @return the source drop actions
     */
    public int getSourceActions() { return actions; }

    
This method returns the user drop action.

Returns:the user drop action
/**
     * This method returns the user drop action.
     *
     * @return the user drop action
     */
    public int getDropAction() { return dropAction; }

    
This method returns the Transferable object that represents
the data associated with the current drag operation.

Throws:
Returns:the Transferable associated with the drag operation
Since:1.5
/**
     * This method returns the Transferable object that represents
     * the data associated with the current drag operation.
     *
     * @return the Transferable associated with the drag operation
     * @throws InvalidDnDOperationException if the data associated with the drag
     *         operation is not available
     *
     * @since 1.5
     */
    public Transferable getTransferable() {
        return getDropTargetContext().getTransferable();
    }

    
Accepts the drag. This method should be called from a DropTargetListeners dragEnter, dragOver, and dropActionChanged methods if the implementation wishes to accept an operation from the srcActions other than the one selected by the user as represented by the dropAction. 
Params:
  • dragOperation – the operation accepted by the target
/**
     * Accepts the drag.
     *
     * This method should be called from a
     * {@code DropTargetListeners dragEnter},
     * {@code dragOver}, and {@code dropActionChanged}
     * methods if the implementation wishes to accept an operation
     * from the srcActions other than the one selected by
     * the user as represented by the {@code dropAction}.
     *
     * @param dragOperation the operation accepted by the target
     */
    public void acceptDrag(int dragOperation) {
        getDropTargetContext().acceptDrag(dragOperation);
    }

    
Rejects the drag as a result of examining either the dropAction or the available DataFlavor types. 
/**
     * Rejects the drag as a result of examining either the
     * {@code dropAction} or the available {@code DataFlavor}
     * types.
     */
    public void rejectDrag() {
        getDropTargetContext().rejectDrag();
    }

    /*
     * fields
     */

    
The location of the drag cursor's hotspot in Component coordinates.

@serial
/**
     * The location of the drag cursor's hotspot in Component coordinates.
     *
     * @serial
     */
    private Point               location;

    
The source drop actions.

@serial
/**
     * The source drop actions.
     *
     * @serial
     */
    private int                 actions;

    
The user drop action.

@serial
/**
     * The user drop action.
     *
     * @serial
     */
    private int                 dropAction;
}