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DragSourceAdapter.java
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DragSourceAdapter.java
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/*
* Copyright (c) 2001, 2020, 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;
/**
* An abstract adapter class for receiving drag source events. The methods in
* this class are empty. This class exists only as a convenience for creating
* listener objects.
* <p>
* Extend this class to create a {@code DragSourceEvent} listener
* and override the methods for the events of interest. (If you implement the
* {@code DragSourceListener} interface, you have to define all of
* the methods in it. This abstract class defines null methods for them
* all, so you only have to define methods for events you care about.)
* <p>
* Create a listener object using the extended class and then register it with
* a {@code DragSource}. When the drag enters, moves over, or exits
* a drop site, when the drop action changes, and when the drag ends, the
* relevant method in the listener object is invoked, and the
* {@code DragSourceEvent} is passed to it.
* <p>
* The drop site is <i>associated with the previous {@code dragEnter()}
* invocation</i> if the latest invocation of {@code dragEnter()} on this
* adapter corresponds to that drop site and is not followed by a
* {@code dragExit()} invocation on this adapter.
*
* @see DragSourceEvent
* @see DragSourceListener
* @see DragSourceMotionListener
*
* @author David Mendenhall
* @since 1.4
*/
public abstract class DragSourceAdapter
implements DragSourceListener, DragSourceMotionListener {
/**
* Constructs a {@code DragSourceAdapter}.
*/
protected DragSourceAdapter() {}
/**
* Called as the cursor's hotspot enters a platform-dependent drop site.
* This method is invoked when all the following conditions are true:
* <UL>
* <LI>The cursor's hotspot enters the operable part of
* a platform-dependent drop site.
* <LI>The drop site is active.
* <LI>The drop site accepts the drag.
* </UL>
*
* @param dsde the {@code DragSourceDragEvent}
*/
public void dragEnter(DragSourceDragEvent dsde) {}
/**
* Called as the cursor's hotspot moves over a platform-dependent drop site.
* This method is invoked when all the following conditions are true:
* <UL>
* <LI>The cursor's hotspot has moved, but still intersects the
* operable part of the drop site associated with the previous
* dragEnter() invocation.
* <LI>The drop site is still active.
* <LI>The drop site accepts the drag.
* </UL>
*
* @param dsde the {@code DragSourceDragEvent}
*/
public void dragOver(DragSourceDragEvent dsde) {}
/**
* Called whenever the mouse is moved during a drag operation.
*
* @param dsde the {@code DragSourceDragEvent}
*/
public void dragMouseMoved(DragSourceDragEvent dsde) {}
/**
* Called when the user has modified the drop gesture.
* This method is invoked when the state of the input
* device(s) that the user is interacting with changes.
* Such devices are typically the mouse buttons or keyboard
* modifiers that the user is interacting with.
*
* @param dsde the {@code DragSourceDragEvent}
*/
public void dropActionChanged(DragSourceDragEvent dsde) {}
/**
* Called as the cursor's hotspot exits a platform-dependent drop site.
* This method is invoked when any of the following conditions are true:
* <UL>
* <LI>The cursor's hotspot no longer intersects the operable part
* of the drop site associated with the previous dragEnter() invocation.
* </UL>
* OR
* <UL>
* <LI>The drop site associated with the previous dragEnter() invocation
* is no longer active.
* </UL>
* OR
* <UL>
* <LI> The drop site associated with the previous dragEnter() invocation
* has rejected the drag.
* </UL>
*
* @param dse the {@code DragSourceEvent}
*/
public void dragExit(DragSourceEvent dse) {}
/**
* This method is invoked to signify that the Drag and Drop
* operation is complete. The getDropSuccess() method of
* the {@code DragSourceDropEvent} can be used to
* determine the termination state. The getDropAction() method
* returns the operation that the drop site selected
* to apply to the Drop operation. Once this method is complete, the
* current {@code DragSourceContext} and
* associated resources become invalid.
*
* @param dsde the {@code DragSourceDropEvent}
*/
public void dragDropEnd(DragSourceDropEvent dsde) {}
}