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src/java.desktop/share/classes/java/awt/dnd/DropTargetListener.java

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  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.awt.dnd;
  27 
  28 import java.util.EventListener;
  29 
  30 import java.awt.dnd.DropTargetDragEvent;
  31 import java.awt.dnd.DropTargetDropEvent;
  32 
  33 /**
  34  * The <code>DropTargetListener</code> interface
  35  * is the callback interface used by the
  36  * <code>DropTarget</code> class to provide
  37  * notification of DnD operations that involve
  38  * the subject <code>DropTarget</code>. Methods of
  39  * this interface may be implemented to provide
  40  * "drag under" visual feedback to the user throughout
  41  * the Drag and Drop operation.
  42  * <p>
  43  * Create a listener object by implementing the interface and then register it
  44  * with a <code>DropTarget</code>. When the drag enters, moves over, or exits
  45  * the operable part of the drop site for that <code>DropTarget</code>, when
  46  * the drop action changes, and when the drop occurs, the relevant method in
  47  * the listener object is invoked, and the <code>DropTargetEvent</code> is
  48  * passed to it.
  49  * <p>
  50  * The operable part of the drop site for the <code>DropTarget</code> is
  51  * the part of the associated <code>Component</code>'s geometry that is not
  52  * obscured by an overlapping top-level window or by another
  53  * <code>Component</code> higher in the Z-order that has an associated active
  54  * <code>DropTarget</code>.
  55  * <p>
  56  * During the drag, the data associated with the current drag operation can be
  57  * retrieved by calling <code>getTransferable()</code> on
  58  * <code>DropTargetDragEvent</code> instances passed to the listener's
  59  * methods.
  60  * <p>
  61  * Note that <code>getTransferable()</code> on the
  62  * <code>DropTargetDragEvent</code> instance should only be called within the
  63  * respective listener's method and all the necessary data should be retrieved
  64  * from the returned <code>Transferable</code> before that method returns.
  65  *
  66  * @since 1.2
  67  */
  68 
  69 public interface DropTargetListener extends EventListener {
  70 
  71     /**
  72      * Called while a drag operation is ongoing, when the mouse pointer enters
  73      * the operable part of the drop site for the <code>DropTarget</code>
  74      * registered with this listener.
  75      *
  76      * @param dtde the <code>DropTargetDragEvent</code>
  77      */
  78 
  79     void dragEnter(DropTargetDragEvent dtde);
  80 
  81     /**
  82      * Called when a drag operation is ongoing, while the mouse pointer is still
  83      * over the operable part of the drop site for the <code>DropTarget</code>
  84      * registered with this listener.
  85      *
  86      * @param dtde the <code>DropTargetDragEvent</code>
  87      */
  88 
  89     void dragOver(DropTargetDragEvent dtde);
  90 
  91     /**
  92      * Called if the user has modified
  93      * the current drop gesture.
  94      *
  95      * @param dtde the <code>DropTargetDragEvent</code>
  96      */
  97 
  98     void dropActionChanged(DropTargetDragEvent dtde);
  99 
 100     /**
 101      * Called while a drag operation is ongoing, when the mouse pointer has
 102      * exited the operable part of the drop site for the
 103      * <code>DropTarget</code> registered with this listener.
 104      *
 105      * @param dte the <code>DropTargetEvent</code>
 106      */
 107 
 108     void dragExit(DropTargetEvent dte);
 109 
 110     /**
 111      * Called when the drag operation has terminated with a drop on
 112      * the operable part of the drop site for the <code>DropTarget</code>
 113      * registered with this listener.
 114      * <p>
 115      * This method is responsible for undertaking
 116      * the transfer of the data associated with the
 117      * gesture. The <code>DropTargetDropEvent</code>
 118      * provides a means to obtain a <code>Transferable</code>
 119      * object that represents the data object(s) to
 120      * be transferred.<P>
 121      * From this method, the <code>DropTargetListener</code>
 122      * shall accept or reject the drop via the
 123      * acceptDrop(int dropAction) or rejectDrop() methods of the
 124      * <code>DropTargetDropEvent</code> parameter.
 125      * <P>
 126      * Subsequent to acceptDrop(), but not before,
 127      * <code>DropTargetDropEvent</code>'s getTransferable()
 128      * method may be invoked, and data transfer may be
 129      * performed via the returned <code>Transferable</code>'s
 130      * getTransferData() method.
 131      * <P>
 132      * At the completion of a drop, an implementation
 133      * of this method is required to signal the success/failure
 134      * of the drop by passing an appropriate
 135      * <code>boolean</code> to the <code>DropTargetDropEvent</code>'s
 136      * dropComplete(boolean success) method.
 137      * <P>
 138      * Note: The data transfer should be completed before the call  to the
 139      * <code>DropTargetDropEvent</code>'s dropComplete(boolean success) method.
 140      * After that, a call to the getTransferData() method of the
 141      * <code>Transferable</code> returned by
 142      * <code>DropTargetDropEvent.getTransferable()</code> is guaranteed to
 143      * succeed only if the data transfer is local; that is, only if
 144      * <code>DropTargetDropEvent.isLocalTransfer()</code> returns
 145      * <code>true</code>. Otherwise, the behavior of the call is
 146      * implementation-dependent.
 147      *
 148      * @param dtde the <code>DropTargetDropEvent</code>
 149      */
 150 
 151     void drop(DropTargetDropEvent dtde);
 152 }


  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.awt.dnd;
  27 
  28 import java.util.EventListener;
  29 
  30 import java.awt.dnd.DropTargetDragEvent;
  31 import java.awt.dnd.DropTargetDropEvent;
  32 
  33 /**
  34  * The {@code DropTargetListener} interface
  35  * is the callback interface used by the
  36  * {@code DropTarget} class to provide
  37  * notification of DnD operations that involve
  38  * the subject {@code DropTarget}. Methods of
  39  * this interface may be implemented to provide
  40  * "drag under" visual feedback to the user throughout
  41  * the Drag and Drop operation.
  42  * <p>
  43  * Create a listener object by implementing the interface and then register it
  44  * with a {@code DropTarget}. When the drag enters, moves over, or exits
  45  * the operable part of the drop site for that {@code DropTarget}, when
  46  * the drop action changes, and when the drop occurs, the relevant method in
  47  * the listener object is invoked, and the {@code DropTargetEvent} is
  48  * passed to it.
  49  * <p>
  50  * The operable part of the drop site for the {@code DropTarget} is
  51  * the part of the associated {@code Component}'s geometry that is not
  52  * obscured by an overlapping top-level window or by another
  53  * {@code Component} higher in the Z-order that has an associated active
  54  * {@code DropTarget}.
  55  * <p>
  56  * During the drag, the data associated with the current drag operation can be
  57  * retrieved by calling {@code getTransferable()} on
  58  * {@code DropTargetDragEvent} instances passed to the listener's
  59  * methods.
  60  * <p>
  61  * Note that {@code getTransferable()} on the
  62  * {@code DropTargetDragEvent} instance should only be called within the
  63  * respective listener's method and all the necessary data should be retrieved
  64  * from the returned {@code Transferable} before that method returns.
  65  *
  66  * @since 1.2
  67  */
  68 
  69 public interface DropTargetListener extends EventListener {
  70 
  71     /**
  72      * Called while a drag operation is ongoing, when the mouse pointer enters
  73      * the operable part of the drop site for the {@code DropTarget}
  74      * registered with this listener.
  75      *
  76      * @param dtde the {@code DropTargetDragEvent}
  77      */
  78 
  79     void dragEnter(DropTargetDragEvent dtde);
  80 
  81     /**
  82      * Called when a drag operation is ongoing, while the mouse pointer is still
  83      * over the operable part of the drop site for the {@code DropTarget}
  84      * registered with this listener.
  85      *
  86      * @param dtde the {@code DropTargetDragEvent}
  87      */
  88 
  89     void dragOver(DropTargetDragEvent dtde);
  90 
  91     /**
  92      * Called if the user has modified
  93      * the current drop gesture.
  94      *
  95      * @param dtde the {@code DropTargetDragEvent}
  96      */
  97 
  98     void dropActionChanged(DropTargetDragEvent dtde);
  99 
 100     /**
 101      * Called while a drag operation is ongoing, when the mouse pointer has
 102      * exited the operable part of the drop site for the
 103      * {@code DropTarget} registered with this listener.
 104      *
 105      * @param dte the {@code DropTargetEvent}
 106      */
 107 
 108     void dragExit(DropTargetEvent dte);
 109 
 110     /**
 111      * Called when the drag operation has terminated with a drop on
 112      * the operable part of the drop site for the {@code DropTarget}
 113      * registered with this listener.
 114      * <p>
 115      * This method is responsible for undertaking
 116      * the transfer of the data associated with the
 117      * gesture. The {@code DropTargetDropEvent}
 118      * provides a means to obtain a {@code Transferable}
 119      * object that represents the data object(s) to
 120      * be transferred.<P>
 121      * From this method, the {@code DropTargetListener}
 122      * shall accept or reject the drop via the
 123      * acceptDrop(int dropAction) or rejectDrop() methods of the
 124      * {@code DropTargetDropEvent} parameter.
 125      * <P>
 126      * Subsequent to acceptDrop(), but not before,
 127      * {@code DropTargetDropEvent}'s getTransferable()
 128      * method may be invoked, and data transfer may be
 129      * performed via the returned {@code Transferable}'s
 130      * getTransferData() method.
 131      * <P>
 132      * At the completion of a drop, an implementation
 133      * of this method is required to signal the success/failure
 134      * of the drop by passing an appropriate
 135      * {@code boolean} to the {@code DropTargetDropEvent}'s
 136      * dropComplete(boolean success) method.
 137      * <P>
 138      * Note: The data transfer should be completed before the call  to the
 139      * {@code DropTargetDropEvent}'s dropComplete(boolean success) method.
 140      * After that, a call to the getTransferData() method of the
 141      * {@code Transferable} returned by
 142      * {@code DropTargetDropEvent.getTransferable()} is guaranteed to
 143      * succeed only if the data transfer is local; that is, only if
 144      * {@code DropTargetDropEvent.isLocalTransfer()} returns
 145      * {@code true}. Otherwise, the behavior of the call is
 146      * implementation-dependent.
 147      *
 148      * @param dtde the {@code DropTargetDropEvent}
 149      */
 150 
 151     void drop(DropTargetDropEvent dtde);
 152 }
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