1 /*
2 * Copyright 1998-1999 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.awt.dnd;
27
28 import java.awt.Insets;
29 import java.awt.Point;
30
31 /**
32 * During DnD operations it is possible that a user may wish to drop the
33 * subject of the operation on a region of a scrollable GUI control that is
34 * not currently visible to the user.
35 * <p>
36 * In such situations it is desirable that the GUI control detect this
37 * and institute a scroll operation in order to make obscured region(s)
38 * visible to the user. This feature is known as autoscrolling.
39 * <p>
40 * If a GUI control is both an active <code>DropTarget</code>
41 * and is also scrollable, it
42 * can receive notifications of autoscrolling gestures by the user from
43 * the DnD system by implementing this interface.
44 * <p>
45 * An autoscrolling gesture is initiated by the user by keeping the drag
46 * cursor motionless with a border region of the <code>Component</code>,
47 * referred to as
48 * the "autoscrolling region", for a predefined period of time, this will
49 * result in repeated scroll requests to the <code>Component</code>
50 * until the drag <code>Cursor</code> resumes its motion.
51 *
52 * @since 1.2
53 */
54
55 public interface Autoscroll {
56
57 /**
58 * This method returns the <code>Insets</code> describing
59 * the autoscrolling region or border relative
60 * to the geometry of the implementing Component.
61 * <P>
62 * This value is read once by the <code>DropTarget</code>
63 * upon entry of the drag <code>Cursor</code>
64 * into the associated <code>Component</code>.
65 * <P>
66 * @return the Insets
67 */
68
69 public Insets getAutoscrollInsets();
70
71 /**
72 * notify the <code>Component</code> to autoscroll
73 * <P>
74 * @param cursorLocn A <code>Point</code> indicating the
75 * location of the cursor that triggered this operation.
76 */
77
78 public void autoscroll(Point cursorLocn);
79
80 }
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