1/*
2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 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
26package java.awt.dnd;
27
28import java.awt.Point;
29
30import java.util.EventObject;
31
32/**
33 * This class is the base class for
34 * {@code DragSourceDragEvent} and
35 * {@code DragSourceDropEvent}.
36 * <p>
37 * {@code DragSourceEvent}s are generated whenever the drag enters, moves
38 * over, or exits a drop site, when the drop action changes, and when the drag
39 * ends. The location for the generated {@code DragSourceEvent} specifies
40 * the mouse cursor location in screen coordinates at the moment this event
41 * occurred.
42 * <p>
43 * In a multi-screen environment without a virtual device, the cursor location is
44 * specified in the coordinate system of the <i>initiator</i>
45 * {@code GraphicsConfiguration}. The <i>initiator</i>
46 * {@code GraphicsConfiguration} is the {@code GraphicsConfiguration}
47 * of the {@code Component} on which the drag gesture for the current drag
48 * operation was recognized. If the cursor location is outside the bounds of
49 * the initiator {@code GraphicsConfiguration}, the reported coordinates are
50 * clipped to fit within the bounds of that {@code GraphicsConfiguration}.
51 * <p>
52 * In a multi-screen environment with a virtual device, the location is specified
53 * in the corresponding virtual coordinate system. If the cursor location is
54 * outside the bounds of the virtual device the reported coordinates are
55 * clipped to fit within the bounds of the virtual device.
56 *
57 * @since 1.2
58 */
59
60public class DragSourceEvent extends EventObject {
61
62    private static final long serialVersionUID = -763287114604032641L;
63
64    /**
65     * The {@code boolean} indicating whether the cursor location
66     * is specified for this event.
67     *
68     * @serial
69     */
70    private final boolean locationSpecified;
71
72    /**
73     * The horizontal coordinate for the cursor location at the moment this
74     * event occurred if the cursor location is specified for this event;
75     * otherwise zero.
76     *
77     * @serial
78     */
79    private final int x;
80
81    /**
82     * The vertical coordinate for the cursor location at the moment this event
83     * occurred if the cursor location is specified for this event;
84     * otherwise zero.
85     *
86     * @serial
87     */
88    private final int y;
89
90    /**
91     * Construct a {@code DragSourceEvent}
92     * given a specified {@code DragSourceContext}.
93     * The coordinates for this {@code DragSourceEvent}
94     * are not specified, so {@code getLocation} will return
95     * {@code null} for this event.
96     *
97     * @param dsc the {@code DragSourceContext}
98     *
99     * @throws IllegalArgumentException if {@code dsc} is {@code null}.
100     *
101     * @see #getLocation
102     */
103
104    public DragSourceEvent(DragSourceContext dsc) {
105        super(dsc);
106        locationSpecified = false;
107        this.x = 0;
108        this.y = 0;
109    }
110
111    /**
112     * Construct a {@code DragSourceEvent} given a specified
113     * {@code DragSourceContext}, and coordinates of the cursor
114     * location.
115     *
116     * @param dsc the {@code DragSourceContext}
117     * @param x   the horizontal coordinate for the cursor location
118     * @param y   the vertical coordinate for the cursor location
119     *
120     * @throws IllegalArgumentException if {@code dsc} is {@code null}.
121     *
122     * @since 1.4
123     */
124    public DragSourceEvent(DragSourceContext dsc, int x, int y) {
125        super(dsc);
126        locationSpecified = true;
127        this.x = x;
128        this.y = y;
129    }
130
131    /**
132     * This method returns the {@code DragSourceContext} that
133     * originated the event.
134     *
135     * @return the {@code DragSourceContext} that originated the event
136     */
137
138    public DragSourceContext getDragSourceContext() {
139        return (DragSourceContext)getSource();
140    }
141
142    /**
143     * This method returns a {@code Point} indicating the cursor
144     * location in screen coordinates at the moment this event occurred, or
145     * {@code null} if the cursor location is not specified for this
146     * event.
147     *
148     * @return the {@code Point} indicating the cursor location
149     *         or {@code null} if the cursor location is not specified
150     * @since 1.4
151     */
152    public Point getLocation() {
153        if (locationSpecified) {
154            return new Point(x, y);
155        } else {
156            return null;
157        }
158    }
159
160    /**
161     * This method returns the horizontal coordinate of the cursor location in
162     * screen coordinates at the moment this event occurred, or zero if the
163     * cursor location is not specified for this event.
164     *
165     * @return an integer indicating the horizontal coordinate of the cursor
166     *         location or zero if the cursor location is not specified
167     * @since 1.4
168     */
169    public int getX() {
170        return x;
171    }
172
173    /**
174     * This method returns the vertical coordinate of the cursor location in
175     * screen coordinates at the moment this event occurred, or zero if the
176     * cursor location is not specified for this event.
177     *
178     * @return an integer indicating the vertical coordinate of the cursor
179     *         location or zero if the cursor location is not specified
180     * @since 1.4
181     */
182    public int getY() {
183        return y;
184    }
185}
186