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| 1 | +<!-- | |
| 2 | + Copyright (c) 1998, 1999, 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 | + | |
| 26 | +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> | |
| 27 | +<html> | |
| 28 | +<body bgcolor="white"> | |
| 29 | + | |
| 30 | +Drag and Drop is a direct manipulation gesture found in many Graphical | |
| 31 | +User Interface systems that provides a mechanism to transfer | |
| 32 | +information between two entities logically associated with presentation | |
| 33 | +elements in the GUI. Normally driven by a physical gesture of a | |
| 34 | +human user using an appropriate input device, Drag and Drop provides both | |
| 35 | +a mechanism to enable continuous feedback regarding the | |
| 36 | +possible outcome of any subsequent data transfer to the user during | |
| 37 | +navigation over the presentation elements in the GUI, and the facilities | |
| 38 | +to provide for any subsequent data negotiation and transfer. | |
| 39 | +<P> | |
| 40 | +This package defines the classes and interfaces necessary to perform Drag | |
| 41 | +and Drop operations in Java. It | |
| 42 | +defines classes for the drag-source and the drop-target, as well as | |
| 43 | +events for transferring the data being dragged. This package also provides | |
| 44 | +a means for giving visual feedback to the user throughout the | |
| 45 | +duration of the Drag and Drop operation. | |
| 46 | +<P> | |
| 47 | +A typical Drag and Drop operation can be decomposed into the following | |
| 48 | +states (not entirely sequentially): | |
| 49 | +<UL> | |
| 50 | +<LI>A <code>DragSource</code> comes into existence, | |
| 51 | +associated with some presentation | |
| 52 | +element (<code>Component</code>) in the GUI, to initiate a Drag and Drop of | |
| 53 | +some potentially <code>Transferable</code> data. | |
| 54 | +<P> | |
| 55 | +<LI>1 or more <code>DropTarget</code>(s) come into/go out of | |
| 56 | +existence, associated | |
| 57 | +with presentation elements in the GUI (Components), potentially | |
| 58 | +capable of consuming <code>Transferable</code> data types. | |
| 59 | +<P> | |
| 60 | +<LI> A <code>DragGestureRecognizer</code> is | |
| 61 | +obtained from the <code>DragSource</code> and is | |
| 62 | +associated with a <code>Component</code> in order | |
| 63 | +to track and identify any Drag | |
| 64 | +initiating gesture by the user over the <code>Component</code>. | |
| 65 | +<P> | |
| 66 | +<LI> A user makes a Drag gesture over the <code>Component</code>, | |
| 67 | +which the registered | |
| 68 | +<code>DragGestureRecognizer</code> detects, and notifies its | |
| 69 | +<code>DragGestureListener</code> of. | |
| 70 | +<P> | |
| 71 | +Note: Although this API consistently refers to the stimulus for a | |
| 72 | +drag and drop operation being a physical gesture by a human user, this | |
| 73 | +does not preclude a programmatically driven DnD operation given the | |
| 74 | +appropriate implementation of a <code>DragSource</code>. This package | |
| 75 | +contains the abstract class <code>MouseDragGestureRecognizer</code> for | |
| 76 | +recognizing mouse device gestures. Other abstract subclasses may be | |
| 77 | +provided by the platform to support other input devices or | |
| 78 | +particular <code>Component</code> class semantics. | |
| 79 | + <P> | |
| 80 | +<LI> The <code>DragGestureListener</code> causes the | |
| 81 | +<code>DragSource</code> to initiate the Drag | |
| 82 | +and Drop operation on behalf of the user, perhaps animating the | |
| 83 | +GUI Cursor and/or rendering an <code>Image</code> of the item(s) that are the | |
| 84 | +subject of the operation. | |
| 85 | +<P> | |
| 86 | +<LI> As the user gestures navigate over <code>Component</code>(s) | |
| 87 | +in the GUI with | |
| 88 | +associated <code>DropTarget</code>(s), the <code>DragSource</code> | |
| 89 | +receives notifications in order | |
| 90 | +to provide "Drag Over" feedback effects, and the <code>DropTarget</code>(s) | |
| 91 | +receive notifications in order to provide "Drag Under" feedback effects | |
| 92 | +based upon the operation(s) supported and the data type(s) involved. | |
| 93 | +</UL> | |
| 94 | +<P> | |
| 95 | + | |
| 96 | +The gesture itself moves a logical cursor across the GUI hierarchy, | |
| 97 | +intersecting the geometry of GUI Component(s), possibly resulting in | |
| 98 | +the logical "Drag" cursor entering, crossing, and subsequently | |
| 99 | +leaving <code>Component</code>(s) and associated <code>DropTarget</code>(s). | |
| 100 | +<P> | |
| 101 | +The <code>DragSource</code> object manifests "Drag Over" feedback to the user, in the typical case by animating the GUI <code>Cursor</code> associated with the | |
| 102 | +logical cursor. | |
| 103 | +<P> | |
| 104 | +<code>DropTarget</code> objects manifest "Drag Under" feedback to the user, in | |
| 105 | +the typical case, by rendering animations into their associated GUI | |
| 106 | +<code>Component</code>(s) under the GUI Cursor. | |
| 107 | +<P> | |
| 108 | +The determination of the feedback effects, and the ultimate success | |
| 109 | +or failure of the data transfer, should one occur, is parameterized | |
| 110 | +as follows: | |
| 111 | +<UL> | |
| 112 | +<LI> By the transfer "operation" selected by the user, and supported by | |
| 113 | +both the <code>DragSource</code> and <code>DropTarget</code>: Copy, Move or Reference(link). | |
| 114 | +<P> | |
| 115 | +<LI> By the intersection of the set of data types provided by the | |
| 116 | +<code>DragSource</code> and the set of data types comprehensible by the | |
| 117 | +<code>DropTarget</code>. | |
| 118 | +<P> | |
| 119 | +<LI>When the user terminates the drag operation, normally resulting in a | |
| 120 | +successful Drop, both the <code>DragSource</code> and <code>DropTarget</code> | |
| 121 | +receive | |
| 122 | +notifications that include, and result in the type negotiation and | |
| 123 | +transfer of, the information associated with the <code>DragSource</code> via a | |
| 124 | +<code>Transferable</code> object. | |
| 125 | +</UL> | |
| 126 | + | |
| 127 | +<!-- | |
| 128 | +<h2>Package Specification</h2> | |
| 129 | + | |
| 130 | +##### FILL IN ANY SPECS NEEDED BY JAVA COMPATIBILITY KIT ##### | |
| 131 | +<ul> | |
| 132 | + <li><a href="">##### REFER TO ANY FRAMEMAKER SPECIFICATION HERE #####</a> | |
| 133 | +</ul> | |
| 134 | + | |
| 135 | +<h2>Related Documentation</h2> | |
| 136 | + | |
| 137 | +For overviews, tutorials, examples, guides, and tool documentation, please see: | |
| 138 | +<ul> | |
| 139 | + <li><a href="">##### REFER TO NON-SPEC DOCUMENTATION HERE #####</a> | |
| 140 | +</ul> | |
| 141 | +--> | |
| 142 | + | |
| 143 | +@since 1.2 | |
| 144 | +</body> | |
| 145 | +</html> | |