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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> | ||