01 /*
02 * Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
03 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04 *
05 * This code is free software; you can redistribute it and/or modify it
06 * under the terms of the GNU General Public License version 2 only, as
07 * published by the Free Software Foundation. Sun designates this
08 * particular file as subject to the "Classpath" exception as provided
09 * 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 javax.imageio.metadata;
27
28 /**
29 * An interface to be implemented by objects that can determine the
30 * settings of an <code>IIOMetadata</code> object, either by putting
31 * up a GUI to obtain values from a user, or by other means. This
32 * interface merely specifies a generic <code>activate</code> method
33 * that invokes the controller, without regard for how the controller
34 * obtains values (<i>i.e.</i>, whether the controller puts up a GUI
35 * or merely computes a set of values is irrelevant to this
36 * interface).
37 *
38 * <p> Within the <code>activate</code> method, a controller obtains
39 * initial values by querying the <code>IIOMetadata</code> object's
40 * settings, either using the XML DOM tree or a plug-in specific
41 * interface, modifies values by whatever means, then modifies the
42 * <code>IIOMetadata</code> object's settings, using either the
43 * <code>setFromTree</code> or <code>mergeTree</code> methods, or a
44 * plug-in specific interface. In general, applications may expect
45 * that when the <code>activate</code> method returns
46 * <code>true</code>, the <code>IIOMetadata</code> object is ready for
47 * use in a write operation.
48 *
49 * <p> Vendors may choose to provide GUIs for the
50 * <code>IIOMetadata</code> subclasses they define for a particular
51 * plug-in. These can be set up as default controllers in the
52 * corresponding <code>IIOMetadata</code> subclasses.
53 *
54 * <p> Alternatively, an algorithmic process such as a database lookup
55 * or the parsing of a command line could be used as a controller, in
56 * which case the <code>activate</code> method would simply look up or
57 * compute the settings, call methods on <code>IIOMetadata</code> to
58 * set its state, and return <code>true</code>.
59 *
60 * @see IIOMetadata#setController
61 * @see IIOMetadata#getController
62 * @see IIOMetadata#getDefaultController
63 * @see IIOMetadata#hasController
64 * @see IIOMetadata#activateController
65 *
66 * @version 0.5
67 */
68 public interface IIOMetadataController {
69
70 /**
71 * Activates the controller. If <code>true</code> is returned,
72 * all settings in the <code>IIOMetadata</code> object should be
73 * ready for use in a write operation. If <code>false</code> is
74 * returned, no settings in the <code>IIOMetadata</code> object
75 * will be disturbed (<i>i.e.</i>, the user canceled the
76 * operation).
77 *
78 * @param metadata the <code>IIOMetadata</code> object to be modified.
79 *
80 * @return <code>true</code> if the <code>IIOMetadata</code> has been
81 * modified, <code>false</code> otherwise.
82 *
83 * @exception IllegalArgumentException if <code>metadata</code> is
84 * <code>null</code> or is not an instance of the correct class.
85 */
86 boolean activate(IIOMetadata metadata);
87 }
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