1 /* 2 * Copyright (c) 2000, 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 package javax.imageio; 27 28 /** 29 * An interface to be implemented by objects that can determine the 30 * settings of an {@code IIOParam} object, either by putting up a 31 * GUI to obtain values from a user, or by other means. This 32 * interface merely specifies a generic {@code activate} 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} method, a controller obtains 39 * initial values by querying the {@code IIOParam} object's 40 * {@code get} methods, modifies values by whatever means, then 41 * invokes the {@code IIOParam} object's {@code set} methods 42 * to modify the appropriate settings. Normally, these 43 * {@code set} methods will be invoked all at once at a final 44 * commit in order that a cancel operation not disturb existing 45 * values. In general, applications may expect that when the 46 * {@code activate} method returns {@code true}, the 47 * {@code IIOParam} object is ready for use in a read or write 48 * operation. 49 * 50 * <p> Vendors may choose to provide GUIs for the 51 * {@code IIOParam} subclasses they define for a particular 52 * plug-in. These can be set up as default controllers in the 53 * corresponding {@code IIOParam} subclasses. 54 * 55 * <p> Applications may override any default GUIs and provide their 56 * own controllers embedded in their own framework. All that is 57 * required is that the {@code activate} method behave modally 58 * (not returning until either cancelled or committed), though it need 59 * not put up an explicitly modal dialog. Such a non-modal GUI 60 * component would be coded roughly as follows: 61 * 62 * <br> 63 * <pre> 64 * class MyGUI extends SomeComponent implements IIOParamController { 65 * 66 * public MyGUI() { 67 * // ... 68 * setEnabled(false); 69 * } 70 * 71 * public boolean activate(IIOParam param) { 72 * // disable other components if desired 73 * setEnabled(true); 74 * // go to sleep until either cancelled or committed 75 * boolean ret = false; 76 * if (!cancelled) { 77 * // set values on param 78 * ret = true; 79 * } 80 * setEnabled(false); 81 * // enable any components disabled above 82 * return ret; 83 * } 84 * </pre> 85 * 86 * <p> Alternatively, an algorithmic process such as a database lookup 87 * or the parsing of a command line could be used as a controller, in 88 * which case the {@code activate} method would simply look up or 89 * compute the settings, call the {@code IIOParam.setXXX} 90 * methods, and return {@code true}. 91 * 92 * @see IIOParam#setController 93 * @see IIOParam#getController 94 * @see IIOParam#getDefaultController 95 * @see IIOParam#hasController 96 * @see IIOParam#activateController 97 * 98 */ 99 public interface IIOParamController { 100 101 /** 102 * Activates the controller. If {@code true} is returned, 103 * all settings in the {@code IIOParam} object should be 104 * ready for use in a read or write operation. If 105 * {@code false} is returned, no settings in the 106 * {@code IIOParam} object will be disturbed (<i>i.e.</i>, 107 * the user canceled the operation). 108 * 109 * @param param the {@code IIOParam} object to be modified. 110 * 111 * @return {@code true} if the {@code IIOParam} has been 112 * modified, {@code false} otherwise. 113 * 114 * @exception IllegalArgumentException if {@code param} is 115 * {@code null} or is not an instance of the correct class. 116 */ 117 boolean activate(IIOParam param); 118 }