/* * Copyright (c) 2000, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.imageio; /** * An interface to be implemented by objects that can determine the * settings of an <code>IIOParam</code> object, either by putting up a * GUI to obtain values from a user, or by other means.  This * interface merely specifies a generic <code>activate</code> method * that invokes the controller, without regard for how the controller * obtains values (<i>i.e.</i>, whether the controller puts up a GUI * or merely computes a set of values is irrelevant to this * interface). * * <p> Within the <code>activate</code> method, a controller obtains * initial values by querying the <code>IIOParam</code> object's * <code>get</code> methods, modifies values by whatever means, then * invokes the <code>IIOParam</code> object's <code>set</code> methods * to modify the appropriate settings.  Normally, these * <code>set</code> methods will be invoked all at once at a final * commit in order that a cancel operation not disturb existing * values.  In general, applications may expect that when the * <code>activate</code> method returns <code>true</code>, the * <code>IIOParam</code> object is ready for use in a read or write * operation. * * <p> Vendors may choose to provide GUIs for the * <code>IIOParam</code> subclasses they define for a particular * plug-in.  These can be set up as default controllers in the * corresponding <code>IIOParam</code> subclasses. * * <p> Applications may override any default GUIs and provide their * own controllers embedded in their own framework.  All that is * required is that the<code>activate</code> method behave modally * (not returning until either cancelled or committed), though it need * not put up an explicitly modal dialog.  Such a non-modal GUI * component would be coded roughly as follows: * * <br> * <pre> * class MyGUI extends SomeComponent implements IIOParamController { * *    public MyGUI() { *        // ... *        setEnabled(false); *    } * *    public boolean activate(IIOParam param) { *        // disable other components if desired *        setEnabled(true); *        // go to sleep until either cancelled or committed *        boolean ret = false; *        if (!cancelled) { *            // set values on param *            ret = true; *        } *        setEnabled(false); *        // enable any components disabled above *        return ret; *    } * </pre> * * <p> Alternatively, an algorithmic process such as a database lookup * or the parsing of a command line could be used as a controller, in * which case the <code>activate</code> method would simply look up or * compute the settings, call the <code>IIOParam.setXXX</code> * methods, and return <code>true</code>. * * @see IIOParam#setController * @see IIOParam#getController * @see IIOParam#getDefaultController * @see IIOParam#hasController * @see IIOParam#activateController * */public interface IIOParamController {     /**     * Activates the controller.  If <code>true</code> is returned,     * all settings in the <code>IIOParam</code> object should be     * ready for use in a read or write operation.  If     * <code>false</code> is returned, no settings in the     * <code>IIOParam</code> object will be disturbed (<i>i.e.</i>,     * the user canceled the operation).     *     * @param param the <code>IIOParam</code> object to be modified.     *     * @return <code>true</code> if the <code>IIOParam</code> has been     * modified, <code>false</code> otherwise.     *     * @exception IllegalArgumentException if <code>param</code> is     * <code>null</code> or is not an instance of the correct class.     */    boolean activate(IIOParam param);}