001    /* AccessibleValue.java -- aids in accessibly controlling values
002       Copyright (C) 2002, 2005  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.accessibility;
040    
041    /**
042     * If an object implements this interface then it must be able to control
043     * a numerical value. For example, a scroll bar has a position represented
044     * by a number. Accessibility software can use the implementations of this
045     * interface to change the associated value.
046     *
047     * <p>The <code>AccessibleContext.getAccessibleValue()</code> method should
048     * return <code>null</code> if an object does not implement this interface.
049     *
050     * @author Eric Blake (ebb9@email.byu.edu)
051     * @see Accessible
052     * @see AccessibleContext
053     * @see AccessibleContext#getAccessibleValue()
054     * @since 1.2
055     * @status updated to 1.4
056     */
057    public interface AccessibleValue
058    {
059      /**
060       * Gets the current value of this object, or null if it has not been set.
061       *
062       * @return the current value, or null
063       * @see #setCurrentAccessibleValue(Number)
064       */
065      Number getCurrentAccessibleValue();
066    
067      /**
068       * Sets the current value of this object. Returns true if the number
069       * successfully changed.
070       *
071       * @param number the new value
072       * @return true on success
073       */
074      // XXX What happens if number is null?
075      boolean setCurrentAccessibleValue(Number number);
076    
077      /**
078       * Gets the minimum value in the range of this object, or null if there is
079       * no minimum.
080       *
081       * @return the minimum
082       * @see #getMaximumAccessibleValue()
083       */
084      Number getMinimumAccessibleValue();
085    
086      /**
087       * Gets the maximum value in the range of this object, or null if there is
088       * no maximum.
089       *
090       * @return the maximum
091       * @see #getMinimumAccessibleValue()
092       */
093      Number getMaximumAccessibleValue();
094    } // interface AccessibleValue