001    /* Scrollable.java --
002       Copyright (C) 2002, 2004 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    package javax.swing;
039    
040    import java.awt.Dimension;
041    import java.awt.Rectangle;
042    
043    /**
044     * Defines the method that a component should implement to behave nicely
045     * in {@link JScrollPane}s. Note that this is not required for a component
046     * to be used in a <code>JScrollPane</code>, but can highly improve the
047     * user experience when scrolling the component.
048     */
049    public interface Scrollable
050    {
051      Dimension getPreferredScrollableViewportSize();
052    
053      /**
054       * Return the preferred scrolling amount (in pixels) for the given
055       * scrolling direction and orientation when scrolling in small amounts
056       * like table lines.
057       *
058       * @param visibleRect the currently visible part of the component.
059       * @param orientation the scrolling orientation
060       * @param direction the scrolling direction (negative - up, positive -down).
061       * The values greater than one means that more mouse wheel or similar
062       * events were generated, and hence it is better to scroll the longer
063       * distance.
064       *
065       * @return the preferred scrolling distance, negative if up or left.
066       */
067      int getScrollableUnitIncrement(Rectangle visibleRect, int orientation,
068                                     int direction);
069    
070      /**
071       * Return the preferred scrolling amount (in pixels) for the given
072       * scrolling direction and orientation when scrolling in large amounts
073       * (pages).
074       *
075       * @param visibleRect the currently visible part of the component.
076       * @param orientation the scrolling orientation
077       * @param direction the scrolling direction (negative - up, positive -down).
078       * The values greater than one means that more mouse wheel or similar
079       * events were generated, and hence it is better to scroll the longer
080       * distance.
081       *
082       * @return the preferred scrolling distance, negative if up or left.
083       */
084      int getScrollableBlockIncrement(Rectangle visibleRect, int orientation,
085                                      int direction);
086    
087      /**
088       * Return true if the width of the scrollable is always equal to the
089       * view, where it is displayed, width (for instance, the text area with
090       * the word wrap). In such case, the horizontal scrolling should not be
091       * performed.
092       *
093       * @return true is no horizontal scrolling is assumed, faster otherwise.
094       */
095      boolean getScrollableTracksViewportWidth();
096    
097      /**
098       * Return true if the height of the scrollable is always equal to the view,
099       * where it is displayed, height.In such case, the vertical scrolling should
100       * not be performed.
101       *
102       * @return true is no horizontal scrolling is assumed, faster otherwise.
103       */
104      boolean getScrollableTracksViewportHeight();
105    
106    }