001/* Scrollable.java -- 
002   Copyright (C) 2002, 2004 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package javax.swing;
039
040import java.awt.Dimension;
041import 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 */
049public 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}