/* * Copyright (c) 1997, 2003, 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.swing; import java.awt.Dimension;import java.awt.Rectangle;  /** * An interface that provides information to a scrolling container * like JScrollPane.  A complex component that's likely to be used * as a viewing a JScrollPane viewport (or other scrolling container) * should implement this interface. * * @see JViewport * @see JScrollPane * @see JScrollBar * @author Hans Muller */public interface Scrollable{    /**     * Returns the preferred size of the viewport for a view component.     * For example, the preferred size of a <code>JList</code> component     * is the size required to accommodate all of the cells in its list.     * However, the value of <code>preferredScrollableViewportSize</code>     * is the size required for <code>JList.getVisibleRowCount</code> rows.     * A component without any properties that would affect the viewport     * size should just return <code>getPreferredSize</code> here.     *     * @return the preferredSize of a <code>JViewport</code> whose view     *    is this <code>Scrollable</code>     * @see JViewport#getPreferredSize     */    Dimension getPreferredScrollableViewportSize();      /**     * Components that display logical rows or columns should compute     * the scroll increment that will completely expose one new row     * or column, depending on the value of orientation.  Ideally,     * components should handle a partially exposed row or column by     * returning the distance required to completely expose the item.     * <p>     * Scrolling containers, like JScrollPane, will use this method     * each time the user requests a unit scroll.     *     * @param visibleRect The view area visible within the viewport     * @param orientation Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.     * @param direction Less than zero to scroll up/left, greater than zero for down/right.     * @return The "unit" increment for scrolling in the specified direction.     *         This value should always be positive.     * @see JScrollBar#setUnitIncrement     */    int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction);      /**     * Components that display logical rows or columns should compute     * the scroll increment that will completely expose one block     * of rows or columns, depending on the value of orientation.     * <p>     * Scrolling containers, like JScrollPane, will use this method     * each time the user requests a block scroll.     *     * @param visibleRect The view area visible within the viewport     * @param orientation Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.     * @param direction Less than zero to scroll up/left, greater than zero for down/right.     * @return The "block" increment for scrolling in the specified direction.     *         This value should always be positive.     * @see JScrollBar#setBlockIncrement     */    int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction);      /**     * Return true if a viewport should always force the width of this     * <code>Scrollable</code> to match the width of the viewport.     * For example a normal     * text view that supported line wrapping would return true here, since it     * would be undesirable for wrapped lines to disappear beyond the right     * edge of the viewport.  Note that returning true for a Scrollable     * whose ancestor is a JScrollPane effectively disables horizontal     * scrolling.     * <p>     * Scrolling containers, like JViewport, will use this method each     * time they are validated.     *     * @return True if a viewport should force the Scrollables width to match its own.     */    boolean getScrollableTracksViewportWidth();     /**     * Return true if a viewport should always force the height of this     * Scrollable to match the height of the viewport.  For example a     * columnar text view that flowed text in left to right columns     * could effectively disable vertical scrolling by returning     * true here.     * <p>     * Scrolling containers, like JViewport, will use this method each     * time they are validated.     *     * @return True if a viewport should force the Scrollables height to match its own.     */    boolean getScrollableTracksViewportHeight();}