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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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,

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 *

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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();

}