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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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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();
}