/*

 * Copyright 2000-2007 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.awt;

import java.awt.ScrollPane;

import java.awt.Insets;

import java.awt.Adjustable;

import java.awt.event.MouseWheelEvent;

/*

 * ScrollPaneWheelScroller is a helper class for implmenenting mouse wheel

 * scrolling on a java.awt.ScrollPane.  It contains only static methods.

 * No objects of this class may be instantiated, thus it is declared abstract.

 */

public abstract class ScrollPaneWheelScroller {

    private ScrollPaneWheelScroller() {}

    /*

     * Called from ScrollPane.processMouseWheelEvent()

     */

    public static void handleWheelScrolling(ScrollPane sp, MouseWheelEvent e) {

        }

        int increment = 0;

        if (sp != null && e.getScrollAmount() != 0) {

            Adjustable adj = getAdjustableToScroll(sp);

            if (adj != null) {

                increment = getIncrementFromAdjustable(adj, e);

                }

                scrollAdjustable(adj, increment);

            }

        }

    }

    /*

     * Given a ScrollPane, determine which Scrollbar should be scrolled by the

     * mouse wheel, if any.

     */

    public static Adjustable getAdjustableToScroll(ScrollPane sp) {

        int policy = sp.getScrollbarDisplayPolicy();

        // if policy is display always or never, use vert

        if (policy == ScrollPane.SCROLLBARS_ALWAYS ||

            policy == ScrollPane.SCROLLBARS_NEVER) {

            }

            return sp.getVAdjustable();

        }

        else {

            Insets ins = sp.getInsets();

            int vertScrollWidth = sp.getVScrollbarWidth();

                 ", t = " + ins.top + ", b = " + ins.bottom);

            }

            // Check if scrollbar is showing by examining insets of the

            // ScrollPane

            if (ins.right >= vertScrollWidth) {

                }

                return sp.getVAdjustable();

            }

            else {

                int horizScrollHeight = sp.getHScrollbarHeight();

                if (ins.bottom >= horizScrollHeight) {

                    }

                    return sp.getHAdjustable();

                }

                else {

                    }

                    return null;

                }

            }

        }

    }

    /*

     * Given the info in a MouseWheelEvent and an Adjustable to scroll, return

     * the amount by which the Adjustable should be adjusted.  This value may

     * be positive or negative.

     */

    public static int getIncrementFromAdjustable(Adjustable adj,

                                                 MouseWheelEvent e) {

            if (adj == null) {

            }

        }

        int increment = 0;

        if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {

            increment = e.getUnitsToScroll() * adj.getUnitIncrement();

        }

        else if (e.getScrollType() == MouseWheelEvent.WHEEL_BLOCK_SCROLL) {

            increment = adj.getBlockIncrement() * e.getWheelRotation();

        }

        return increment;

    }

    /*

     * Scroll the given Adjustable by the given amount.  Checks the Adjustable's

     * bounds and sets the new value to the Adjustable.

     */

    public static void scrollAdjustable(Adjustable adj, int amount) {

            if (adj == null) {

            }

            if (amount == 0) {

            }

        }

        int current = adj.getValue();

        int upperLimit = adj.getMaximum() - adj.getVisibleAmount();

        }

        if (amount > 0 && current < upperLimit) { // still some room to scroll

                                                  // down

            if (current + amount < upperLimit) {

                adj.setValue(current + amount);

                return;

            }

            else {

                adj.setValue(upperLimit);

                return;

            }

        }

        else if (amount < 0 && current > adj.getMinimum()) { // still some room

                                                             // to scroll up

            if (current + amount > adj.getMinimum()) {

                adj.setValue(current + amount);

                return;

            }

            else {

                adj.setValue(adj.getMinimum());

                return;

            }

        }

    }

}