/*
 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 */
package java.awt;

import java.awt.peer.ScrollbarPeer;
import java.awt.event.*;
import java.util.EventListener;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import javax.accessibility.*;


/**
 * The <code>Scrollbar</code> class embodies a scroll bar, a
 * familiar user-interface object. A scroll bar provides a
 * convenient means for allowing a user to select from a
 * range of values. The following three vertical
 * scroll bars could be used as slider controls to pick
 * the red, green, and blue components of a color:
 * <p>
 * <img src="doc-files/Scrollbar-1.gif" alt="Image shows 3 vertical sliders, side-by-side."
 * style="float:center; margin: 7px 10px;">
 * <p>
 * Each scroll bar in this example could be created with
 * code similar to the following:
 *
 * <hr><blockquote><pre>
 * redSlider=new Scrollbar(Scrollbar.VERTICAL, 0, 1, 0, 255);
 * add(redSlider);
 * </pre></blockquote><hr>
 * <p>
 * Alternatively, a scroll bar can represent a range of values. For
 * example, if a scroll bar is used for scrolling through text, the
 * width of the "bubble" (also called the "thumb" or "scroll box")
 * can be used to represent the amount of text that is visible.
 * Here is an example of a scroll bar that represents a range:
 * <p>
 * <img src="doc-files/Scrollbar-2.gif"
 * alt="Image shows horizontal slider with starting range of 0 and ending range of 300. The slider thumb is labeled 60."
 * style="float:center; margin: 7px 10px;">
 * <p>
 * The value range represented by the bubble in this example
 * is the <em>visible amount</em>. The horizontal scroll bar
 * in this example could be created with code like the following:
 *
 * <hr><blockquote><pre>
 * ranger = new Scrollbar(Scrollbar.HORIZONTAL, 0, 60, 0, 300);
 * add(ranger);
 * </pre></blockquote><hr>
 * <p>
 * Note that the actual maximum value of the scroll bar is the
 * <code>maximum</code> minus the <code>visible amount</code>.
 * In the previous example, because the <code>maximum</code> is
 * 300 and the <code>visible amount</code> is 60, the actual maximum
 * value is 240. The range of the scrollbar track is 0 - 300.
 * The left side of the bubble indicates the value of the
 * scroll bar.
 * <p>
 * Normally, the user changes the value of the scroll bar by
 * making a gesture with the mouse. For example, the user can
 * drag the scroll bar's bubble up and down, or click in the
 * scroll bar's unit increment or block increment areas. Keyboard
 * gestures can also be mapped to the scroll bar. By convention,
 * the <b>Page&nbsp;Up</b> and <b>Page&nbsp;Down</b>
 * keys are equivalent to clicking in the scroll bar's block
 * increment and block decrement areas.
 * <p>
 * When the user changes the value of the scroll bar, the scroll bar
 * receives an instance of <code>AdjustmentEvent</code>.
 * The scroll bar processes this event, passing it along to
 * any registered listeners.
 * <p>
 * Any object that wishes to be notified of changes to the
 * scroll bar's value should implement
 * <code>AdjustmentListener</code>, an interface defined in
 * the package <code>java.awt.event</code>.
 * Listeners can be added and removed dynamically by calling
 * the methods <code>addAdjustmentListener</code> and
 * <code>removeAdjustmentListener</code>.
 * <p>
 * The <code>AdjustmentEvent</code> class defines five types
 * of adjustment event, listed here:
 *
 * <ul>
 * <li><code>AdjustmentEvent.TRACK</code> is sent out when the
 * user drags the scroll bar's bubble.
 * <li><code>AdjustmentEvent.UNIT_INCREMENT</code> is sent out
 * when the user clicks in the left arrow of a horizontal scroll
 * bar, or the top arrow of a vertical scroll bar, or makes the
 * equivalent gesture from the keyboard.
 * <li><code>AdjustmentEvent.UNIT_DECREMENT</code> is sent out
 * when the user clicks in the right arrow of a horizontal scroll
 * bar, or the bottom arrow of a vertical scroll bar, or makes the
 * equivalent gesture from the keyboard.
 * <li><code>AdjustmentEvent.BLOCK_INCREMENT</code> is sent out
 * when the user clicks in the track, to the left of the bubble
 * on a horizontal scroll bar, or above the bubble on a vertical
 * scroll bar. By convention, the <b>Page&nbsp;Up</b>
 * key is equivalent, if the user is using a keyboard that
 * defines a <b>Page&nbsp;Up</b> key.
 * <li><code>AdjustmentEvent.BLOCK_DECREMENT</code> is sent out
 * when the user clicks in the track, to the right of the bubble
 * on a horizontal scroll bar, or below the bubble on a vertical
 * scroll bar. By convention, the <b>Page&nbsp;Down</b>
 * key is equivalent, if the user is using a keyboard that
 * defines a <b>Page&nbsp;Down</b> key.
 * </ul>
 * <p>
 * The JDK&nbsp;1.0 event system is supported for backwards
 * compatibility, but its use with newer versions of the platform is
 * discouraged. The five types of adjustment events introduced
 * with JDK&nbsp;1.1 correspond to the five event types
 * that are associated with scroll bars in previous platform versions.
 * The following list gives the adjustment event type,
 * and the corresponding JDK&nbsp;1.0 event type it replaces.
 *
 * <ul>
 * <li><code>AdjustmentEvent.TRACK</code> replaces
 * <code>Event.SCROLL_ABSOLUTE</code>
 * <li><code>AdjustmentEvent.UNIT_INCREMENT</code> replaces
 * <code>Event.SCROLL_LINE_UP</code>
 * <li><code>AdjustmentEvent.UNIT_DECREMENT</code> replaces
 * <code>Event.SCROLL_LINE_DOWN</code>
 * <li><code>AdjustmentEvent.BLOCK_INCREMENT</code> replaces
 * <code>Event.SCROLL_PAGE_UP</code>
 * <li><code>AdjustmentEvent.BLOCK_DECREMENT</code> replaces
 * <code>Event.SCROLL_PAGE_DOWN</code>
 * </ul>
 * <p>
 * <b>Note</b>: We recommend using a <code>Scrollbar</code>
 * for value selection only. If you want to implement
 * a scrollable component inside a container, we recommend you use
 * a {@link ScrollPane ScrollPane}. If you use a
 * <code>Scrollbar</code> for this purpose, you are likely to
 * encounter issues with painting, key handling, sizing and
 * positioning.
 *
 * @author Sami Shaio
 * @see java.awt.event.AdjustmentEvent
 * @see java.awt.event.AdjustmentListener
 * @since JDK1.0
 */
public class Scrollbar extends Component implements Adjustable, Accessible {

 /**
 * A constant that indicates a horizontal scroll bar.
 */
 public static final int HORIZONTAL = 0;

 /**
 * A constant that indicates a vertical scroll bar.
 */
 public static final int VERTICAL = 1;

 /**
 * The value of the <code>Scrollbar</code>.
 * This property must be greater than or equal to <code>minimum</code>
 * and less than or equal to
 * <code>maximum - visibleAmount</code>
 *
 * @serial
 * @see #getValue
 * @see #setValue
 */
 int value;

 /**
 * The maximum value of the <code>Scrollbar</code>.
 * This value must be greater than the <code>minimum</code>
 * value.<br>
 *
 * @serial
 * @see #getMaximum
 * @see #setMaximum
 */
 int maximum;

 /**
 * The minimum value of the <code>Scrollbar</code>.
 * This value must be less than the <code>maximum</code>
 * value.<br>
 *
 * @serial
 * @see #getMinimum
 * @see #setMinimum
 */
 int minimum;

 /**
 * The size of the <code>Scrollbar</code>'s bubble.
 * When a scroll bar is used to select a range of values,
 * the visibleAmount represents the size of this range.
 * Depending on platform, this may be visually indicated
 * by the size of the bubble.
 *
 * @serial
 * @see #getVisibleAmount
 * @see #setVisibleAmount
 */
 int visibleAmount;

 /**
 * The <code>Scrollbar</code>'s orientation--being either horizontal
 * or vertical.
 * This value should be specified when the scrollbar is created.<BR>
 * orientation can be either : <code>VERTICAL</code> or
 * <code>HORIZONTAL</code> only.
 *
 * @serial
 * @see #getOrientation
 * @see #setOrientation
 */
 int orientation;

 /**
 * The amount by which the scrollbar value will change when going
 * up or down by a line.
 * This value must be greater than zero.
 *
 * @serial
 * @see #getLineIncrement
 * @see #setLineIncrement
 */
 int lineIncrement = 1;

 /**
 * The amount by which the scrollbar value will change when going
 * up or down by a page.
 * This value must be greater than zero.
 *
 * @serial
 * @see #getPageIncrement
 * @see #setPageIncrement
 */
 int pageIncrement = 10;

 /**
 * The adjusting status of the <code>Scrollbar</code>.
 * True if the value is in the process of changing as a result of
 * actions being taken by the user.
 *
 * @see #getValueIsAdjusting
 * @see #setValueIsAdjusting
 * @since 1.4
 */
 transient boolean isAdjusting;

 transient AdjustmentListener adjustmentListener;

 private static final String base = "scrollbar";
 private static int nameCounter = 0;

 /*
 * JDK 1.1 serialVersionUID
 */
 private static final long serialVersionUID = 8451667562882310543L;

 /**
 * Initialize JNI field and method IDs.
 */
 private static native void initIDs();

 static {
 /* ensure that the necessary native libraries are loaded */
 Toolkit.loadLibraries();
 if (!GraphicsEnvironment.isHeadless()) {
 initIDs();
 }
 }

 /**
 * Constructs a new vertical scroll bar.
 * The default properties of the scroll bar are listed in
 * the following table:
 *
 * <table border=1 summary="Scrollbar default properties">
 * <tr>
 * <th>Property</th>
 * <th>Description</th>
 * <th>Default Value</th>
 * </tr>
 * <tr>
 * <td>orientation</td>
 * <td>indicates whether the scroll bar is vertical
 * <br>or horizontal</td>
 * <td><code>Scrollbar.VERTICAL</code></td>
 * </tr>
 * <tr>
 * <td>value</td>
 * <td>value which controls the location
 * <br>of the scroll bar's bubble</td>
 * <td>0</td>
 * </tr>
 * <tr>
 * <td>visible amount</td>
 * <td>visible amount of the scroll bar's range,
 * <br>typically represented by the size of the
 * <br>scroll bar's bubble</td>
 * <td>10</td>
 * </tr>
 * <tr>
 * <td>minimum</td>
 * <td>minimum value of the scroll bar</td>
 * <td>0</td>
 * </tr>
 * <tr>
 * <td>maximum</td>
 * <td>maximum value of the scroll bar</td>
 * <td>100</td>
 * </tr>
 * <tr>
 * <td>unit increment</td>
 * <td>amount the value changes when the
 * <br>Line Up or Line Down key is pressed,
 * <br>or when the end arrows of the scrollbar
 * <br>are clicked </td>
 * <td>1</td>
 * </tr>
 * <tr>
 * <td>block increment</td>
 * <td>amount the value changes when the
 * <br>Page Up or Page Down key is pressed,
 * <br>or when the scrollbar track is clicked
 * <br>on either side of the bubble </td>
 * <td>10</td>
 * </tr>
 * </table>
 *
 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
 * returns true.
 * @see java.awt.GraphicsEnvironment#isHeadless
 */
 public Scrollbar() throws HeadlessException {
 this(VERTICAL, 0, 10, 0, 100);
 }

 /**
 * Constructs a new scroll bar with the specified orientation.
 * <p>
 * The <code>orientation</code> argument must take one of the two
 * values <code>Scrollbar.HORIZONTAL</code>,
 * or <code>Scrollbar.VERTICAL</code>,
 * indicating a horizontal or vertical scroll bar, respectively.
 *
 * @param orientation indicates the orientation of the scroll bar
 * @exception IllegalArgumentException when an illegal value for
 * the <code>orientation</code> argument is supplied
 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
 * returns true.
 * @see java.awt.GraphicsEnvironment#isHeadless
 */
 public Scrollbar(int orientation) throws HeadlessException {
 this(orientation, 0, 10, 0, 100);
 }

 /**
 * Constructs a new scroll bar with the specified orientation,
 * initial value, visible amount, and minimum and maximum values.
 * <p>
 * The <code>orientation</code> argument must take one of the two
 * values <code>Scrollbar.HORIZONTAL</code>,
 * or <code>Scrollbar.VERTICAL</code>,
 * indicating a horizontal or vertical scroll bar, respectively.
 * <p>
 * The parameters supplied to this constructor are subject to the
 * constraints described in {@link #setValues(int, int, int, int)}.
 *
 * @param orientation indicates the orientation of the scroll bar.
 * @param value the initial value of the scroll bar
 * @param visible the visible amount of the scroll bar, typically
 * represented by the size of the bubble
 * @param minimum the minimum value of the scroll bar
 * @param maximum the maximum value of the scroll bar
 * @exception IllegalArgumentException when an illegal value for
 * the <code>orientation</code> argument is supplied
 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
 * returns true.
 * @see #setValues
 * @see java.awt.GraphicsEnvironment#isHeadless
 */
 public Scrollbar(int orientation, int value, int visible, int minimum,
 int maximum) throws HeadlessException {
 GraphicsEnvironment.checkHeadless();
 switch (orientation) {
 case HORIZONTAL:
 case VERTICAL:
 this.orientation = orientation;
 break;
 default:
 throw new IllegalArgumentException("illegal scrollbar orientation");
 }
 setValues(value, visible, minimum, maximum);
 }

 /**
 * Constructs a name for this component. Called by <code>getName</code>
 * when the name is <code>null</code>.
 */
 String constructComponentName() {
 synchronized (Scrollbar.class) {
 return base + nameCounter++;
 }
 }

 /**
 * Creates the <code>Scrollbar</code>'s peer. The peer allows you to modify
 * the appearance of the <code>Scrollbar</code> without changing any of its
 * functionality.
 */
 public void addNotify() {
 synchronized (getTreeLock()) {
 if (peer == null)
 peer = getToolkit().createScrollbar(this);
 super.addNotify();
 }
 }

 /**
 * Returns the orientation of this scroll bar.
 *
 * @return the orientation of this scroll bar, either
 * <code>Scrollbar.HORIZONTAL</code> or
 * <code>Scrollbar.VERTICAL</code>
 * @see java.awt.Scrollbar#setOrientation
 */
 public int getOrientation() {
 return orientation;
 }

 /**
 * Sets the orientation for this scroll bar.
 *
 * @param orientation the orientation of this scroll bar, either
 * <code>Scrollbar.HORIZONTAL</code> or
 * <code>Scrollbar.VERTICAL</code>
 * @see java.awt.Scrollbar#getOrientation
 * @exception IllegalArgumentException if the value supplied
 * for <code>orientation</code> is not a
 * legal value
 * @since JDK1.1
 */
 public void setOrientation(int orientation) {
 synchronized (getTreeLock()) {
 if (orientation == this.orientation) {
 return;
 }
 switch (orientation) {
 case HORIZONTAL:
 case VERTICAL:
 this.orientation = orientation;
 break;
 default:
 throw new IllegalArgumentException("illegal scrollbar orientation");
 }
 /* Create a new peer with the specified orientation. */
 if (peer != null) {
 removeNotify();
 addNotify();
 invalidate();
 }
 }
 if (accessibleContext != null) {
 accessibleContext.firePropertyChange(
 AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
 ((orientation == VERTICAL)
 ? AccessibleState.HORIZONTAL : AccessibleState.VERTICAL),
 ((orientation == VERTICAL)
 ? AccessibleState.VERTICAL : AccessibleState.HORIZONTAL));
 }
 }

 /**
 * Gets the current value of this scroll bar.
 *
 * @return the current value of this scroll bar
 * @see java.awt.Scrollbar#getMinimum
 * @see java.awt.Scrollbar#getMaximum
 */
 public int getValue() {
 return value;
 }

 /**
 * Sets the value of this scroll bar to the specified value.
 * <p>
 * If the value supplied is less than the current <code>minimum</code>
 * or greater than the current <code>maximum - visibleAmount</code>,
 * then either <code>minimum</code> or <code>maximum - visibleAmount</code>
 * is substituted, as appropriate.
 * <p>
 * Normally, a program should change a scroll bar's
 * value only by calling <code>setValues</code>.
 * The <code>setValues</code> method simultaneously
 * and synchronously sets the minimum, maximum, visible amount,
 * and value properties of a scroll bar, so that they are
 * mutually consistent.
 * <p>
 * Calling this method does not fire an
 * <code>AdjustmentEvent</code>.
 *
 * @param newValue the new value of the scroll bar
 * @see java.awt.Scrollbar#setValues
 * @see java.awt.Scrollbar#getValue
 * @see java.awt.Scrollbar#getMinimum
 * @see java.awt.Scrollbar#getMaximum
 */
 public void setValue(int newValue) {
 // Use setValues so that a consistent policy relating
 // minimum, maximum, visible amount, and value is enforced.
 setValues(newValue, visibleAmount, minimum, maximum);
 }

 /**
 * Gets the minimum value of this scroll bar.
 *
 * @return the minimum value of this scroll bar
 * @see java.awt.Scrollbar#getValue
 * @see java.awt.Scrollbar#getMaximum
 */
 public int getMinimum() {
 return minimum;
 }

 /**
 * Sets the minimum value of this scroll bar.
 * <p>
 * When <code>setMinimum</code> is called, the minimum value
 * is changed, and other values (including the maximum, the
 * visible amount, and the current scroll bar value)
 * are changed to be consistent with the new minimum.
 * <p>
 * Normally, a program should change a scroll bar's minimum
 * value only by calling <code>setValues</code>.
 * The <code>setValues</code> method simultaneously
 * and synchronously sets the minimum, maximum, visible amount,
 * and value properties of a scroll bar, so that they are
 * mutually consistent.
 * <p>
 * Note that setting the minimum value to <code>Integer.MAX_VALUE</code>
 * will result in the new minimum value being set to
 * <code>Integer.MAX_VALUE - 1</code>.
 *
 * @param newMinimum the new minimum value for this scroll bar
 * @see java.awt.Scrollbar#setValues
 * @see java.awt.Scrollbar#setMaximum
 * @since JDK1.1
 */
 public void setMinimum(int newMinimum) {
 // No checks are necessary in this method since minimum is
 // the first variable checked in the setValues function.

 // Use setValues so that a consistent policy relating
 // minimum, maximum, visible amount, and value is enforced.
 setValues(value, visibleAmount, newMinimum, maximum);
 }

 /**
 * Gets the maximum value of this scroll bar.
 *
 * @return the maximum value of this scroll bar
 * @see java.awt.Scrollbar#getValue
 * @see java.awt.Scrollbar#getMinimum
 */
 public int getMaximum() {
 return maximum;
 }

 /**
 * Sets the maximum value of this scroll bar.
 * <p>
 * When <code>setMaximum</code> is called, the maximum value
 * is changed, and other values (including the minimum, the
 * visible amount, and the current scroll bar value)
 * are changed to be consistent with the new maximum.
 * <p>
 * Normally, a program should change a scroll bar's maximum
 * value only by calling <code>setValues</code>.
 * The <code>setValues</code> method simultaneously
 * and synchronously sets the minimum, maximum, visible amount,
 * and value properties of a scroll bar, so that they are
 * mutually consistent.
 * <p>
 * Note that setting the maximum value to <code>Integer.MIN_VALUE</code>
 * will result in the new maximum value being set to
 * <code>Integer.MIN_VALUE + 1</code>.
 *
 * @param newMaximum the new maximum value
 * for this scroll bar
 * @see java.awt.Scrollbar#setValues
 * @see java.awt.Scrollbar#setMinimum
 * @since JDK1.1
 */
 public void setMaximum(int newMaximum) {
 // minimum is checked first in setValues, so we need to
 // enforce minimum and maximum checks here.
 if (newMaximum == Integer.MIN_VALUE) {
 newMaximum = Integer.MIN_VALUE + 1;
 }

 if (minimum >= newMaximum) {
 minimum = newMaximum - 1;
 }

 // Use setValues so that a consistent policy relating
 // minimum, maximum, visible amount, and value is enforced.
 setValues(value, visibleAmount, minimum, newMaximum);
 }

 /**
 * Gets the visible amount of this scroll bar.
 * <p>
 * When a scroll bar is used to select a range of values,
 * the visible amount is used to represent the range of values
 * that are currently visible. The size of the scroll bar's
 * bubble (also called a thumb or scroll box), usually gives a
 * visual representation of the relationship of the visible
 * amount to the range of the scroll bar.
 * Note that depending on platform, the value of the visible amount property
 * may not be visually indicated by the size of the bubble.
 * <p>
 * The scroll bar's bubble may not be displayed when it is not
 * moveable (e.g. when it takes up the entire length of the
 * scroll bar's track, or when the scroll bar is disabled).
 * Whether the bubble is displayed or not will not affect
 * the value returned by <code>getVisibleAmount</code>.
 *
 * @return the visible amount of this scroll bar
 * @see java.awt.Scrollbar#setVisibleAmount
 * @since JDK1.1
 */
 public int getVisibleAmount() {
 return getVisible();
 }

 /**
 * @deprecated As of JDK version 1.1,
 * replaced by <code>getVisibleAmount()</code>.
 */
 @Deprecated
 public int getVisible() {
 return visibleAmount;
 }

 /**
 * Sets the visible amount of this scroll bar.
 * <p>
 * When a scroll bar is used to select a range of values,
 * the visible amount is used to represent the range of values
 * that are currently visible. The size of the scroll bar's
 * bubble (also called a thumb or scroll box), usually gives a
 * visual representation of the relationship of the visible
 * amount to the range of the scroll bar.
 * Note that depending on platform, the value of the visible amount property
 * may not be visually indicated by the size of the bubble.
 * <p>
 * The scroll bar's bubble may not be displayed when it is not
 * moveable (e.g. when it takes up the entire length of the
 * scroll bar's track, or when the scroll bar is disabled).
 * Whether the bubble is displayed or not will not affect
 * the value returned by <code>getVisibleAmount</code>.
 * <p>
 * If the visible amount supplied is less than <code>one</code>
 * or greater than the current <code>maximum - minimum</code>,
 * then either <code>one</code> or <code>maximum - minimum</code>
 * is substituted, as appropriate.
 * <p>
 * Normally, a program should change a scroll bar's
 * value only by calling <code>setValues</code>.
 * The <code>setValues</code> method simultaneously
 * and synchronously sets the minimum, maximum, visible amount,
 * and value properties of a scroll bar, so that they are
 * mutually consistent.
 *
 * @param newAmount the new visible amount
 * @see java.awt.Scrollbar#getVisibleAmount
 * @see java.awt.Scrollbar#setValues
 * @since JDK1.1
 */
 public void setVisibleAmount(int newAmount) {
 // Use setValues so that a consistent policy relating
 // minimum, maximum, visible amount, and value is enforced.
 setValues(value, newAmount, minimum, maximum);
 }

 /**
 * Sets the unit increment for this scroll bar.
 * <p>
 * The unit increment is the value that is added or subtracted
 * when the user activates the unit increment area of the
 * scroll bar, generally through a mouse or keyboard gesture
 * that the scroll bar receives as an adjustment event.
 * The unit increment must be greater than zero.
 * Attepts to set the unit increment to a value lower than 1
 * will result in a value of 1 being set.
 * <p>
 * In some operating systems, this property
 * can be ignored by the underlying controls.
 *
 * @param v the amount by which to increment or decrement
 * the scroll bar's value
 * @see java.awt.Scrollbar#getUnitIncrement
 * @since JDK1.1
 */
 public void setUnitIncrement(int v) {
 setLineIncrement(v);
 }

 /**
 * @deprecated As of JDK version 1.1,
 * replaced by <code>setUnitIncrement(int)</code>.
 */
 @Deprecated
 public synchronized void setLineIncrement(int v) {
 int tmp = (v < 1) ? 1 : v;

 if (lineIncrement == tmp) {
 return;
 }
 lineIncrement = tmp;

 ScrollbarPeer peer = (ScrollbarPeer)this.peer;
 if (peer != null) {
 peer.setLineIncrement(lineIncrement);
 }
 }

 /**
 * Gets the unit increment for this scrollbar.
 * <p>
 * The unit increment is the value that is added or subtracted
 * when the user activates the unit increment area of the
 * scroll bar, generally through a mouse or keyboard gesture
 * that the scroll bar receives as an adjustment event.
 * The unit increment must be greater than zero.
 * <p>
 * In some operating systems, this property
 * can be ignored by the underlying controls.
 *
 * @return the unit increment of this scroll bar
 * @see java.awt.Scrollbar#setUnitIncrement
 * @since JDK1.1
 */
 public int getUnitIncrement() {
 return getLineIncrement();
 }

 /**
 * @deprecated As of JDK version 1.1,
 * replaced by <code>getUnitIncrement()</code>.
 */
 @Deprecated
 public int getLineIncrement() {
 return lineIncrement;
 }

 /**
 * Sets the block increment for this scroll bar.
 * <p>
 * The block increment is the value that is added or subtracted
 * when the user activates the block increment area of the
 * scroll bar, generally through a mouse or keyboard gesture
 * that the scroll bar receives as an adjustment event.
 * The block increment must be greater than zero.
 * Attepts to set the block increment to a value lower than 1
 * will result in a value of 1 being set.
 *
 * @param v the amount by which to increment or decrement
 * the scroll bar's value
 * @see java.awt.Scrollbar#getBlockIncrement
 * @since JDK1.1
 */
 public void setBlockIncrement(int v) {
 setPageIncrement(v);
 }

 /**
 * @deprecated As of JDK version 1.1,
 * replaced by <code>setBlockIncrement()</code>.
 */
 @Deprecated
 public synchronized void setPageIncrement(int v) {
 int tmp = (v < 1) ? 1 : v;

 if (pageIncrement == tmp) {
 return;
 }
 pageIncrement = tmp;

 ScrollbarPeer peer = (ScrollbarPeer)this.peer;
 if (peer != null) {
 peer.setPageIncrement(pageIncrement);
 }
 }

 /**
 * Gets the block increment of this scroll bar.
 * <p>
 * The block increment is the value that is added or subtracted
 * when the user activates the block increment area of the
 * scroll bar, generally through a mouse or keyboard gesture
 * that the scroll bar receives as an adjustment event.
 * The block increment must be greater than zero.
 *
 * @return the block increment of this scroll bar
 * @see java.awt.Scrollbar#setBlockIncrement
 * @since JDK1.1
 */
 public int getBlockIncrement() {
 return getPageIncrement();
 }

 /**
 * @deprecated As of JDK version 1.1,
 * replaced by <code>getBlockIncrement()</code>.
 */
 @Deprecated
 public int getPageIncrement() {
 return pageIncrement;
 }

 /**
 * Sets the values of four properties for this scroll bar:
 * <code>value</code>, <code>visibleAmount</code>,
 * <code>minimum</code>, and <code>maximum</code>.
 * If the values supplied for these properties are inconsistent
 * or incorrect, they will be changed to ensure consistency.
 * <p>
 * This method simultaneously and synchronously sets the values
 * of four scroll bar properties, assuring that the values of
 * these properties are mutually consistent. It enforces the
 * following constraints:
 * <code>maximum</code> must be greater than <code>minimum</code>,
 * <code>maximum - minimum</code> must not be greater
 * than <code>Integer.MAX_VALUE</code>,
 * <code>visibleAmount</code> must be greater than zero.
 * <code>visibleAmount</code> must not be greater than
 * <code>maximum - minimum</code>,
 * <code>value</code> must not be less than <code>minimum</code>,
 * and <code>value</code> must not be greater than
 * <code>maximum - visibleAmount</code>
 * <p>
 * Calling this method does not fire an
 * <code>AdjustmentEvent</code>.
 *
 * @param value is the position in the current window
 * @param visible is the visible amount of the scroll bar
 * @param minimum is the minimum value of the scroll bar
 * @param maximum is the maximum value of the scroll bar
 * @see #setMinimum
 * @see #setMaximum
 * @see #setVisibleAmount
 * @see #setValue
 */
 public void setValues(int value, int visible, int minimum, int maximum) {
 int oldValue;
 synchronized (this) {
 if (minimum == Integer.MAX_VALUE) {
 minimum = Integer.MAX_VALUE - 1;
 }
 if (maximum <= minimum) {
 maximum = minimum + 1;
 }

 long maxMinusMin = (long) maximum - (long) minimum;
 if (maxMinusMin > Integer.MAX_VALUE) {
 maxMinusMin = Integer.MAX_VALUE;
 maximum = minimum + (int) maxMinusMin;
 }
 if (visible > (int) maxMinusMin) {
 visible = (int) maxMinusMin;
 }
 if (visible < 1) {
 visible = 1;
 }

 if (value < minimum) {
 value = minimum;
 }
 if (value > maximum - visible) {
 value = maximum - visible;
 }

 oldValue = this.value;
 this.value = value;
 this.visibleAmount = visible;
 this.minimum = minimum;
 this.maximum = maximum;
 ScrollbarPeer peer = (ScrollbarPeer)this.peer;
 if (peer != null) {
 peer.setValues(value, visibleAmount, minimum, maximum);
 }
 }

 if ((oldValue != value) && (accessibleContext != null)) {
 accessibleContext.firePropertyChange(
 AccessibleContext.ACCESSIBLE_VALUE_PROPERTY,
 Integer.valueOf(oldValue),
 Integer.valueOf(value));
 }
 }

 /**
 * Returns true if the value is in the process of changing as a
 * result of actions being taken by the user.
 *
 * @return the value of the <code>valueIsAdjusting</code> property
 * @see #setValueIsAdjusting
 * @since 1.4
 */
 public boolean getValueIsAdjusting() {
 return isAdjusting;
 }

 /**
 * Sets the <code>valueIsAdjusting</code> property.
 *
 * @param b new adjustment-in-progress status
 * @see #getValueIsAdjusting
 * @since 1.4
 */
 public void setValueIsAdjusting(boolean b) {
 boolean oldValue;

 synchronized (this) {
 oldValue = isAdjusting;
 isAdjusting = b;
 }

 if ((oldValue != b) && (accessibleContext != null)) {
 accessibleContext.firePropertyChange(
 AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
 ((oldValue) ? AccessibleState.BUSY : null),
 ((b) ? AccessibleState.BUSY : null));
 }
 }



 /**
 * Adds the specified adjustment listener to receive instances of
 * <code>AdjustmentEvent</code> from this scroll bar.
 * If l is <code>null</code>, no exception is thrown and no
 * action is performed.
 * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
 * >AWT Threading Issues</a> for details on AWT's threading model.
 *
 * @param l the adjustment listener
 * @see #removeAdjustmentListener
 * @see #getAdjustmentListeners
 * @see java.awt.event.AdjustmentEvent
 * @see java.awt.event.AdjustmentListener
 * @since JDK1.1
 */
 public synchronized void addAdjustmentListener(AdjustmentListener l) {
 if (l == null) {
 return;
 }
 adjustmentListener = AWTEventMulticaster.add(adjustmentListener, l);
 newEventsOnly = true;
 }

 /**
 * Removes the specified adjustment listener so that it no longer
 * receives instances of <code>AdjustmentEvent</code> from this scroll bar.
 * If l is <code>null</code>, no exception is thrown and no action
 * is performed.
 * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
 * >AWT Threading Issues</a> for details on AWT's threading model.
 *
 * @param l the adjustment listener
 * @see #addAdjustmentListener
 * @see #getAdjustmentListeners
 * @see java.awt.event.AdjustmentEvent
 * @see java.awt.event.AdjustmentListener
 * @since JDK1.1
 */
 public synchronized void removeAdjustmentListener(AdjustmentListener l) {
 if (l == null) {
 return;
 }
 adjustmentListener = AWTEventMulticaster.remove(adjustmentListener, l);
 }

 /**
 * Returns an array of all the adjustment listeners
 * registered on this scrollbar.
 *
 * @return all of this scrollbar's <code>AdjustmentListener</code>s
 * or an empty array if no adjustment
 * listeners are currently registered
 * @see #addAdjustmentListener
 * @see #removeAdjustmentListener
 * @see java.awt.event.AdjustmentEvent
 * @see java.awt.event.AdjustmentListener
 * @since 1.4
 */
 public synchronized AdjustmentListener[] getAdjustmentListeners() {
 return getListeners(AdjustmentListener.class);
 }

 /**
 * Returns an array of all the objects currently registered
 * as <code><em>Foo</em>Listener</code>s
 * upon this <code>Scrollbar</code>.
 * <code><em>Foo</em>Listener</code>s are registered using the
 * <code>add<em>Foo</em>Listener</code> method.
 * <p>
 * You can specify the <code>listenerType</code> argument
 * with a class literal, such as
 * <code><em>Foo</em>Listener.class</code>.
 * For example, you can query a
 * <code>Scrollbar</code> <code>c</code>
 * for its mouse listeners with the following code:
 *
 * <pre>MouseListener[] mls = (MouseListener[])(c.getListeners(MouseListener.class));</pre>
 *
 * If no such listeners exist, this method returns an empty array.
 *
 * @param listenerType the type of listeners requested; this parameter
 * should specify an interface that descends from
 * <code>java.util.EventListener</code>
 * @return an array of all objects registered as
 * <code><em>Foo</em>Listener</code>s on this component,
 * or an empty array if no such listeners have been added
 * @exception ClassCastException if <code>listenerType</code>
 * doesn't specify a class or interface that implements
 * <code>java.util.EventListener</code>
 *
 * @since 1.3
 */
 public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
 EventListener l = null;
 if (listenerType == AdjustmentListener.class) {
 l = adjustmentListener;
 } else {
 return super.getListeners(listenerType);
 }
 return AWTEventMulticaster.getListeners(l, listenerType);
 }

 // REMIND: remove when filtering is done at lower level
 boolean eventEnabled(AWTEvent e) {
 if (e.id == AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED) {
 if ((eventMask & AWTEvent.ADJUSTMENT_EVENT_MASK) != 0 ||
 adjustmentListener != null) {
 return true;
 }
 return false;
 }
 return super.eventEnabled(e);
 }

 /**
 * Processes events on this scroll bar. If the event is an
 * instance of <code>AdjustmentEvent</code>, it invokes the
 * <code>processAdjustmentEvent</code> method.
 * Otherwise, it invokes its superclass's
 * <code>processEvent</code> method.
 * <p>Note that if the event parameter is <code>null</code>
 * the behavior is unspecified and may result in an
 * exception.
 *
 * @param e the event
 * @see java.awt.event.AdjustmentEvent
 * @see java.awt.Scrollbar#processAdjustmentEvent
 * @since JDK1.1
 */
 protected void processEvent(AWTEvent e) {
 if (e instanceof AdjustmentEvent) {
 processAdjustmentEvent((AdjustmentEvent)e);
 return;
 }
 super.processEvent(e);
 }

 /**
 * Processes adjustment events occurring on this
 * scrollbar by dispatching them to any registered
 * <code>AdjustmentListener</code> objects.
 * <p>
 * This method is not called unless adjustment events are
 * enabled for this component. Adjustment events are enabled
 * when one of the following occurs:
 * <ul>
 * <li>An <code>AdjustmentListener</code> object is registered
 * via <code>addAdjustmentListener</code>.
 * <li>Adjustment events are enabled via <code>enableEvents</code>.
 * </ul>
 * <p>Note that if the event parameter is <code>null</code>
 * the behavior is unspecified and may result in an
 * exception.
 *
 * @param e the adjustment event
 * @see java.awt.event.AdjustmentEvent
 * @see java.awt.event.AdjustmentListener
 * @see java.awt.Scrollbar#addAdjustmentListener
 * @see java.awt.Component#enableEvents
 * @since JDK1.1
 */
 protected void processAdjustmentEvent(AdjustmentEvent e) {
 AdjustmentListener listener = adjustmentListener;
 if (listener != null) {
 listener.adjustmentValueChanged(e);
 }
 }

 /**
 * Returns a string representing the state of this <code>Scrollbar</code>.
 * This method is intended to be used only for debugging purposes, and the
 * content and format of the returned string may vary between
 * implementations. The returned string may be empty but may not be
 * <code>null</code>.
 *
 * @return the parameter string of this scroll bar
 */
 protected String paramString() {
 return super.paramString() +
 ",val=" + value +
 ",vis=" + visibleAmount +
 ",min=" + minimum +
 ",max=" + maximum +
 ((orientation == VERTICAL) ? ",vert" : ",horz") +
 ",isAdjusting=" + isAdjusting;
 }


 /* Serialization support.
 */

 /**
 * The scroll bar's serialized Data Version.
 *
 * @serial
 */
 private int scrollbarSerializedDataVersion = 1;

 /**
 * Writes default serializable fields to stream. Writes
 * a list of serializable <code>AdjustmentListeners</code>
 * as optional data. The non-serializable listeners are
 * detected and no attempt is made to serialize them.
 *
 * @param s the <code>ObjectOutputStream</code> to write
 * @serialData <code>null</code> terminated sequence of 0
 * or more pairs; the pair consists of a <code>String</code>
 * and an <code>Object</code>; the <code>String</code> indicates
 * the type of object and is one of the following:
 * <code>adjustmentListenerK</code> indicating an
 * <code>AdjustmentListener</code> object
 *
 * @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
 * @see java.awt.Component#adjustmentListenerK
 * @see #readObject(ObjectInputStream)
 */
 private void writeObject(ObjectOutputStream s)
 throws IOException
 {
 s.defaultWriteObject();

 AWTEventMulticaster.save(s, adjustmentListenerK, adjustmentListener);
 s.writeObject(null);
 }

 /**
 * Reads the <code>ObjectInputStream</code> and if
 * it isn't <code>null</code> adds a listener to
 * receive adjustment events fired by the
 * <code>Scrollbar</code>.
 * Unrecognized keys or values will be ignored.
 *
 * @param s the <code>ObjectInputStream</code> to read
 * @exception HeadlessException if
 * <code>GraphicsEnvironment.isHeadless</code> returns
 * <code>true</code>
 * @see java.awt.GraphicsEnvironment#isHeadless
 * @see #writeObject(ObjectOutputStream)
 */
 private void readObject(ObjectInputStream s)
 throws ClassNotFoundException, IOException, HeadlessException
 {
 GraphicsEnvironment.checkHeadless();
 s.defaultReadObject();

 Object keyOrNull;
 while(null != (keyOrNull = s.readObject())) {
 String key = ((String)keyOrNull).intern();

 if (adjustmentListenerK == key)
 addAdjustmentListener((AdjustmentListener)(s.readObject()));

 else // skip value for unrecognized key
 s.readObject();
 }
 }


/////////////////
// Accessibility support
////////////////

 /**
 * Gets the <code>AccessibleContext</code> associated with this
 * <code>Scrollbar</code>. For scrollbars, the
 * <code>AccessibleContext</code> takes the form of an
 * <code>AccessibleAWTScrollBar</code>. A new
 * <code>AccessibleAWTScrollBar</code> instance is created if necessary.
 *
 * @return an <code>AccessibleAWTScrollBar</code> that serves as the
 * <code>AccessibleContext</code> of this <code>ScrollBar</code>
 * @since 1.3
 */
 public AccessibleContext getAccessibleContext() {
 if (accessibleContext == null) {
 accessibleContext = new AccessibleAWTScrollBar();
 }
 return accessibleContext;
 }

 /**
 * This class implements accessibility support for the
 * <code>Scrollbar</code> class. It provides an implementation of
 * the Java Accessibility API appropriate to scrollbar
 * user-interface elements.
 * @since 1.3
 */
 protected class AccessibleAWTScrollBar extends AccessibleAWTComponent
 implements AccessibleValue
 {
 /*
 * JDK 1.3 serialVersionUID
 */
 private static final long serialVersionUID = -344337268523697807L;

 /**
 * Get the state set of this object.
 *
 * @return an instance of <code>AccessibleState</code>
 * containing the current state of the object
 * @see AccessibleState
 */
 public AccessibleStateSet getAccessibleStateSet() {
 AccessibleStateSet states = super.getAccessibleStateSet();
 if (getValueIsAdjusting()) {
 states.add(AccessibleState.BUSY);
 }
 if (getOrientation() == VERTICAL) {
 states.add(AccessibleState.VERTICAL);
 } else {
 states.add(AccessibleState.HORIZONTAL);
 }
 return states;
 }

 /**
 * Get the role of this object.
 *
 * @return an instance of <code>AccessibleRole</code>
 * describing the role of the object
 */
 public AccessibleRole getAccessibleRole() {
 return AccessibleRole.SCROLL_BAR;
 }

 /**
 * Get the <code>AccessibleValue</code> associated with this
 * object. In the implementation of the Java Accessibility
 * API for this class, return this object, which is
 * responsible for implementing the
 * <code>AccessibleValue</code> interface on behalf of itself.
 *
 * @return this object
 */
 public AccessibleValue getAccessibleValue() {
 return this;
 }

 /**
 * Get the accessible value of this object.
 *
 * @return The current value of this object.
 */
 public Number getCurrentAccessibleValue() {
 return Integer.valueOf(getValue());
 }

 /**
 * Set the value of this object as a Number.
 *
 * @return True if the value was set.
 */
 public boolean setCurrentAccessibleValue(Number n) {
 if (n instanceof Integer) {
 setValue(n.intValue());
 return true;
 } else {
 return false;
 }
 }

 /**
 * Get the minimum accessible value of this object.
 *
 * @return The minimum value of this object.
 */
 public Number getMinimumAccessibleValue() {
 return Integer.valueOf(getMinimum());
 }

 /**
 * Get the maximum accessible value of this object.
 *
 * @return The maximum value of this object.
 */
 public Number getMaximumAccessibleValue() {
 return Integer.valueOf(getMaximum());
 }

 } // AccessibleAWTScrollBar

}