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/*
 * Copyright (c) 1997, 2013, 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
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 */

package javax.swing;

import java.io.Serializable;
import java.awt.Component;
import java.awt.Adjustable;
import java.awt.Dimension;
import java.awt.event.AdjustmentListener;
import java.awt.event.AdjustmentEvent;
import java.awt.Graphics;

import javax.swing.event.*;
import javax.swing.plaf.*;
import javax.accessibility.*;

import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;




An implementation of a scrollbar. The user positions the knob in the
scrollbar to determine the contents of the viewing area. The
program typically adjusts the display so that the end of the
scrollbar represents the end of the displayable contents, or 100%
of the contents. The start of the scrollbar is the beginning of the
displayable contents, or 0%. The position of the knob within
those bounds then translates to the corresponding percentage of
the displayable contents.


Typically, as the position of the knob in the scrollbar changes
a corresponding change is made to the position of the JViewport on
the underlying view, changing the contents of the JViewport.


Warning: Swing is not thread safe. For more
information see Swing's Threading
Policy.


Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeans™
has been added to the java.beans package. Please see XMLEncoder. 
Author:David Kloba
See Also:
@beaninfo
     attribute: isContainer false
   description: A component that helps determine the visible content range of an area.
/**
 * An implementation of a scrollbar. The user positions the knob in the
 * scrollbar to determine the contents of the viewing area. The
 * program typically adjusts the display so that the end of the
 * scrollbar represents the end of the displayable contents, or 100%
 * of the contents. The start of the scrollbar is the beginning of the
 * displayable contents, or 0%. The position of the knob within
 * those bounds then translates to the corresponding percentage of
 * the displayable contents.
 * <p>
 * Typically, as the position of the knob in the scrollbar changes
 * a corresponding change is made to the position of the JViewport on
 * the underlying view, changing the contents of the JViewport.
 * <p>
 * <strong>Warning:</strong> Swing is not thread safe. For more
 * information see <a
 * href="package-summary.html#threading">Swing's Threading
 * Policy</a>.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @see JScrollPane
 * @beaninfo
 *      attribute: isContainer false
 *    description: A component that helps determine the visible content range of an area.
 *
 * @author David Kloba
 */
public class JScrollBar extends JComponent implements Adjustable, Accessible
{
    
See Also:
/**
     * @see #getUIClassID
     * @see #readObject
     */
    private static final String uiClassID = "ScrollBarUI";

    
All changes from the model are treated as though the user moved
the scrollbar knob.

/**
     * All changes from the model are treated as though the user moved
     * the scrollbar knob.
     */
    private ChangeListener fwdAdjustmentEvents = new ModelListener();


    
The model that represents the scrollbar's minimum, maximum, extent
(aka "visibleAmount") and current value.

See Also:
  • setModel
/**
     * The model that represents the scrollbar's minimum, maximum, extent
     * (aka "visibleAmount") and current value.
     * @see #setModel
     */
    protected BoundedRangeModel model;


    
See Also:
  • setOrientation
/**
     * @see #setOrientation
     */
    protected int orientation;


    
See Also:
  • setUnitIncrement
/**
     * @see #setUnitIncrement
     */
    protected int unitIncrement;


    
See Also:
  • setBlockIncrement
/**
     * @see #setBlockIncrement
     */
    protected int blockIncrement;


    private void checkOrientation(int orientation) {
        switch (orientation) {
        case VERTICAL:
        case HORIZONTAL:
            break;
        default:
            throw new IllegalArgumentException("orientation must be one of: VERTICAL, HORIZONTAL");
        }
    }


    
Creates a scrollbar with the specified orientation,
value, extent, minimum, and maximum.
The "extent" is the size of the viewable area. It is also known
as the "visible amount".


Note: Use setBlockIncrement to set the block
increment to a size slightly smaller than the view's extent.
That way, when the user jumps the knob to an adjacent position,
one or two lines of the original contents remain in view.

Throws:
  • IllegalArgumentException – if orientation is not one of VERTICAL, HORIZONTAL
See Also:
/**
     * Creates a scrollbar with the specified orientation,
     * value, extent, minimum, and maximum.
     * The "extent" is the size of the viewable area. It is also known
     * as the "visible amount".
     * <p>
     * Note: Use <code>setBlockIncrement</code> to set the block
     * increment to a size slightly smaller than the view's extent.
     * That way, when the user jumps the knob to an adjacent position,
     * one or two lines of the original contents remain in view.
     *
     * @exception IllegalArgumentException if orientation is not one of VERTICAL, HORIZONTAL
     *
     * @see #setOrientation
     * @see #setValue
     * @see #setVisibleAmount
     * @see #setMinimum
     * @see #setMaximum
     */
    public JScrollBar(int orientation, int value, int extent, int min, int max)
    {
        checkOrientation(orientation);
        this.unitIncrement = 1;
        this.blockIncrement = (extent == 0) ? 1 : extent;
        this.orientation = orientation;
        this.model = new DefaultBoundedRangeModel(value, extent, min, max);
        this.model.addChangeListener(fwdAdjustmentEvents);
        setRequestFocusEnabled(false);
        updateUI();
    }


    
Creates a scrollbar with the specified orientation
and the following initial values:

minimum = 0
maximum = 100
value = 0
extent = 10



/**
     * Creates a scrollbar with the specified orientation
     * and the following initial values:
     * <pre>
     * minimum = 0
     * maximum = 100
     * value = 0
     * extent = 10
     * </pre>
     */
    public JScrollBar(int orientation) {
        this(orientation, 0, 10, 0, 100);
    }


    
Creates a vertical scrollbar with the following initial values:

minimum = 0
maximum = 100
value = 0
extent = 10



/**
     * Creates a vertical scrollbar with the following initial values:
     * <pre>
     * minimum = 0
     * maximum = 100
     * value = 0
     * extent = 10
     * </pre>
     */
    public JScrollBar() {
        this(VERTICAL);
    }


    
Sets the L&F object that renders this component. 
Params:
  • ui –  the ScrollBarUI L&F object
See Also:
Since:1.4
@beaninfo
       bound: true
      hidden: true
   attribute: visualUpdate true
 description: The UI object that implements the Component's LookAndFeel
/**
     * Sets the {@literal L&F} object that renders this component.
     *
     * @param ui  the <code>ScrollBarUI</code> {@literal L&F} object
     * @see UIDefaults#getUI
     * @since 1.4
     * @beaninfo
     *        bound: true
     *       hidden: true
     *    attribute: visualUpdate true
     *  description: The UI object that implements the Component's LookAndFeel
     */
    public void setUI(ScrollBarUI ui) {
        super.setUI(ui);
    }


    
Returns the delegate that implements the look and feel for
this component.

See Also:
  • setUI.setUI
/**
     * Returns the delegate that implements the look and feel for
     * this component.
     *
     * @see JComponent#setUI
     */
    public ScrollBarUI getUI() {
        return (ScrollBarUI)ui;
    }


    
Overrides JComponent.updateUI.

See Also:
  • updateUI.updateUI
/**
     * Overrides <code>JComponent.updateUI</code>.
     * @see JComponent#updateUI
     */
    public void updateUI() {
        setUI((ScrollBarUI)UIManager.getUI(this));
    }


    
Returns the name of the LookAndFeel class for this component.

See Also:
Returns:"ScrollBarUI"
/**
     * Returns the name of the LookAndFeel class for this component.
     *
     * @return "ScrollBarUI"
     * @see JComponent#getUIClassID
     * @see UIDefaults#getUI
     */
    public String getUIClassID() {
        return uiClassID;
    }



    
Returns the component's orientation (horizontal or vertical).

See Also:
Returns:VERTICAL or HORIZONTAL
/**
     * Returns the component's orientation (horizontal or vertical).
     *
     * @return VERTICAL or HORIZONTAL
     * @see #setOrientation
     * @see java.awt.Adjustable#getOrientation
     */
    public int getOrientation() {
        return orientation;
    }


    
Set the scrollbar's orientation to either VERTICAL or
HORIZONTAL.

Throws:
  • IllegalArgumentException – if orientation is not one of VERTICAL, HORIZONTAL
See Also:
@beaninfo
   preferred: true
       bound: true
   attribute: visualUpdate true
 description: The scrollbar's orientation.
        enum: VERTICAL JScrollBar.VERTICAL
              HORIZONTAL JScrollBar.HORIZONTAL
/**
     * Set the scrollbar's orientation to either VERTICAL or
     * HORIZONTAL.
     *
     * @exception IllegalArgumentException if orientation is not one of VERTICAL, HORIZONTAL
     * @see #getOrientation
     * @beaninfo
     *    preferred: true
     *        bound: true
     *    attribute: visualUpdate true
     *  description: The scrollbar's orientation.
     *         enum: VERTICAL JScrollBar.VERTICAL
     *               HORIZONTAL JScrollBar.HORIZONTAL
     */
    public void setOrientation(int orientation)
    {
        checkOrientation(orientation);
        int oldValue = this.orientation;
        this.orientation = orientation;
        firePropertyChange("orientation", oldValue, orientation);

        if ((oldValue != orientation) && (accessibleContext != null)) {
            accessibleContext.firePropertyChange(
                    AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                    ((oldValue == VERTICAL)
                     ? AccessibleState.VERTICAL : AccessibleState.HORIZONTAL),
                    ((orientation == VERTICAL)
                     ? AccessibleState.VERTICAL : AccessibleState.HORIZONTAL));
        }
        if (orientation != oldValue) {
            revalidate();
        }
    }


    
Returns data model that handles the scrollbar's four
fundamental properties: minimum, maximum, value, extent.

See Also:
  • setModel
/**
     * Returns data model that handles the scrollbar's four
     * fundamental properties: minimum, maximum, value, extent.
     *
     * @see #setModel
     */
    public BoundedRangeModel getModel() {
        return model;
    }


    
Sets the model that handles the scrollbar's four
fundamental properties: minimum, maximum, value, extent.

See Also:
  • getModel
@beaninfo
      bound: true
      expert: true
description: The scrollbar's BoundedRangeModel.
/**
     * Sets the model that handles the scrollbar's four
     * fundamental properties: minimum, maximum, value, extent.
     *
     * @see #getModel
     * @beaninfo
     *       bound: true
     *       expert: true
     * description: The scrollbar's BoundedRangeModel.
     */
    public void setModel(BoundedRangeModel newModel) {
        Integer oldValue = null;
        BoundedRangeModel oldModel = model;
        if (model != null) {
            model.removeChangeListener(fwdAdjustmentEvents);
            oldValue = Integer.valueOf(model.getValue());
        }
        model = newModel;
        if (model != null) {
            model.addChangeListener(fwdAdjustmentEvents);
        }

        firePropertyChange("model", oldModel, model);

        if (accessibleContext != null) {
            accessibleContext.firePropertyChange(
                    AccessibleContext.ACCESSIBLE_VALUE_PROPERTY,
                    oldValue, new Integer(model.getValue()));
        }
    }


    
Returns the amount to change the scrollbar's value by,
given a unit up/down request.  A ScrollBarUI implementation
typically calls this method when the user clicks on a scrollbar
up/down arrow and uses the result to update the scrollbar's
value.   Subclasses my override this method to compute
a value, e.g. the change required to scroll up or down one
(variable height) line text or one row in a table.


The JScrollPane component creates scrollbars (by default)
that override this method and delegate to the viewports
Scrollable view, if it has one.  The Scrollable interface
provides a more specialized version of this method.


Some look and feels implement custom scrolling behavior
and ignore this property.

Params:
  • direction – is -1 or 1 for up/down respectively
See Also:
Returns:the value of the unitIncrement property
/**
     * Returns the amount to change the scrollbar's value by,
     * given a unit up/down request.  A ScrollBarUI implementation
     * typically calls this method when the user clicks on a scrollbar
     * up/down arrow and uses the result to update the scrollbar's
     * value.   Subclasses my override this method to compute
     * a value, e.g. the change required to scroll up or down one
     * (variable height) line text or one row in a table.
     * <p>
     * The JScrollPane component creates scrollbars (by default)
     * that override this method and delegate to the viewports
     * Scrollable view, if it has one.  The Scrollable interface
     * provides a more specialized version of this method.
     * <p>
     * Some look and feels implement custom scrolling behavior
     * and ignore this property.
     *
     * @param direction is -1 or 1 for up/down respectively
     * @return the value of the unitIncrement property
     * @see #setUnitIncrement
     * @see #setValue
     * @see Scrollable#getScrollableUnitIncrement
     */
    public int getUnitIncrement(int direction) {
        return unitIncrement;
    }


    
Sets the unitIncrement property.


Note, that if the argument is equal to the value of Integer.MIN_VALUE,
the most look and feels will not provide the scrolling to the right/down.


Some look and feels implement custom scrolling behavior
and ignore this property.

See Also:
  • getUnitIncrement
@beaninfo
  preferred: true
      bound: true
description: The scrollbar's unit increment.
/**
     * Sets the unitIncrement property.
     * <p>
     * Note, that if the argument is equal to the value of Integer.MIN_VALUE,
     * the most look and feels will not provide the scrolling to the right/down.
     * <p>
     * Some look and feels implement custom scrolling behavior
     * and ignore this property.
     *
     * @see #getUnitIncrement
     * @beaninfo
     *   preferred: true
     *       bound: true
     * description: The scrollbar's unit increment.
     */
    public void setUnitIncrement(int unitIncrement) {
        int oldValue = this.unitIncrement;
        this.unitIncrement = unitIncrement;
        firePropertyChange("unitIncrement", oldValue, unitIncrement);
    }


    
Returns the amount to change the scrollbar's value by,
given a block (usually "page") up/down request.  A ScrollBarUI
implementation typically calls this method when the user clicks
above or below the scrollbar "knob" to change the value
up or down by large amount.  Subclasses my override this
method to compute a value, e.g. the change required to scroll
up or down one paragraph in a text document.


The JScrollPane component creates scrollbars (by default)
that override this method and delegate to the viewports
Scrollable view, if it has one.  The Scrollable interface
provides a more specialized version of this method.


Some look and feels implement custom scrolling behavior
and ignore this property.

Params:
  • direction – is -1 or 1 for up/down respectively
See Also:
Returns:the value of the blockIncrement property
/**
     * Returns the amount to change the scrollbar's value by,
     * given a block (usually "page") up/down request.  A ScrollBarUI
     * implementation typically calls this method when the user clicks
     * above or below the scrollbar "knob" to change the value
     * up or down by large amount.  Subclasses my override this
     * method to compute a value, e.g. the change required to scroll
     * up or down one paragraph in a text document.
     * <p>
     * The JScrollPane component creates scrollbars (by default)
     * that override this method and delegate to the viewports
     * Scrollable view, if it has one.  The Scrollable interface
     * provides a more specialized version of this method.
     * <p>
     * Some look and feels implement custom scrolling behavior
     * and ignore this property.
     *
     * @param direction is -1 or 1 for up/down respectively
     * @return the value of the blockIncrement property
     * @see #setBlockIncrement
     * @see #setValue
     * @see Scrollable#getScrollableBlockIncrement
     */
    public int getBlockIncrement(int direction) {
        return blockIncrement;
    }


    
Sets the blockIncrement property.


Note, that if the argument is equal to the value of Integer.MIN_VALUE,
the most look and feels will not provide the scrolling to the right/down.


Some look and feels implement custom scrolling behavior
and ignore this property.

See Also:
  • getBlockIncrement()
@beaninfo
  preferred: true
      bound: true
description: The scrollbar's block increment.
/**
     * Sets the blockIncrement property.
     * <p>
     * Note, that if the argument is equal to the value of Integer.MIN_VALUE,
     * the most look and feels will not provide the scrolling to the right/down.
     * <p>
     * Some look and feels implement custom scrolling behavior
     * and ignore this property.
     *
     * @see #getBlockIncrement()
     * @beaninfo
     *   preferred: true
     *       bound: true
     * description: The scrollbar's block increment.
     */
    public void setBlockIncrement(int blockIncrement) {
        int oldValue = this.blockIncrement;
        this.blockIncrement = blockIncrement;
        firePropertyChange("blockIncrement", oldValue, blockIncrement);
    }


    
For backwards compatibility with java.awt.Scrollbar.

See Also:
/**
     * For backwards compatibility with java.awt.Scrollbar.
     * @see Adjustable#getUnitIncrement
     * @see #getUnitIncrement(int)
     */
    public int getUnitIncrement() {
        return unitIncrement;
    }


    
For backwards compatibility with java.awt.Scrollbar.

See Also:
/**
     * For backwards compatibility with java.awt.Scrollbar.
     * @see Adjustable#getBlockIncrement
     * @see #getBlockIncrement(int)
     */
    public int getBlockIncrement() {
        return blockIncrement;
    }


    
Returns the scrollbar's value.

See Also:
Returns:the model's value property
/**
     * Returns the scrollbar's value.
     * @return the model's value property
     * @see #setValue
     */
    public int getValue() {
        return getModel().getValue();
    }


    
Sets the scrollbar's value.  This method just forwards the value
to the model.

See Also:
@beaninfo
  preferred: true
description: The scrollbar's current value.
/**
     * Sets the scrollbar's value.  This method just forwards the value
     * to the model.
     *
     * @see #getValue
     * @see BoundedRangeModel#setValue
     * @beaninfo
     *   preferred: true
     * description: The scrollbar's current value.
     */
    public void setValue(int value) {
        BoundedRangeModel m = getModel();
        int oldValue = m.getValue();
        m.setValue(value);

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


    
Returns the scrollbar's extent, aka its "visibleAmount".  In many
scrollbar look and feel implementations the size of the
scrollbar "knob" or "thumb" is proportional to the extent.

See Also:
Returns:the value of the model's extent property
/**
     * Returns the scrollbar's extent, aka its "visibleAmount".  In many
     * scrollbar look and feel implementations the size of the
     * scrollbar "knob" or "thumb" is proportional to the extent.
     *
     * @return the value of the model's extent property
     * @see #setVisibleAmount
     */
    public int getVisibleAmount() {
        return getModel().getExtent();
    }


    
Set the model's extent property.

See Also:
@beaninfo
  preferred: true
description: The amount of the view that is currently visible.
/**
     * Set the model's extent property.
     *
     * @see #getVisibleAmount
     * @see BoundedRangeModel#setExtent
     * @beaninfo
     *   preferred: true
     * description: The amount of the view that is currently visible.
     */
    public void setVisibleAmount(int extent) {
        getModel().setExtent(extent);
    }


    
Returns the minimum value supported by the scrollbar
(usually zero).

See Also:
Returns:the value of the model's minimum property
/**
     * Returns the minimum value supported by the scrollbar
     * (usually zero).
     *
     * @return the value of the model's minimum property
     * @see #setMinimum
     */
    public int getMinimum() {
        return getModel().getMinimum();
    }


    
Sets the model's minimum property.

See Also:
@beaninfo
  preferred: true
description: The scrollbar's minimum value.
/**
     * Sets the model's minimum property.
     *
     * @see #getMinimum
     * @see BoundedRangeModel#setMinimum
     * @beaninfo
     *   preferred: true
     * description: The scrollbar's minimum value.
     */
    public void setMinimum(int minimum) {
        getModel().setMinimum(minimum);
    }


    
The maximum value of the scrollbar is maximum - extent.

See Also:
Returns:the value of the model's maximum property
/**
     * The maximum value of the scrollbar is maximum - extent.
     *
     * @return the value of the model's maximum property
     * @see #setMaximum
     */
    public int getMaximum() {
        return getModel().getMaximum();
    }


    
Sets the model's maximum property.  Note that the scrollbar's value
can only be set to maximum - extent.

See Also:
@beaninfo
  preferred: true
description: The scrollbar's maximum value.
/**
     * Sets the model's maximum property.  Note that the scrollbar's value
     * can only be set to maximum - extent.
     *
     * @see #getMaximum
     * @see BoundedRangeModel#setMaximum
     * @beaninfo
     *   preferred: true
     * description: The scrollbar's maximum value.
     */
    public void setMaximum(int maximum) {
        getModel().setMaximum(maximum);
    }


    
True if the scrollbar knob is being dragged.

See Also:
Returns:the value of the model's valueIsAdjusting property
/**
     * True if the scrollbar knob is being dragged.
     *
     * @return the value of the model's valueIsAdjusting property
     * @see #setValueIsAdjusting
     */
    public boolean getValueIsAdjusting() {
        return getModel().getValueIsAdjusting();
    }


    
Sets the model's valueIsAdjusting property.  Scrollbar look and
feel implementations should set this property to true when
a knob drag begins, and to false when the drag ends.  The
scrollbar model will not generate ChangeEvents while
valueIsAdjusting is true.

See Also:
@beaninfo
     expert: true
description: True if the scrollbar thumb is being dragged.
/**
     * Sets the model's valueIsAdjusting property.  Scrollbar look and
     * feel implementations should set this property to true when
     * a knob drag begins, and to false when the drag ends.  The
     * scrollbar model will not generate ChangeEvents while
     * valueIsAdjusting is true.
     *
     * @see #getValueIsAdjusting
     * @see BoundedRangeModel#setValueIsAdjusting
     * @beaninfo
     *      expert: true
     * description: True if the scrollbar thumb is being dragged.
     */
    public void setValueIsAdjusting(boolean b) {
        BoundedRangeModel m = getModel();
        boolean oldValue = m.getValueIsAdjusting();
        m.setValueIsAdjusting(b);

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


    
Sets the four BoundedRangeModel properties after forcing
the arguments to obey the usual constraints:

minimum ≤ value ≤ value+extent ≤ maximum



See Also:
/**
     * Sets the four BoundedRangeModel properties after forcing
     * the arguments to obey the usual constraints:
     * <pre>
     * minimum &le; value &le; value+extent &le; maximum
     * </pre>
     *
     *
     * @see BoundedRangeModel#setRangeProperties
     * @see #setValue
     * @see #setVisibleAmount
     * @see #setMinimum
     * @see #setMaximum
     */
    public void setValues(int newValue, int newExtent, int newMin, int newMax)
    {
        BoundedRangeModel m = getModel();
        int oldValue = m.getValue();
        m.setRangeProperties(newValue, newExtent, newMin, newMax, m.getValueIsAdjusting());

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


    
Adds an AdjustmentListener.  Adjustment listeners are notified
each time the scrollbar's model changes.  Adjustment events are
provided for backwards compatibility with java.awt.Scrollbar.


Note that the AdjustmentEvents type property will always have a
placeholder value of AdjustmentEvent.TRACK because all changes
to a BoundedRangeModels value are considered equivalent.  To change
the value of a BoundedRangeModel one just sets its value property,
i.e. model.setValue(123).  No information about the origin of the
change, e.g. it's a block decrement, is provided.  We don't try
fabricate the origin of the change here.

Params:
  • l – the AdjustmentLister to add
See Also:
/**
     * Adds an AdjustmentListener.  Adjustment listeners are notified
     * each time the scrollbar's model changes.  Adjustment events are
     * provided for backwards compatibility with java.awt.Scrollbar.
     * <p>
     * Note that the AdjustmentEvents type property will always have a
     * placeholder value of AdjustmentEvent.TRACK because all changes
     * to a BoundedRangeModels value are considered equivalent.  To change
     * the value of a BoundedRangeModel one just sets its value property,
     * i.e. model.setValue(123).  No information about the origin of the
     * change, e.g. it's a block decrement, is provided.  We don't try
     * fabricate the origin of the change here.
     *
     * @param l the AdjustmentLister to add
     * @see #removeAdjustmentListener
     * @see BoundedRangeModel#addChangeListener
     */
    public void addAdjustmentListener(AdjustmentListener l)   {
        listenerList.add(AdjustmentListener.class, l);
    }


    
Removes an AdjustmentEvent listener.

Params:
  • l – the AdjustmentLister to remove
See Also:
/**
     * Removes an AdjustmentEvent listener.
     *
     * @param l the AdjustmentLister to remove
     * @see #addAdjustmentListener
     */
    public void removeAdjustmentListener(AdjustmentListener l)  {
        listenerList.remove(AdjustmentListener.class, l);
    }


    
Returns an array of all the AdjustmentListeners added
to this JScrollBar with addAdjustmentListener().

Returns:all of the AdjustmentListeners added or an empty
        array if no listeners have been added
Since:1.4
/**
     * Returns an array of all the <code>AdjustmentListener</code>s added
     * to this JScrollBar with addAdjustmentListener().
     *
     * @return all of the <code>AdjustmentListener</code>s added or an empty
     *         array if no listeners have been added
     * @since 1.4
     */
    public AdjustmentListener[] getAdjustmentListeners() {
        return listenerList.getListeners(AdjustmentListener.class);
    }


    
Notify listeners that the scrollbar's model has changed.

See Also:
/**
     * Notify listeners that the scrollbar's model has changed.
     *
     * @see #addAdjustmentListener
     * @see EventListenerList
     */
    protected void fireAdjustmentValueChanged(int id, int type, int value) {
        fireAdjustmentValueChanged(id, type, value, getValueIsAdjusting());
    }

    
Notify listeners that the scrollbar's model has changed.

See Also:
/**
     * Notify listeners that the scrollbar's model has changed.
     *
     * @see #addAdjustmentListener
     * @see EventListenerList
     */
    private void fireAdjustmentValueChanged(int id, int type, int value,
                                            boolean isAdjusting) {
        Object[] listeners = listenerList.getListenerList();
        AdjustmentEvent e = null;
        for (int i = listeners.length - 2; i >= 0; i -= 2) {
            if (listeners[i]==AdjustmentListener.class) {
                if (e == null) {
                    e = new AdjustmentEvent(this, id, type, value, isAdjusting);
                }
                ((AdjustmentListener)listeners[i+1]).adjustmentValueChanged(e);
            }
        }
    }


    
This class listens to ChangeEvents on the model and forwards
AdjustmentEvents for the sake of backwards compatibility.
Unfortunately there's no way to determine the proper
type of the AdjustmentEvent as all updates to the model's
value are considered equivalent.

/**
     * This class listens to ChangeEvents on the model and forwards
     * AdjustmentEvents for the sake of backwards compatibility.
     * Unfortunately there's no way to determine the proper
     * type of the AdjustmentEvent as all updates to the model's
     * value are considered equivalent.
     */
    private class ModelListener implements ChangeListener, Serializable {
        public void stateChanged(ChangeEvent e)   {
            Object obj = e.getSource();
            if (obj instanceof BoundedRangeModel) {
                int id = AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED;
                int type = AdjustmentEvent.TRACK;
                BoundedRangeModel model = (BoundedRangeModel)obj;
                int value = model.getValue();
                boolean isAdjusting = model.getValueIsAdjusting();
                fireAdjustmentValueChanged(id, type, value, isAdjusting);
            }
        }
    }

    // PENDING(hmuller) - the next three methods should be removed

    
The scrollbar is flexible along it's scrolling axis and
rigid along the other axis.

/**
     * The scrollbar is flexible along it's scrolling axis and
     * rigid along the other axis.
     */
    public Dimension getMinimumSize() {
        Dimension pref = getPreferredSize();
        if (orientation == VERTICAL) {
            return new Dimension(pref.width, 5);
        } else {
            return new Dimension(5, pref.height);
        }
    }

    
The scrollbar is flexible along it's scrolling axis and
rigid along the other axis.

/**
     * The scrollbar is flexible along it's scrolling axis and
     * rigid along the other axis.
     */
    public Dimension getMaximumSize() {
        Dimension pref = getPreferredSize();
        if (getOrientation() == VERTICAL) {
            return new Dimension(pref.width, Short.MAX_VALUE);
        } else {
            return new Dimension(Short.MAX_VALUE, pref.height);
        }
    }

    
Enables the component so that the knob position can be changed.
When the disabled, the knob position cannot be changed.

Params:
  • x – a boolean value, where true enables the component and
         false disables it
/**
     * Enables the component so that the knob position can be changed.
     * When the disabled, the knob position cannot be changed.
     *
     * @param x a boolean value, where true enables the component and
     *          false disables it
     */
    public void setEnabled(boolean x)  {
        super.setEnabled(x);
        Component[] children = getComponents();
        for (Component child : children) {
            child.setEnabled(x);
        }
    }

    
See readObject() and writeObject() in JComponent for more
information about serialization in Swing.

/**
     * See readObject() and writeObject() in JComponent for more
     * information about serialization in Swing.
     */
    private void writeObject(ObjectOutputStream s) throws IOException {
        s.defaultWriteObject();
        if (getUIClassID().equals(uiClassID)) {
            byte count = JComponent.getWriteObjCounter(this);
            JComponent.setWriteObjCounter(this, --count);
            if (count == 0 && ui != null) {
                ui.installUI(this);
            }
        }
    }


    
Returns a string representation of this JScrollBar. 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 null.

Returns: a string representation of this JScrollBar.
/**
     * Returns a string representation of this JScrollBar. 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  a string representation of this JScrollBar.
     */
    protected String paramString() {
        String orientationString = (orientation == HORIZONTAL ?
                                    "HORIZONTAL" : "VERTICAL");

        return super.paramString() +
        ",blockIncrement=" + blockIncrement +
        ",orientation=" + orientationString +
        ",unitIncrement=" + unitIncrement;
    }

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

    
Gets the AccessibleContext associated with this JScrollBar.
For JScrollBar, the AccessibleContext takes the form of an
AccessibleJScrollBar.
A new AccessibleJScrollBar instance is created if necessary.

Returns:an AccessibleJScrollBar that serves as the
        AccessibleContext of this JScrollBar
/**
     * Gets the AccessibleContext associated with this JScrollBar.
     * For JScrollBar, the AccessibleContext takes the form of an
     * AccessibleJScrollBar.
     * A new AccessibleJScrollBar instance is created if necessary.
     *
     * @return an AccessibleJScrollBar that serves as the
     *         AccessibleContext of this JScrollBar
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleJScrollBar();
        }
        return accessibleContext;
    }

    
This class implements accessibility support for the
JScrollBar class.  It provides an implementation of the
Java Accessibility API appropriate to scroll bar user-interface
elements.


Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeans™
has been added to the java.beans package. Please see XMLEncoder. 
/**
     * This class implements accessibility support for the
     * <code>JScrollBar</code> class.  It provides an implementation of the
     * Java Accessibility API appropriate to scroll bar user-interface
     * elements.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans&trade;
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    protected class AccessibleJScrollBar extends AccessibleJComponent
        implements AccessibleValue {

        
Get the state set of this object.

See Also:
Returns:an instance of AccessibleState containing the current state
of the object
/**
         * Get the state set of this object.
         *
         * @return an instance of AccessibleState 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.

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

        
Get the AccessibleValue associated with this object.  In the
implementation of the Java Accessibility API for this class,
return this object, which is responsible for implementing the
AccessibleValue interface on behalf of itself.

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

        
Get the accessible value of this object.

Returns:The current value of this object.
/**
         * 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.

Returns:True if the value was set.
/**
         * Set the value of this object as a Number.
         *
         * @return True if the value was set.
         */
        public boolean setCurrentAccessibleValue(Number n) {
            // TIGER - 4422535
            if (n == null) {
                return false;
            }
            setValue(n.intValue());
            return true;
        }

        
Get the minimum accessible value of this object.

Returns:The minimum value of this object.
/**
         * 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.

Returns:The maximum value of this object.
/**
         * Get the maximum accessible value of this object.
         *
         * @return The maximum value of this object.
         */
        public Number getMaximumAccessibleValue() {
            // TIGER - 4422362
            return new Integer(model.getMaximum() - model.getExtent());
        }

    } // AccessibleJScrollBar
}