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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package java.awt.event;

import java.awt.Component;

import java.lang.annotation.Native;


An event which indicates that the mouse wheel was rotated in a component.


A wheel mouse is a mouse which has a wheel in place of the middle button.
This wheel can be rotated towards or away from the user.  Mouse wheels are
most often used for scrolling, though other uses are possible.


A MouseWheelEvent object is passed to every MouseWheelListener
object which registered to receive the "interesting" mouse events using the
component's addMouseWheelListener method.  Each such listener
object gets a MouseEvent containing the mouse event.


Due to the mouse wheel's special relationship to scrolling Components,
MouseWheelEvents are delivered somewhat differently than other MouseEvents.
This is because while other MouseEvents usually affect a change on
the Component directly under the mouse
cursor (for instance, when clicking a button), MouseWheelEvents often have
an effect away from the mouse cursor (moving the wheel while
over a Component inside a ScrollPane should scroll one of the
Scrollbars on the ScrollPane).


MouseWheelEvents start delivery from the Component underneath the
mouse cursor.  If MouseWheelEvents are not enabled on the
Component, the event is delivered to the first ancestor
Container with MouseWheelEvents enabled.  This will usually be
a ScrollPane with wheel scrolling enabled.  The source
Component and x,y coordinates will be relative to the event's
final destination (the ScrollPane).  This allows a complex
GUI to be installed without modification into a ScrollPane, and
for all MouseWheelEvents to be delivered to the ScrollPane for
scrolling.


Some AWT Components are implemented using native widgets which
display their own scrollbars and handle their own scrolling.
The particular Components for which this is true will vary from
platform to platform.  When the mouse wheel is
moved over one of these Components, the event is delivered straight to
the native widget, and not propagated to ancestors.


Platforms offer customization of the amount of scrolling that
should take place when the mouse wheel is moved.  The two most
common settings are to scroll a certain number of "units"
(commonly lines of text in a text-based component) or an entire "block"
(similar to page-up/page-down).  The MouseWheelEvent offers
methods for conforming to the underlying platform settings.  These
platform settings can be changed at any time by the user.  MouseWheelEvents
reflect the most recent settings.


The MouseWheelEvent class includes methods for getting the number of "clicks" by which the mouse wheel is rotated. The getWheelRotation method returns the integer number of "clicks" corresponding to the number of notches by which the wheel was rotated. In addition to this method, the MouseWheelEvent class provides the getPreciseWheelRotation method which returns a double number of "clicks" in case a partial rotation occurred. The getPreciseWheelRotation method is useful if a mouse supports a high-resolution wheel, such as a freely rotating wheel with no notches. Applications can benefit by using this method to process mouse wheel events more precisely, and thus, making visual perception smoother. 
Author:Brent Christian
See Also:
Since:1.4
/**
 * An event which indicates that the mouse wheel was rotated in a component.
 * <P>
 * A wheel mouse is a mouse which has a wheel in place of the middle button.
 * This wheel can be rotated towards or away from the user.  Mouse wheels are
 * most often used for scrolling, though other uses are possible.
 * <P>
 * A MouseWheelEvent object is passed to every <code>MouseWheelListener</code>
 * object which registered to receive the "interesting" mouse events using the
 * component's <code>addMouseWheelListener</code> method.  Each such listener
 * object gets a <code>MouseEvent</code> containing the mouse event.
 * <P>
 * Due to the mouse wheel's special relationship to scrolling Components,
 * MouseWheelEvents are delivered somewhat differently than other MouseEvents.
 * This is because while other MouseEvents usually affect a change on
 * the Component directly under the mouse
 * cursor (for instance, when clicking a button), MouseWheelEvents often have
 * an effect away from the mouse cursor (moving the wheel while
 * over a Component inside a ScrollPane should scroll one of the
 * Scrollbars on the ScrollPane).
 * <P>
 * MouseWheelEvents start delivery from the Component underneath the
 * mouse cursor.  If MouseWheelEvents are not enabled on the
 * Component, the event is delivered to the first ancestor
 * Container with MouseWheelEvents enabled.  This will usually be
 * a ScrollPane with wheel scrolling enabled.  The source
 * Component and x,y coordinates will be relative to the event's
 * final destination (the ScrollPane).  This allows a complex
 * GUI to be installed without modification into a ScrollPane, and
 * for all MouseWheelEvents to be delivered to the ScrollPane for
 * scrolling.
 * <P>
 * Some AWT Components are implemented using native widgets which
 * display their own scrollbars and handle their own scrolling.
 * The particular Components for which this is true will vary from
 * platform to platform.  When the mouse wheel is
 * moved over one of these Components, the event is delivered straight to
 * the native widget, and not propagated to ancestors.
 * <P>
 * Platforms offer customization of the amount of scrolling that
 * should take place when the mouse wheel is moved.  The two most
 * common settings are to scroll a certain number of "units"
 * (commonly lines of text in a text-based component) or an entire "block"
 * (similar to page-up/page-down).  The MouseWheelEvent offers
 * methods for conforming to the underlying platform settings.  These
 * platform settings can be changed at any time by the user.  MouseWheelEvents
 * reflect the most recent settings.
 * <P>
 * The <code>MouseWheelEvent</code> class includes methods for
 * getting the number of "clicks" by which the mouse wheel is rotated.
 * The {@link #getWheelRotation} method returns the integer number
 * of "clicks" corresponding to the number of notches by which the wheel was
 * rotated. In addition to this method, the <code>MouseWheelEvent</code>
 * class provides the {@link #getPreciseWheelRotation} method which returns
 * a double number of "clicks" in case a partial rotation occurred.
 * The {@link #getPreciseWheelRotation} method is useful if a mouse supports
 * a high-resolution wheel, such as a freely rotating wheel with no
 * notches. Applications can benefit by using this method to process
 * mouse wheel events more precisely, and thus, making visual perception
 * smoother.
 *
 * @author Brent Christian
 * @see MouseWheelListener
 * @see java.awt.ScrollPane
 * @see java.awt.ScrollPane#setWheelScrollingEnabled(boolean)
 * @see javax.swing.JScrollPane
 * @see javax.swing.JScrollPane#setWheelScrollingEnabled(boolean)
 * @since 1.4
 */

public class MouseWheelEvent extends MouseEvent {

    
Constant representing scrolling by "units" (like scrolling with the
arrow keys)

See Also:
  • getScrollType
/**
     * Constant representing scrolling by "units" (like scrolling with the
     * arrow keys)
     *
     * @see #getScrollType
     */
    @Native public static final int WHEEL_UNIT_SCROLL = 0;

    
Constant representing scrolling by a "block" (like scrolling
with page-up, page-down keys)

See Also:
  • getScrollType
/**
     * Constant representing scrolling by a "block" (like scrolling
     * with page-up, page-down keys)
     *
     * @see #getScrollType
     */
    @Native public static final int WHEEL_BLOCK_SCROLL = 1;

    
Indicates what sort of scrolling should take place in response to this
event, based on platform settings.  Legal values are:

    

  •  WHEEL_UNIT_SCROLL

  •  WHEEL_BLOCK_SCROLL



See Also:
  • getScrollType
/**
     * Indicates what sort of scrolling should take place in response to this
     * event, based on platform settings.  Legal values are:
     * <ul>
     * <li> WHEEL_UNIT_SCROLL
     * <li> WHEEL_BLOCK_SCROLL
     * </ul>
     *
     * @see #getScrollType
     */
    int scrollType;

    
Only valid for scrollType WHEEL_UNIT_SCROLL.
Indicates number of units that should be scrolled per
click of mouse wheel rotation, based on platform settings.

See Also:
/**
     * Only valid for scrollType WHEEL_UNIT_SCROLL.
     * Indicates number of units that should be scrolled per
     * click of mouse wheel rotation, based on platform settings.
     *
     * @see #getScrollAmount
     * @see #getScrollType
     */
    int scrollAmount;

    
Indicates how far the mouse wheel was rotated.

See Also:
  • getWheelRotation
/**
     * Indicates how far the mouse wheel was rotated.
     *
     * @see #getWheelRotation
     */
    int wheelRotation;

    
Indicates how far the mouse wheel was rotated.

See Also:
  • getPreciseWheelRotation
/**
     * Indicates how far the mouse wheel was rotated.
     *
     * @see #getPreciseWheelRotation
     */
    double preciseWheelRotation;

    /*
     * serialVersionUID
     */

    private static final long serialVersionUID = 6459879390515399677L;

    
Constructs a MouseWheelEvent object with the
specified source component, type, modifiers, coordinates,
scroll type, scroll amount, and wheel rotation.

Absolute coordinates xAbs and yAbs are set to source's location on screen plus
relative coordinates x and y. xAbs and yAbs are set to zero if the source is not showing.

Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.

Params:
  • source –         the Component that originated
                      the event
  • id –             the integer that identifies the event
  • when –           a long that gives the time the event occurred
  • modifiers –      the modifier keys down during event
                      (shift, ctrl, alt, meta)
  • x –              the horizontal x coordinate for the mouse location
  • y –              the vertical y coordinate for the mouse location
  • clickCount –     the number of mouse clicks associated with event
  • popupTrigger –   a boolean, true if this event is a trigger for a
                      popup-menu
  • scrollType –     the type of scrolling which should take place in
                      response to this event;  valid values are
                      WHEEL_UNIT_SCROLL and
                      WHEEL_BLOCK_SCROLL
  • scrollAmount –  for scrollType WHEEL_UNIT_SCROLL,
                      the number of units to be scrolled
  • wheelRotation –  the integer number of "clicks" by which the mouse
                      wheel was rotated
Throws:
See Also:
/**
     * Constructs a <code>MouseWheelEvent</code> object with the
     * specified source component, type, modifiers, coordinates,
     * scroll type, scroll amount, and wheel rotation.
     * <p>Absolute coordinates xAbs and yAbs are set to source's location on screen plus
     * relative coordinates x and y. xAbs and yAbs are set to zero if the source is not showing.
     * <p>Note that passing in an invalid <code>id</code> results in
     * unspecified behavior. This method throws an
     * <code>IllegalArgumentException</code> if <code>source</code>
     * is <code>null</code>.
     *
     * @param source         the <code>Component</code> that originated
     *                       the event
     * @param id             the integer that identifies the event
     * @param when           a long that gives the time the event occurred
     * @param modifiers      the modifier keys down during event
     *                       (shift, ctrl, alt, meta)
     * @param x              the horizontal x coordinate for the mouse location
     * @param y              the vertical y coordinate for the mouse location
     * @param clickCount     the number of mouse clicks associated with event
     * @param popupTrigger   a boolean, true if this event is a trigger for a
     *                       popup-menu
     * @param scrollType     the type of scrolling which should take place in
     *                       response to this event;  valid values are
     *                       <code>WHEEL_UNIT_SCROLL</code> and
     *                       <code>WHEEL_BLOCK_SCROLL</code>
     * @param  scrollAmount  for scrollType <code>WHEEL_UNIT_SCROLL</code>,
     *                       the number of units to be scrolled
     * @param wheelRotation  the integer number of "clicks" by which the mouse
     *                       wheel was rotated
     *
     * @throws IllegalArgumentException if <code>source</code> is null
     * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, boolean)
     * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, int, int, boolean, int)
     */
    public MouseWheelEvent (Component source, int id, long when, int modifiers,
                      int x, int y, int clickCount, boolean popupTrigger,
                      int scrollType, int scrollAmount, int wheelRotation) {

        this(source, id, when, modifiers, x, y, 0, 0, clickCount,
             popupTrigger, scrollType, scrollAmount, wheelRotation);
    }

    
Constructs a MouseWheelEvent object with the
specified source component, type, modifiers, coordinates,
absolute coordinates, scroll type, scroll amount, and wheel rotation.

Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.

Even if inconsistent values for relative and absolute coordinates are
passed to the constructor, the MouseWheelEvent instance is still
created and no exception is thrown.

Params:
  • source –         the Component that originated
                      the event
  • id –             the integer that identifies the event
  • when –           a long that gives the time the event occurred
  • modifiers –      the modifier keys down during event
                      (shift, ctrl, alt, meta)
  • x –              the horizontal x coordinate for the mouse location
  • y –              the vertical y coordinate for the mouse location
  • xAbs –           the absolute horizontal x coordinate for the mouse location
  • yAbs –           the absolute vertical y coordinate for the mouse location
  • clickCount –     the number of mouse clicks associated with event
  • popupTrigger –   a boolean, true if this event is a trigger for a
                      popup-menu
  • scrollType –     the type of scrolling which should take place in
                      response to this event;  valid values are
                      WHEEL_UNIT_SCROLL and
                      WHEEL_BLOCK_SCROLL
  • scrollAmount –  for scrollType WHEEL_UNIT_SCROLL,
                      the number of units to be scrolled
  • wheelRotation –  the integer number of "clicks" by which the mouse
                      wheel was rotated
Throws:
See Also:
Since:1.6
/**
     * Constructs a <code>MouseWheelEvent</code> object with the
     * specified source component, type, modifiers, coordinates,
     * absolute coordinates, scroll type, scroll amount, and wheel rotation.
     * <p>Note that passing in an invalid <code>id</code> results in
     * unspecified behavior. This method throws an
     * <code>IllegalArgumentException</code> if <code>source</code>
     * is <code>null</code>.<p>
     * Even if inconsistent values for relative and absolute coordinates are
     * passed to the constructor, the MouseWheelEvent instance is still
     * created and no exception is thrown.
     *
     * @param source         the <code>Component</code> that originated
     *                       the event
     * @param id             the integer that identifies the event
     * @param when           a long that gives the time the event occurred
     * @param modifiers      the modifier keys down during event
     *                       (shift, ctrl, alt, meta)
     * @param x              the horizontal x coordinate for the mouse location
     * @param y              the vertical y coordinate for the mouse location
     * @param xAbs           the absolute horizontal x coordinate for the mouse location
     * @param yAbs           the absolute vertical y coordinate for the mouse location
     * @param clickCount     the number of mouse clicks associated with event
     * @param popupTrigger   a boolean, true if this event is a trigger for a
     *                       popup-menu
     * @param scrollType     the type of scrolling which should take place in
     *                       response to this event;  valid values are
     *                       <code>WHEEL_UNIT_SCROLL</code> and
     *                       <code>WHEEL_BLOCK_SCROLL</code>
     * @param  scrollAmount  for scrollType <code>WHEEL_UNIT_SCROLL</code>,
     *                       the number of units to be scrolled
     * @param wheelRotation  the integer number of "clicks" by which the mouse
     *                       wheel was rotated
     *
     * @throws IllegalArgumentException if <code>source</code> is null
     * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, boolean)
     * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, int, int, boolean, int)
     * @since 1.6
     */
    public MouseWheelEvent (Component source, int id, long when, int modifiers,
                            int x, int y, int xAbs, int yAbs, int clickCount, boolean popupTrigger,
                            int scrollType, int scrollAmount, int wheelRotation) {

        this(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount, popupTrigger,
             scrollType, scrollAmount, wheelRotation, wheelRotation);

    }


    
Constructs a MouseWheelEvent object with the specified
source component, type, modifiers, coordinates, absolute coordinates,
scroll type, scroll amount, and wheel rotation.

Note that passing in an invalid id parameter results
in unspecified behavior. This method throws an
IllegalArgumentException if source equals
null.

Even if inconsistent values for relative and absolute coordinates
are passed to the constructor, a MouseWheelEvent instance
is still created and no exception is thrown.

Params:
  • source –         the Component that originated the event
  • id –             the integer value that identifies the event
  • when –           a long value that gives the time when the event occurred
  • modifiers –      the modifier keys down during event
                      (shift, ctrl, alt, meta)
  • x –              the horizontal x coordinate for the
                      mouse location
  • y –              the vertical y coordinate for the
                      mouse location
  • xAbs –           the absolute horizontal x coordinate for
                      the mouse location
  • yAbs –           the absolute vertical y coordinate for
                      the mouse location
  • clickCount –     the number of mouse clicks associated with the event
  • popupTrigger –   a boolean value, true if this event is a trigger
                      for a popup-menu
  • scrollType –     the type of scrolling which should take place in
                      response to this event;  valid values are
                      WHEEL_UNIT_SCROLL and
                      WHEEL_BLOCK_SCROLL
  • scrollAmount –  for scrollType WHEEL_UNIT_SCROLL,
                      the number of units to be scrolled
  • wheelRotation –  the integer number of "clicks" by which the mouse wheel
                      was rotated
  • preciseWheelRotation – the double number of "clicks" by which the mouse wheel
                      was rotated
Throws:
See Also:
Since:1.7
/**
     * Constructs a <code>MouseWheelEvent</code> object with the specified
     * source component, type, modifiers, coordinates, absolute coordinates,
     * scroll type, scroll amount, and wheel rotation.
     * <p>Note that passing in an invalid <code>id</code> parameter results
     * in unspecified behavior. This method throws an
     * <code>IllegalArgumentException</code> if <code>source</code> equals
     * <code>null</code>.
     * <p>Even if inconsistent values for relative and absolute coordinates
     * are passed to the constructor, a <code>MouseWheelEvent</code> instance
     * is still created and no exception is thrown.
     *
     * @param source         the <code>Component</code> that originated the event
     * @param id             the integer value that identifies the event
     * @param when           a long value that gives the time when the event occurred
     * @param modifiers      the modifier keys down during event
     *                       (shift, ctrl, alt, meta)
     * @param x              the horizontal <code>x</code> coordinate for the
     *                       mouse location
     * @param y              the vertical <code>y</code> coordinate for the
     *                       mouse location
     * @param xAbs           the absolute horizontal <code>x</code> coordinate for
     *                       the mouse location
     * @param yAbs           the absolute vertical <code>y</code> coordinate for
     *                       the mouse location
     * @param clickCount     the number of mouse clicks associated with the event
     * @param popupTrigger   a boolean value, <code>true</code> if this event is a trigger
     *                       for a popup-menu
     * @param scrollType     the type of scrolling which should take place in
     *                       response to this event;  valid values are
     *                       <code>WHEEL_UNIT_SCROLL</code> and
     *                       <code>WHEEL_BLOCK_SCROLL</code>
     * @param  scrollAmount  for scrollType <code>WHEEL_UNIT_SCROLL</code>,
     *                       the number of units to be scrolled
     * @param wheelRotation  the integer number of "clicks" by which the mouse wheel
     *                       was rotated
     * @param preciseWheelRotation the double number of "clicks" by which the mouse wheel
     *                       was rotated
     *
     * @throws IllegalArgumentException if <code>source</code> is null
     * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, boolean)
     * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, int, int, boolean, int)
     * @since 1.7
     */
    public MouseWheelEvent (Component source, int id, long when, int modifiers,
                            int x, int y, int xAbs, int yAbs, int clickCount, boolean popupTrigger,
                            int scrollType, int scrollAmount, int wheelRotation, double preciseWheelRotation) {

        super(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount,
              popupTrigger, MouseEvent.NOBUTTON);

        this.scrollType = scrollType;
        this.scrollAmount = scrollAmount;
        this.wheelRotation = wheelRotation;
        this.preciseWheelRotation = preciseWheelRotation;

    }

    
Returns the type of scrolling that should take place in response to this
event.  This is determined by the native platform.  Legal values are:

    

  •  MouseWheelEvent.WHEEL_UNIT_SCROLL

  •  MouseWheelEvent.WHEEL_BLOCK_SCROLL



See Also:
Returns:either MouseWheelEvent.WHEEL_UNIT_SCROLL or
 MouseWheelEvent.WHEEL_BLOCK_SCROLL, depending on the configuration of
 the native platform.
/**
     * Returns the type of scrolling that should take place in response to this
     * event.  This is determined by the native platform.  Legal values are:
     * <ul>
     * <li> MouseWheelEvent.WHEEL_UNIT_SCROLL
     * <li> MouseWheelEvent.WHEEL_BLOCK_SCROLL
     * </ul>
     *
     * @return either MouseWheelEvent.WHEEL_UNIT_SCROLL or
     *  MouseWheelEvent.WHEEL_BLOCK_SCROLL, depending on the configuration of
     *  the native platform.
     * @see java.awt.Adjustable#getUnitIncrement
     * @see java.awt.Adjustable#getBlockIncrement
     * @see javax.swing.Scrollable#getScrollableUnitIncrement
     * @see javax.swing.Scrollable#getScrollableBlockIncrement
     */
    public int getScrollType() {
        return scrollType;
    }

    
Returns the number of units that should be scrolled per
click of mouse wheel rotation.
Only valid if getScrollType returns
MouseWheelEvent.WHEEL_UNIT_SCROLL

See Also:
Returns:number of units to scroll, or an undefined value if
 getScrollType returns
 MouseWheelEvent.WHEEL_BLOCK_SCROLL
/**
     * Returns the number of units that should be scrolled per
     * click of mouse wheel rotation.
     * Only valid if <code>getScrollType</code> returns
     * <code>MouseWheelEvent.WHEEL_UNIT_SCROLL</code>
     *
     * @return number of units to scroll, or an undefined value if
     *  <code>getScrollType</code> returns
     *  <code>MouseWheelEvent.WHEEL_BLOCK_SCROLL</code>
     * @see #getScrollType
     */
    public int getScrollAmount() {
        return scrollAmount;
    }

    
Returns the number of "clicks" the mouse wheel was rotated, as an integer.
A partial rotation may occur if the mouse supports a high-resolution wheel.
In this case, the method returns zero until a full "click" has been accumulated.

See Also:
Returns:negative values if the mouse wheel was rotated up/away from
the user, and positive values if the mouse wheel was rotated down/
towards the user
/**
     * Returns the number of "clicks" the mouse wheel was rotated, as an integer.
     * A partial rotation may occur if the mouse supports a high-resolution wheel.
     * In this case, the method returns zero until a full "click" has been accumulated.
     *
     * @return negative values if the mouse wheel was rotated up/away from
     * the user, and positive values if the mouse wheel was rotated down/
     * towards the user
     * @see #getPreciseWheelRotation
     */
    public int getWheelRotation() {
        return wheelRotation;
    }

    
Returns the number of "clicks" the mouse wheel was rotated, as a double.
A partial rotation may occur if the mouse supports a high-resolution wheel.
In this case, the return value will include a fractional "click".

See Also:
Returns:negative values if the mouse wheel was rotated up or away from
the user, and positive values if the mouse wheel was rotated down or
towards the user
Since:1.7
/**
     * Returns the number of "clicks" the mouse wheel was rotated, as a double.
     * A partial rotation may occur if the mouse supports a high-resolution wheel.
     * In this case, the return value will include a fractional "click".
     *
     * @return negative values if the mouse wheel was rotated up or away from
     * the user, and positive values if the mouse wheel was rotated down or
     * towards the user
     * @see #getWheelRotation
     * @since 1.7
     */
    public double getPreciseWheelRotation() {
        return preciseWheelRotation;
    }

    
This is a convenience method to aid in the implementation of
the common-case MouseWheelListener - to scroll a ScrollPane or
JScrollPane by an amount which conforms to the platform settings.
(Note, however, that ScrollPane and
JScrollPane already have this functionality built in.)


This method returns the number of units to scroll when scroll type is
MouseWheelEvent.WHEEL_UNIT_SCROLL, and should only be called if
getScrollType returns MouseWheelEvent.WHEEL_UNIT_SCROLL.


Direction of scroll, amount of wheel movement,
and platform settings for wheel scrolling are all accounted for.
This method does not and cannot take into account value of the
Adjustable/Scrollable unit increment, as this will vary among
scrolling components.


A simplified example of how this method might be used in a
listener:

 mouseWheelMoved(MouseWheelEvent event) {
     ScrollPane sp = getScrollPaneFromSomewhere();
     Adjustable adj = sp.getVAdjustable()
     if (MouseWheelEvent.getScrollType() == WHEEL_UNIT_SCROLL) {
         int totalScrollAmount =
             event.getUnitsToScroll() *
             adj.getUnitIncrement();
         adj.setValue(adj.getValue() + totalScrollAmount);
     }
 }



See Also:
Returns:the number of units to scroll based on the direction and amount
 of mouse wheel rotation, and on the wheel scrolling settings of the
 native platform
/**
     * This is a convenience method to aid in the implementation of
     * the common-case MouseWheelListener - to scroll a ScrollPane or
     * JScrollPane by an amount which conforms to the platform settings.
     * (Note, however, that <code>ScrollPane</code> and
     * <code>JScrollPane</code> already have this functionality built in.)
     * <P>
     * This method returns the number of units to scroll when scroll type is
     * MouseWheelEvent.WHEEL_UNIT_SCROLL, and should only be called if
     * <code>getScrollType</code> returns MouseWheelEvent.WHEEL_UNIT_SCROLL.
     * <P>
     * Direction of scroll, amount of wheel movement,
     * and platform settings for wheel scrolling are all accounted for.
     * This method does not and cannot take into account value of the
     * Adjustable/Scrollable unit increment, as this will vary among
     * scrolling components.
     * <P>
     * A simplified example of how this method might be used in a
     * listener:
     * <pre>
     *  mouseWheelMoved(MouseWheelEvent event) {
     *      ScrollPane sp = getScrollPaneFromSomewhere();
     *      Adjustable adj = sp.getVAdjustable()
     *      if (MouseWheelEvent.getScrollType() == WHEEL_UNIT_SCROLL) {
     *          int totalScrollAmount =
     *              event.getUnitsToScroll() *
     *              adj.getUnitIncrement();
     *          adj.setValue(adj.getValue() + totalScrollAmount);
     *      }
     *  }
     * </pre>
     *
     * @return the number of units to scroll based on the direction and amount
     *  of mouse wheel rotation, and on the wheel scrolling settings of the
     *  native platform
     * @see #getScrollType
     * @see #getScrollAmount
     * @see MouseWheelListener
     * @see java.awt.Adjustable
     * @see java.awt.Adjustable#getUnitIncrement
     * @see javax.swing.Scrollable
     * @see javax.swing.Scrollable#getScrollableUnitIncrement
     * @see java.awt.ScrollPane
     * @see java.awt.ScrollPane#setWheelScrollingEnabled
     * @see javax.swing.JScrollPane
     * @see javax.swing.JScrollPane#setWheelScrollingEnabled
     */
    public int getUnitsToScroll() {
        return scrollAmount * wheelRotation;
    }

    
Returns a parameter string identifying this event.
This method is useful for event-logging and for debugging.

Returns:a string identifying the event and its attributes
/**
     * Returns a parameter string identifying this event.
     * This method is useful for event-logging and for debugging.
     *
     * @return a string identifying the event and its attributes
     */
    public String paramString() {
        String scrollTypeStr = null;

        if (getScrollType() == WHEEL_UNIT_SCROLL) {
            scrollTypeStr = "WHEEL_UNIT_SCROLL";
        }
        else if (getScrollType() == WHEEL_BLOCK_SCROLL) {
            scrollTypeStr = "WHEEL_BLOCK_SCROLL";
        }
        else {
            scrollTypeStr = "unknown scroll type";
        }
        return super.paramString()+",scrollType="+scrollTypeStr+
         ",scrollAmount="+getScrollAmount()+",wheelRotation="+
         getWheelRotation()+",preciseWheelRotation="+getPreciseWheelRotation();
    }
}