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package java.awt.event;

import java.awt.Component;

/**

 * 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 #getScrollType

     */

    /**

     * Constant representing scrolling by a "block" (like scrolling

     * with page-up, page-down keys)

     *

     * @see #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 #getScrollAmount

     * @see #getScrollType

     */

    int scrollAmount;

    /**

     * Indicates how far the mouse wheel was rotated.

     *

     * @see #getWheelRotation

     */

    int wheelRotation;

    /**

     * Indicates how far the mouse wheel was rotated.

     *

     * @see #getPreciseWheelRotation

     */

    double preciseWheelRotation;

    /*

     * serialVersionUID

     */

    private static final long serialVersionUID = 6459879390515399677L;

    /**

     * 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 <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 <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:

     * <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 <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.

     *

     * @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".

     *

     * @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 <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.

     *

     * @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();

    }

}