/* * Copyright 2000-2006 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Sun designates this * particular file as subject to the "Classpath" exception as provided * by Sun in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. */ package java.awt.event; import java.awt.Component; /** * 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. * * @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 */ public static final int WHEEL_UNIT_SCROLL = 0; /** * Constant representing scrolling by a "block" (like scrolling * with page-up, page-down keys) * * @see #getScrollType */ 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: *

* * @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; /* * 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. * * @param source the Component 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 * WHEEL_UNIT_SCROLL and * WHEEL_BLOCK_SCROLL * @param scrollAmount for scrollType WHEEL_UNIT_SCROLL, * the number of units to be scrolled * @param wheelRotation the amount that the mouse wheel was rotated (the * number of "clicks") * * @throws IllegalArgumentException if source 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. * * @param source the Component 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 * WHEEL_UNIT_SCROLL and * WHEEL_BLOCK_SCROLL * @param scrollAmount for scrollType WHEEL_UNIT_SCROLL, * the number of units to be scrolled * @param wheelRotation the amount that the mouse wheel was rotated (the * number of "clicks") * * @throws IllegalArgumentException if source 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) { super(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount, popupTrigger, MouseEvent.NOBUTTON); this.scrollType = scrollType; this.scrollAmount = scrollAmount; this.wheelRotation = wheelRotation; } /** * Returns the type of scrolling that should take place in response to this * event. This is determined by the native platform. Legal values are: *

* * @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 * * @return number of units to scroll, or an undefined value if * getScrollType returns * MouseWheelEvent.WHEEL_BLOCK_SCROLL * @see #getScrollType */ public int getScrollAmount() { return scrollAmount; } /** * Returns the number of "clicks" the mouse wheel was rotated. * * @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 */ public int getWheelRotation() { return wheelRotation; } /** * 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);
     *      }
     *  }
     *
* * @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(); } }