001/* MouseWheelEvent.java -- a mouse wheel event 002 Copyright (C) 2002, 2005 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package java.awt.event; 040 041import java.awt.Adjustable; 042import java.awt.Component; 043import java.awt.Rectangle; 044import java.awt.ScrollPane; 045 046import javax.swing.JScrollPane; 047import javax.swing.Scrollable; 048 049/** 050 * This event is generated for a mouse wheel rotation. The wheel (the middle 051 * mouse button on most modern mice) can be rotated towards or away from the 052 * user, and is often used for scrolling. 053 * 054 * <p>Because of the special use for scrolling components, MouseWheelEvents 055 * often affect a different component than the one located at the point of 056 * the event. If the component under the mouse cursor does not accept wheel 057 * events, the event is passed to the first ancestor container which does. This 058 * is often a ScrollPane, which knows how to scroll. If an AWT component is 059 * built from a native widget that knows how to use mouse wheel events, that 060 * component will consume the event. 061 * 062 * <p>The two most common scroll types are "units" (lines at a time) or 063 * "blocks" (pages at a time). The initial setting is taken from the platform, 064 * although the user can adjust the setting at any time. 065 * 066 * @author Eric Blake (ebb9@email.byu.edu) 067 * @see MouseWheelListener 068 * @see ScrollPane 069 * @see ScrollPane#setWheelScrollingEnabled(boolean) 070 * @see JScrollPane 071 * @see JScrollPane#setWheelScrollingEnabled(boolean) 072 * @since 1.4 073 * @status updated to 1.4 074 */ 075public class MouseWheelEvent extends MouseEvent 076{ 077 /** 078 * Compatible with JDK 1.4+. 079 */ 080 private static final long serialVersionUID = 6459879390515399677L; 081 082 /** 083 * Indicates scrolling by units (lines). 084 * 085 * @see #getScrollType() 086 */ 087 public static final int WHEEL_UNIT_SCROLL = 0; 088 089 /** 090 * Indicates scrolling by blocks (pages). 091 * 092 * @see #getScrollType() 093 */ 094 public static final int WHEEL_BLOCK_SCROLL = 1; 095 096 /** 097 * Indicates what scroll type should take place. This should be limited 098 * to {@link #WHEEL_UNIT_SCROLL} and {@link #WHEEL_BLOCK_SCROLL}. 099 * 100 * @serial the scroll type 101 */ 102 private final int scrollType; 103 104 /** 105 * Indicates the scroll amount. This is only meaningful if scrollType is 106 * WHEEL_UNIT_SCROLL. 107 * 108 * @serial the number of lines to scroll 109 */ 110 private final int scrollAmount; 111 112 /** 113 * Indicates how far the mouse wheel was rotated. 114 * 115 * @serial the rotation amount 116 */ 117 private final int wheelRotation; 118 119 /** 120 * Initializes a new instance of <code>MouseWheelEvent</code> with the 121 * specified information. Note that an invalid id leads to unspecified 122 * results. 123 * 124 * @param source the source of the event 125 * @param id the event id 126 * @param when the timestamp of when the event occurred 127 * @param modifiers any modifier bits for this event 128 * @param x the X coordinate of the mouse point 129 * @param y the Y coordinate of the mouse point 130 * @param clickCount the number of mouse clicks for this event 131 * @param popupTrigger true if this event triggers a popup menu 132 * @param scrollType one of {@link #WHEEL_UNIT_SCROLL}, 133 * {@link #WHEEL_BLOCK_SCROLL} 134 * @param scrollAmount the number of units to scroll, ignored for block type 135 * @param wheelRotation the number of rotation "clicks" 136 * @throws IllegalArgumentException if source is null 137 * @see MouseEvent#MouseEvent(Component, int, long, int, int, int, int, 138 * boolean) 139 */ 140 public MouseWheelEvent(Component source, int id, long when, int modifiers, 141 int x, int y, int clickCount, boolean popupTrigger, 142 int scrollType, int scrollAmount, int wheelRotation) 143 { 144 super(source, id, when, modifiers, x, y, clickCount, popupTrigger); 145 this.scrollType = scrollType; 146 this.scrollAmount = scrollAmount; 147 this.wheelRotation = wheelRotation; 148 } 149 150 /** 151 * This method returns the scrolling pattern this event requests. Legal 152 * values are {@link #WHEEL_UNIT_SCROLL} and {@link #WHEEL_BLOCK_SCROLL}. 153 * 154 * @return the scroll type 155 * @see Adjustable#getUnitIncrement() 156 * @see Adjustable#getBlockIncrement() 157 * @see Scrollable#getScrollableUnitIncrement(Rectangle, int, int) 158 * @see Scrollable#getScrollableBlockIncrement(Rectangle, int, int) 159 */ 160 public int getScrollType() 161 { 162 return scrollType; 163 } 164 165 /** 166 * Returns the number of units to scroll in response to this event. This 167 * only makes sense when the scroll type is WHEEL_UNIT_SCROLL. 168 * 169 * @return the number of scroll units, if defined 170 * @see #getScrollType() 171 */ 172 public int getScrollAmount() 173 { 174 return scrollAmount; 175 } 176 177 /** 178 * Gets the number of "clicks" the wheel was rotated. Negative values move 179 * up (away) from the user, positive values move down (towards) the user. 180 * 181 * @return the number of rotation clicks 182 */ 183 public int getWheelRotation() 184 { 185 return wheelRotation; 186 } 187 188 /** 189 * This is a convenience method which aids in a common listener for scrolling 190 * a scrollpane (although this is already built into ScrollPane and 191 * JScrollPane). This method only makes sense when getScrollType() returns 192 * WHEEL_UNIT_SCROLL. 193 * 194 * <p>This accounts for direction of scroll and amount of wheel movement, as 195 * interpreted by the platform settings. 196 * 197 * @return the number of units to scroll 198 * @see #getScrollType() 199 * @see #getScrollAmount() 200 * @see MouseWheelListener 201 * @see Adjustable 202 * @see Adjustable#getUnitIncrement() 203 * @see Scrollable 204 * @see Scrollable#getScrollableUnitIncrement(Rectangle, int, int) 205 * @see ScrollPane 206 * @see ScrollPane#setWheelScrollingEnabled(boolean) 207 * @see JScrollPane 208 * @see JScrollPane#setWheelScrollingEnabled(boolean) 209 */ 210 public int getUnitsToScroll() 211 { 212 return wheelRotation * scrollAmount; 213 } 214 215 /** 216 * Returns a string identifying this event. For mouse wheel events, this 217 * is <code>super.paramString() + ",scrollType=WHEEL_" + 218 * (getScrollType() == WHEEL_UNIT_SCROLL ? "UNIT" : "BLOCK") 219 * + "_SCROLL,scrollAmount=" + getScrollAmount() + ",wheelRotation=" 220 * + getWheelRotation()</code>. 221 * 222 * @return a string identifying this event 223 */ 224 public String paramString() 225 { 226 return super.paramString() + ",scrollType=" 227 + (scrollType == WHEEL_UNIT_SCROLL ? "WHEEL_UNIT_SCROLL" 228 : scrollType == WHEEL_BLOCK_SCROLL ? "WHEEL_BLOCK_SCROLL" 229 : "unknown scroll type") 230 + ",scrollAmount=" + scrollAmount + ",wheelRotation=" + wheelRotation; 231 } 232} // class MouseWheelEvent