1 /* MouseWheelEvent.java -- a mouse wheel event 2 Copyright (C) 2002, 2005 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package java.awt.event; 40 41 import java.awt.Adjustable; 42 import java.awt.Component; 43 import java.awt.Rectangle; 44 import java.awt.ScrollPane; 45 46 import javax.swing.JScrollPane; 47 import javax.swing.Scrollable; 48 49 /** 50 * This event is generated for a mouse wheel rotation. The wheel (the middle 51 * mouse button on most modern mice) can be rotated towards or away from the 52 * user, and is often used for scrolling. 53 * 54 * <p>Because of the special use for scrolling components, MouseWheelEvents 55 * often affect a different component than the one located at the point of 56 * the event. If the component under the mouse cursor does not accept wheel 57 * events, the event is passed to the first ancestor container which does. This 58 * is often a ScrollPane, which knows how to scroll. If an AWT component is 59 * built from a native widget that knows how to use mouse wheel events, that 60 * component will consume the event. 61 * 62 * <p>The two most common scroll types are "units" (lines at a time) or 63 * "blocks" (pages at a time). The initial setting is taken from the platform, 64 * although the user can adjust the setting at any time. 65 * 66 * @author Eric Blake (ebb9@email.byu.edu) 67 * @see MouseWheelListener 68 * @see ScrollPane 69 * @see ScrollPane#setWheelScrollingEnabled(boolean) 70 * @see JScrollPane 71 * @see JScrollPane#setWheelScrollingEnabled(boolean) 72 * @since 1.4 73 * @status updated to 1.4 74 */ 75 public class MouseWheelEvent extends MouseEvent 76 { 77 /** 78 * Compatible with JDK 1.4+. 79 */ 80 private static final long serialVersionUID = 6459879390515399677L; 81 82 /** 83 * Indicates scrolling by units (lines). 84 * 85 * @see #getScrollType() 86 */ 87 public static final int WHEEL_UNIT_SCROLL = 0; 88 89 /** 90 * Indicates scrolling by blocks (pages). 91 * 92 * @see #getScrollType() 93 */ 94 public static final int WHEEL_BLOCK_SCROLL = 1; 95 96 /** 97 * Indicates what scroll type should take place. This should be limited 98 * to {@link #WHEEL_UNIT_SCROLL} and {@link #WHEEL_BLOCK_SCROLL}. 99 * 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 */ MouseWheelEvent(Component source, int id, long when, int modifiers, int x, int y, int clickCount, boolean popupTrigger, int scrollType, int scrollAmount, int wheelRotation)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 */ getScrollType()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 */ getScrollAmount()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 */ getWheelRotation()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 */ getUnitsToScroll()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 */ paramString()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 233