1 /*
2 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.awt.event;
27
28 import java.awt.Component;
29
30 import java.lang.annotation.Native;
31
32 /**
33 * An event which indicates that the mouse wheel was rotated in a component.
34 * <P>
35 * A wheel mouse is a mouse which has a wheel in place of the middle button.
36 * This wheel can be rotated towards or away from the user. Mouse wheels are
37 * most often used for scrolling, though other uses are possible.
38 * <P>
39 * A MouseWheelEvent object is passed to every <code>MouseWheelListener</code>
40 * object which registered to receive the "interesting" mouse events using the
41 * component's <code>addMouseWheelListener</code> method. Each such listener
42 * object gets a <code>MouseEvent</code> containing the mouse event.
43 * <P>
44 * Due to the mouse wheel's special relationship to scrolling Components,
45 * MouseWheelEvents are delivered somewhat differently than other MouseEvents.
46 * This is because while other MouseEvents usually affect a change on
47 * the Component directly under the mouse
48 * cursor (for instance, when clicking a button), MouseWheelEvents often have
49 * an effect away from the mouse cursor (moving the wheel while
50 * over a Component inside a ScrollPane should scroll one of the
51 * Scrollbars on the ScrollPane).
52 * <P>
53 * MouseWheelEvents start delivery from the Component underneath the
54 * mouse cursor. If MouseWheelEvents are not enabled on the
55 * Component, the event is delivered to the first ancestor
56 * Container with MouseWheelEvents enabled. This will usually be
57 * a ScrollPane with wheel scrolling enabled. The source
58 * Component and x,y coordinates will be relative to the event's
59 * final destination (the ScrollPane). This allows a complex
60 * GUI to be installed without modification into a ScrollPane, and
61 * for all MouseWheelEvents to be delivered to the ScrollPane for
62 * scrolling.
63 * <P>
64 * Some AWT Components are implemented using native widgets which
65 * display their own scrollbars and handle their own scrolling.
66 * The particular Components for which this is true will vary from
67 * platform to platform. When the mouse wheel is
68 * moved over one of these Components, the event is delivered straight to
69 * the native widget, and not propagated to ancestors.
70 * <P>
71 * Platforms offer customization of the amount of scrolling that
72 * should take place when the mouse wheel is moved. The two most
73 * common settings are to scroll a certain number of "units"
74 * (commonly lines of text in a text-based component) or an entire "block"
75 * (similar to page-up/page-down). The MouseWheelEvent offers
76 * methods for conforming to the underlying platform settings. These
77 * platform settings can be changed at any time by the user. MouseWheelEvents
78 * reflect the most recent settings.
79 * <P>
80 * The <code>MouseWheelEvent</code> class includes methods for
81 * getting the number of "clicks" by which the mouse wheel is rotated.
82 * The {@link #getWheelRotation} method returns the integer number
83 * of "clicks" corresponding to the number of notches by which the wheel was
84 * rotated. In addition to this method, the <code>MouseWheelEvent</code>
85 * class provides the {@link #getPreciseWheelRotation} method which returns
86 * a double number of "clicks" in case a partial rotation occurred.
87 * The {@link #getPreciseWheelRotation} method is useful if a mouse supports
88 * a high-resolution wheel, such as a freely rotating wheel with no
89 * notches. Applications can benefit by using this method to process
90 * mouse wheel events more precisely, and thus, making visual perception
91 * smoother.
92 *
93 * @author Brent Christian
94 * @see MouseWheelListener
95 * @see java.awt.ScrollPane
96 * @see java.awt.ScrollPane#setWheelScrollingEnabled(boolean)
97 * @see javax.swing.JScrollPane
98 * @see javax.swing.JScrollPane#setWheelScrollingEnabled(boolean)
99 * @since 1.4
100 */
101
102 public class MouseWheelEvent extends MouseEvent {
103
104 /**
105 * Constant representing scrolling by "units" (like scrolling with the
106 * arrow keys)
107 *
108 * @see #getScrollType
109 */
110 @Native public static final int WHEEL_UNIT_SCROLL = 0;
111
112 /**
113 * Constant representing scrolling by a "block" (like scrolling
114 * with page-up, page-down keys)
115 *
116 * @see #getScrollType
117 */
118 @Native public static final int WHEEL_BLOCK_SCROLL = 1;
119
120 /**
121 * Indicates what sort of scrolling should take place in response to this
122 * event, based on platform settings. Legal values are:
123 * <ul>
124 * <li> WHEEL_UNIT_SCROLL
125 * <li> WHEEL_BLOCK_SCROLL
126 * </ul>
127 *
128 * @see #getScrollType
129 */
130 int scrollType;
131
132 /**
133 * Only valid for scrollType WHEEL_UNIT_SCROLL.
134 * Indicates number of units that should be scrolled per
135 * click of mouse wheel rotation, based on platform settings.
136 *
137 * @see #getScrollAmount
138 * @see #getScrollType
139 */
140 int scrollAmount;
141
142 /**
143 * Indicates how far the mouse wheel was rotated.
144 *
145 * @see #getWheelRotation
146 */
147 int wheelRotation;
148
149 /**
150 * Indicates how far the mouse wheel was rotated.
151 *
152 * @see #getPreciseWheelRotation
153 */
154 double preciseWheelRotation;
155
156 /*
157 * serialVersionUID
158 */
159
160 private static final long serialVersionUID = 6459879390515399677L;
161
162 /**
163 * Constructs a <code>MouseWheelEvent</code> object with the
164 * specified source component, type, modifiers, coordinates,
165 * scroll type, scroll amount, and wheel rotation.
166 * <p>Absolute coordinates xAbs and yAbs are set to source's location on screen plus
167 * relative coordinates x and y. xAbs and yAbs are set to zero if the source is not showing.
168 * <p>Note that passing in an invalid <code>id</code> results in
169 * unspecified behavior. This method throws an
170 * <code>IllegalArgumentException</code> if <code>source</code>
171 * is <code>null</code>.
172 *
173 * @param source the <code>Component</code> that originated
174 * the event
175 * @param id the integer that identifies the event
176 * @param when a long that gives the time the event occurred
177 * @param modifiers the modifier keys down during event
178 * (shift, ctrl, alt, meta)
179 * @param x the horizontal x coordinate for the mouse location
180 * @param y the vertical y coordinate for the mouse location
181 * @param clickCount the number of mouse clicks associated with event
182 * @param popupTrigger a boolean, true if this event is a trigger for a
183 * popup-menu
184 * @param scrollType the type of scrolling which should take place in
185 * response to this event; valid values are
186 * <code>WHEEL_UNIT_SCROLL</code> and
187 * <code>WHEEL_BLOCK_SCROLL</code>
188 * @param scrollAmount for scrollType <code>WHEEL_UNIT_SCROLL</code>,
189 * the number of units to be scrolled
190 * @param wheelRotation the integer number of "clicks" by which the mouse
191 * wheel was rotated
192 *
193 * @throws IllegalArgumentException if <code>source</code> is null
194 * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, boolean)
195 * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, int, int, boolean, int)
196 */
197 public MouseWheelEvent (Component source, int id, long when, int modifiers,
198 int x, int y, int clickCount, boolean popupTrigger,
199 int scrollType, int scrollAmount, int wheelRotation) {
200
201 this(source, id, when, modifiers, x, y, 0, 0, clickCount,
202 popupTrigger, scrollType, scrollAmount, wheelRotation);
203 }
204
205 /**
206 * Constructs a <code>MouseWheelEvent</code> object with the
207 * specified source component, type, modifiers, coordinates,
208 * absolute coordinates, scroll type, scroll amount, and wheel rotation.
209 * <p>Note that passing in an invalid <code>id</code> results in
210 * unspecified behavior. This method throws an
211 * <code>IllegalArgumentException</code> if <code>source</code>
212 * is <code>null</code>.<p>
213 * Even if inconsistent values for relative and absolute coordinates are
214 * passed to the constructor, the MouseWheelEvent instance is still
215 * created and no exception is thrown.
216 *
217 * @param source the <code>Component</code> that originated
218 * the event
219 * @param id the integer that identifies the event
220 * @param when a long that gives the time the event occurred
221 * @param modifiers the modifier keys down during event
222 * (shift, ctrl, alt, meta)
223 * @param x the horizontal x coordinate for the mouse location
224 * @param y the vertical y coordinate for the mouse location
225 * @param xAbs the absolute horizontal x coordinate for the mouse location
226 * @param yAbs the absolute vertical y coordinate for the mouse location
227 * @param clickCount the number of mouse clicks associated with event
228 * @param popupTrigger a boolean, true if this event is a trigger for a
229 * popup-menu
230 * @param scrollType the type of scrolling which should take place in
231 * response to this event; valid values are
232 * <code>WHEEL_UNIT_SCROLL</code> and
233 * <code>WHEEL_BLOCK_SCROLL</code>
234 * @param scrollAmount for scrollType <code>WHEEL_UNIT_SCROLL</code>,
235 * the number of units to be scrolled
236 * @param wheelRotation the integer number of "clicks" by which the mouse
237 * wheel was rotated
238 *
239 * @throws IllegalArgumentException if <code>source</code> is null
240 * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, boolean)
241 * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, int, int, boolean, int)
242 * @since 1.6
243 */
244 public MouseWheelEvent (Component source, int id, long when, int modifiers,
245 int x, int y, int xAbs, int yAbs, int clickCount, boolean popupTrigger,
246 int scrollType, int scrollAmount, int wheelRotation) {
247
248 this(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount, popupTrigger,
249 scrollType, scrollAmount, wheelRotation, wheelRotation);
250
251 }
252
253
254 /**
255 * Constructs a <code>MouseWheelEvent</code> object with the specified
256 * source component, type, modifiers, coordinates, absolute coordinates,
257 * scroll type, scroll amount, and wheel rotation.
258 * <p>Note that passing in an invalid <code>id</code> parameter results
259 * in unspecified behavior. This method throws an
260 * <code>IllegalArgumentException</code> if <code>source</code> equals
261 * <code>null</code>.
262 * <p>Even if inconsistent values for relative and absolute coordinates
263 * are passed to the constructor, a <code>MouseWheelEvent</code> instance
264 * is still created and no exception is thrown.
265 *
266 * @param source the <code>Component</code> that originated the event
267 * @param id the integer value that identifies the event
268 * @param when a long value that gives the time when the event occurred
269 * @param modifiers the modifier keys down during event
270 * (shift, ctrl, alt, meta)
271 * @param x the horizontal <code>x</code> coordinate for the
272 * mouse location
273 * @param y the vertical <code>y</code> coordinate for the
274 * mouse location
275 * @param xAbs the absolute horizontal <code>x</code> coordinate for
276 * the mouse location
277 * @param yAbs the absolute vertical <code>y</code> coordinate for
278 * the mouse location
279 * @param clickCount the number of mouse clicks associated with the event
280 * @param popupTrigger a boolean value, <code>true</code> if this event is a trigger
281 * for a popup-menu
282 * @param scrollType the type of scrolling which should take place in
283 * response to this event; valid values are
284 * <code>WHEEL_UNIT_SCROLL</code> and
285 * <code>WHEEL_BLOCK_SCROLL</code>
286 * @param scrollAmount for scrollType <code>WHEEL_UNIT_SCROLL</code>,
287 * the number of units to be scrolled
288 * @param wheelRotation the integer number of "clicks" by which the mouse wheel
289 * was rotated
290 * @param preciseWheelRotation the double number of "clicks" by which the mouse wheel
291 * was rotated
292 *
293 * @throws IllegalArgumentException if <code>source</code> is null
294 * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, boolean)
295 * @see MouseEvent#MouseEvent(java.awt.Component, int, long, int, int, int, int, int, int, boolean, int)
296 * @since 1.7
297 */
298 public MouseWheelEvent (Component source, int id, long when, int modifiers,
299 int x, int y, int xAbs, int yAbs, int clickCount, boolean popupTrigger,
300 int scrollType, int scrollAmount, int wheelRotation, double preciseWheelRotation) {
301
302 super(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount,
303 popupTrigger, MouseEvent.NOBUTTON);
304
305 this.scrollType = scrollType;
306 this.scrollAmount = scrollAmount;
307 this.wheelRotation = wheelRotation;
308 this.preciseWheelRotation = preciseWheelRotation;
309
310 }
311
312 /**
313 * Returns the type of scrolling that should take place in response to this
314 * event. This is determined by the native platform. Legal values are:
315 * <ul>
316 * <li> MouseWheelEvent.WHEEL_UNIT_SCROLL
317 * <li> MouseWheelEvent.WHEEL_BLOCK_SCROLL
318 * </ul>
319 *
320 * @return either MouseWheelEvent.WHEEL_UNIT_SCROLL or
321 * MouseWheelEvent.WHEEL_BLOCK_SCROLL, depending on the configuration of
322 * the native platform.
323 * @see java.awt.Adjustable#getUnitIncrement
324 * @see java.awt.Adjustable#getBlockIncrement
325 * @see javax.swing.Scrollable#getScrollableUnitIncrement
326 * @see javax.swing.Scrollable#getScrollableBlockIncrement
327 */
328 public int getScrollType() {
329 return scrollType;
330 }
331
332 /**
333 * Returns the number of units that should be scrolled per
334 * click of mouse wheel rotation.
335 * Only valid if <code>getScrollType</code> returns
336 * <code>MouseWheelEvent.WHEEL_UNIT_SCROLL</code>
337 *
338 * @return number of units to scroll, or an undefined value if
339 * <code>getScrollType</code> returns
340 * <code>MouseWheelEvent.WHEEL_BLOCK_SCROLL</code>
341 * @see #getScrollType
342 */
343 public int getScrollAmount() {
344 return scrollAmount;
345 }
346
347 /**
348 * Returns the number of "clicks" the mouse wheel was rotated, as an integer.
349 * A partial rotation may occur if the mouse supports a high-resolution wheel.
350 * In this case, the method returns zero until a full "click" has been accumulated.
351 *
352 * @return negative values if the mouse wheel was rotated up/away from
353 * the user, and positive values if the mouse wheel was rotated down/
354 * towards the user
355 * @see #getPreciseWheelRotation
356 */
357 public int getWheelRotation() {
358 return wheelRotation;
359 }
360
361 /**
362 * Returns the number of "clicks" the mouse wheel was rotated, as a double.
363 * A partial rotation may occur if the mouse supports a high-resolution wheel.
364 * In this case, the return value will include a fractional "click".
365 *
366 * @return negative values if the mouse wheel was rotated up or away from
367 * the user, and positive values if the mouse wheel was rotated down or
368 * towards the user
369 * @see #getWheelRotation
370 * @since 1.7
371 */
372 public double getPreciseWheelRotation() {
373 return preciseWheelRotation;
374 }
375
376 /**
377 * This is a convenience method to aid in the implementation of
378 * the common-case MouseWheelListener - to scroll a ScrollPane or
379 * JScrollPane by an amount which conforms to the platform settings.
380 * (Note, however, that <code>ScrollPane</code> and
381 * <code>JScrollPane</code> already have this functionality built in.)
382 * <P>
383 * This method returns the number of units to scroll when scroll type is
384 * MouseWheelEvent.WHEEL_UNIT_SCROLL, and should only be called if
385 * <code>getScrollType</code> returns MouseWheelEvent.WHEEL_UNIT_SCROLL.
386 * <P>
387 * Direction of scroll, amount of wheel movement,
388 * and platform settings for wheel scrolling are all accounted for.
389 * This method does not and cannot take into account value of the
390 * Adjustable/Scrollable unit increment, as this will vary among
391 * scrolling components.
392 * <P>
393 * A simplified example of how this method might be used in a
394 * listener:
395 * <pre>
396 * mouseWheelMoved(MouseWheelEvent event) {
397 * ScrollPane sp = getScrollPaneFromSomewhere();
398 * Adjustable adj = sp.getVAdjustable()
399 * if (MouseWheelEvent.getScrollType() == WHEEL_UNIT_SCROLL) {
400 * int totalScrollAmount =
401 * event.getUnitsToScroll() *
402 * adj.getUnitIncrement();
403 * adj.setValue(adj.getValue() + totalScrollAmount);
404 * }
405 * }
406 * </pre>
407 *
408 * @return the number of units to scroll based on the direction and amount
409 * of mouse wheel rotation, and on the wheel scrolling settings of the
410 * native platform
411 * @see #getScrollType
412 * @see #getScrollAmount
413 * @see MouseWheelListener
414 * @see java.awt.Adjustable
415 * @see java.awt.Adjustable#getUnitIncrement
416 * @see javax.swing.Scrollable
417 * @see javax.swing.Scrollable#getScrollableUnitIncrement
418 * @see java.awt.ScrollPane
419 * @see java.awt.ScrollPane#setWheelScrollingEnabled
420 * @see javax.swing.JScrollPane
421 * @see javax.swing.JScrollPane#setWheelScrollingEnabled
422 */
423 public int getUnitsToScroll() {
424 return scrollAmount * wheelRotation;
425 }
426
427 /**
428 * Returns a parameter string identifying this event.
429 * This method is useful for event-logging and for debugging.
430 *
431 * @return a string identifying the event and its attributes
432 */
433 public String paramString() {
434 String scrollTypeStr = null;
435
436 if (getScrollType() == WHEEL_UNIT_SCROLL) {
437 scrollTypeStr = "WHEEL_UNIT_SCROLL";
438 }
439 else if (getScrollType() == WHEEL_BLOCK_SCROLL) {
440 scrollTypeStr = "WHEEL_BLOCK_SCROLL";
441 }
442 else {
443 scrollTypeStr = "unknown scroll type";
444 }
445 return super.paramString()+",scrollType="+scrollTypeStr+
446 ",scrollAmount="+getScrollAmount()+",wheelRotation="+
447 getWheelRotation()+",preciseWheelRotation="+getPreciseWheelRotation();
448 }
449 }