30 import java.awt.Adjustable;
31 import java.awt.event.MouseWheelEvent;
32
33 import sun.util.logging.PlatformLogger;
34
35 /*
36 * ScrollPaneWheelScroller is a helper class for implmenenting mouse wheel
37 * scrolling on a java.awt.ScrollPane. It contains only static methods.
38 * No objects of this class may be instantiated, thus it is declared abstract.
39 */
40 public abstract class ScrollPaneWheelScroller {
41
42 private static final PlatformLogger log = PlatformLogger.getLogger("sun.awt.ScrollPaneWheelScroller");
43
44 private ScrollPaneWheelScroller() {}
45
46 /*
47 * Called from ScrollPane.processMouseWheelEvent()
48 */
49 public static void handleWheelScrolling(ScrollPane sp, MouseWheelEvent e) {
50 if (log.isLoggable(PlatformLogger.FINER)) {
51 log.finer("x = " + e.getX() + ", y = " + e.getY() + ", src is " + e.getSource());
52 }
53 int increment = 0;
54
55 if (sp != null && e.getScrollAmount() != 0) {
56 Adjustable adj = getAdjustableToScroll(sp);
57 if (adj != null) {
58 increment = getIncrementFromAdjustable(adj, e);
59 if (log.isLoggable(PlatformLogger.FINER)) {
60 log.finer("increment from adjustable(" + adj.getClass() + ") : " + increment);
61 }
62 scrollAdjustable(adj, increment);
63 }
64 }
65 }
66
67 /*
68 * Given a ScrollPane, determine which Scrollbar should be scrolled by the
69 * mouse wheel, if any.
70 */
71 public static Adjustable getAdjustableToScroll(ScrollPane sp) {
72 int policy = sp.getScrollbarDisplayPolicy();
73
74 // if policy is display always or never, use vert
75 if (policy == ScrollPane.SCROLLBARS_ALWAYS ||
76 policy == ScrollPane.SCROLLBARS_NEVER) {
77 if (log.isLoggable(PlatformLogger.FINER)) {
78 log.finer("using vertical scrolling due to scrollbar policy");
79 }
80 return sp.getVAdjustable();
81
82 }
83 else {
84
85 Insets ins = sp.getInsets();
86 int vertScrollWidth = sp.getVScrollbarWidth();
87
88 if (log.isLoggable(PlatformLogger.FINER)) {
89 log.finer("insets: l = " + ins.left + ", r = " + ins.right +
90 ", t = " + ins.top + ", b = " + ins.bottom);
91 log.finer("vertScrollWidth = " + vertScrollWidth);
92 }
93
94 // Check if scrollbar is showing by examining insets of the
95 // ScrollPane
96 if (ins.right >= vertScrollWidth) {
97 if (log.isLoggable(PlatformLogger.FINER)) {
98 log.finer("using vertical scrolling because scrollbar is present");
99 }
100 return sp.getVAdjustable();
101 }
102 else {
103 int horizScrollHeight = sp.getHScrollbarHeight();
104 if (ins.bottom >= horizScrollHeight) {
105 if (log.isLoggable(PlatformLogger.FINER)) {
106 log.finer("using horiz scrolling because scrollbar is present");
107 }
108 return sp.getHAdjustable();
109 }
110 else {
111 if (log.isLoggable(PlatformLogger.FINER)) {
112 log.finer("using NO scrollbar becsause neither is present");
113 }
114 return null;
115 }
116 }
117 }
118 }
119
120 /*
121 * Given the info in a MouseWheelEvent and an Adjustable to scroll, return
122 * the amount by which the Adjustable should be adjusted. This value may
123 * be positive or negative.
124 */
125 public static int getIncrementFromAdjustable(Adjustable adj,
126 MouseWheelEvent e) {
127 if (log.isLoggable(PlatformLogger.FINE)) {
128 if (adj == null) {
129 log.fine("Assertion (adj != null) failed");
130 }
131 }
132
133 int increment = 0;
134
135 if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
136 increment = e.getUnitsToScroll() * adj.getUnitIncrement();
137 }
138 else if (e.getScrollType() == MouseWheelEvent.WHEEL_BLOCK_SCROLL) {
139 increment = adj.getBlockIncrement() * e.getWheelRotation();
140 }
141 return increment;
142 }
143
144 /*
145 * Scroll the given Adjustable by the given amount. Checks the Adjustable's
146 * bounds and sets the new value to the Adjustable.
147 */
148 public static void scrollAdjustable(Adjustable adj, int amount) {
149 if (log.isLoggable(PlatformLogger.FINE)) {
150 if (adj == null) {
151 log.fine("Assertion (adj != null) failed");
152 }
153 if (amount == 0) {
154 log.fine("Assertion (amount != 0) failed");
155 }
156 }
157
158 int current = adj.getValue();
159 int upperLimit = adj.getMaximum() - adj.getVisibleAmount();
160 if (log.isLoggable(PlatformLogger.FINER)) {
161 log.finer("doScrolling by " + amount);
162 }
163
164 if (amount > 0 && current < upperLimit) { // still some room to scroll
165 // down
166 if (current + amount < upperLimit) {
167 adj.setValue(current + amount);
168 return;
169 }
170 else {
171 adj.setValue(upperLimit);
172 return;
173 }
174 }
175 else if (amount < 0 && current > adj.getMinimum()) { // still some room
176 // to scroll up
177 if (current + amount > adj.getMinimum()) {
178 adj.setValue(current + amount);
179 return;
180 }
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30 import java.awt.Adjustable;
31 import java.awt.event.MouseWheelEvent;
32
33 import sun.util.logging.PlatformLogger;
34
35 /*
36 * ScrollPaneWheelScroller is a helper class for implmenenting mouse wheel
37 * scrolling on a java.awt.ScrollPane. It contains only static methods.
38 * No objects of this class may be instantiated, thus it is declared abstract.
39 */
40 public abstract class ScrollPaneWheelScroller {
41
42 private static final PlatformLogger log = PlatformLogger.getLogger("sun.awt.ScrollPaneWheelScroller");
43
44 private ScrollPaneWheelScroller() {}
45
46 /*
47 * Called from ScrollPane.processMouseWheelEvent()
48 */
49 public static void handleWheelScrolling(ScrollPane sp, MouseWheelEvent e) {
50 if (log.isLoggable(PlatformLogger.Level.FINER)) {
51 log.finer("x = " + e.getX() + ", y = " + e.getY() + ", src is " + e.getSource());
52 }
53 int increment = 0;
54
55 if (sp != null && e.getScrollAmount() != 0) {
56 Adjustable adj = getAdjustableToScroll(sp);
57 if (adj != null) {
58 increment = getIncrementFromAdjustable(adj, e);
59 if (log.isLoggable(PlatformLogger.Level.FINER)) {
60 log.finer("increment from adjustable(" + adj.getClass() + ") : " + increment);
61 }
62 scrollAdjustable(adj, increment);
63 }
64 }
65 }
66
67 /*
68 * Given a ScrollPane, determine which Scrollbar should be scrolled by the
69 * mouse wheel, if any.
70 */
71 public static Adjustable getAdjustableToScroll(ScrollPane sp) {
72 int policy = sp.getScrollbarDisplayPolicy();
73
74 // if policy is display always or never, use vert
75 if (policy == ScrollPane.SCROLLBARS_ALWAYS ||
76 policy == ScrollPane.SCROLLBARS_NEVER) {
77 if (log.isLoggable(PlatformLogger.Level.FINER)) {
78 log.finer("using vertical scrolling due to scrollbar policy");
79 }
80 return sp.getVAdjustable();
81
82 }
83 else {
84
85 Insets ins = sp.getInsets();
86 int vertScrollWidth = sp.getVScrollbarWidth();
87
88 if (log.isLoggable(PlatformLogger.Level.FINER)) {
89 log.finer("insets: l = " + ins.left + ", r = " + ins.right +
90 ", t = " + ins.top + ", b = " + ins.bottom);
91 log.finer("vertScrollWidth = " + vertScrollWidth);
92 }
93
94 // Check if scrollbar is showing by examining insets of the
95 // ScrollPane
96 if (ins.right >= vertScrollWidth) {
97 if (log.isLoggable(PlatformLogger.Level.FINER)) {
98 log.finer("using vertical scrolling because scrollbar is present");
99 }
100 return sp.getVAdjustable();
101 }
102 else {
103 int horizScrollHeight = sp.getHScrollbarHeight();
104 if (ins.bottom >= horizScrollHeight) {
105 if (log.isLoggable(PlatformLogger.Level.FINER)) {
106 log.finer("using horiz scrolling because scrollbar is present");
107 }
108 return sp.getHAdjustable();
109 }
110 else {
111 if (log.isLoggable(PlatformLogger.Level.FINER)) {
112 log.finer("using NO scrollbar becsause neither is present");
113 }
114 return null;
115 }
116 }
117 }
118 }
119
120 /*
121 * Given the info in a MouseWheelEvent and an Adjustable to scroll, return
122 * the amount by which the Adjustable should be adjusted. This value may
123 * be positive or negative.
124 */
125 public static int getIncrementFromAdjustable(Adjustable adj,
126 MouseWheelEvent e) {
127 if (log.isLoggable(PlatformLogger.Level.FINE)) {
128 if (adj == null) {
129 log.fine("Assertion (adj != null) failed");
130 }
131 }
132
133 int increment = 0;
134
135 if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
136 increment = e.getUnitsToScroll() * adj.getUnitIncrement();
137 }
138 else if (e.getScrollType() == MouseWheelEvent.WHEEL_BLOCK_SCROLL) {
139 increment = adj.getBlockIncrement() * e.getWheelRotation();
140 }
141 return increment;
142 }
143
144 /*
145 * Scroll the given Adjustable by the given amount. Checks the Adjustable's
146 * bounds and sets the new value to the Adjustable.
147 */
148 public static void scrollAdjustable(Adjustable adj, int amount) {
149 if (log.isLoggable(PlatformLogger.Level.FINE)) {
150 if (adj == null) {
151 log.fine("Assertion (adj != null) failed");
152 }
153 if (amount == 0) {
154 log.fine("Assertion (amount != 0) failed");
155 }
156 }
157
158 int current = adj.getValue();
159 int upperLimit = adj.getMaximum() - adj.getVisibleAmount();
160 if (log.isLoggable(PlatformLogger.Level.FINER)) {
161 log.finer("doScrolling by " + amount);
162 }
163
164 if (amount > 0 && current < upperLimit) { // still some room to scroll
165 // down
166 if (current + amount < upperLimit) {
167 adj.setValue(current + amount);
168 return;
169 }
170 else {
171 adj.setValue(upperLimit);
172 return;
173 }
174 }
175 else if (amount < 0 && current > adj.getMinimum()) { // still some room
176 // to scroll up
177 if (current + amount > adj.getMinimum()) {
178 adj.setValue(current + amount);
179 return;
180 }
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