--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/awt/ScrollPaneWheelScroller.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,187 @@
+/*
+ * Copyright 2000-2007 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 sun.awt;
+
+import java.awt.ScrollPane;
+import java.awt.Insets;
+import java.awt.Adjustable;
+import java.awt.event.MouseWheelEvent;
+
+import java.util.logging.*;
+
+/*
+ * ScrollPaneWheelScroller is a helper class for implmenenting mouse wheel
+ * scrolling on a java.awt.ScrollPane. It contains only static methods.
+ * No objects of this class may be instantiated, thus it is declared abstract.
+ */
+public abstract class ScrollPaneWheelScroller {
+
+ private static final Logger log = Logger.getLogger("sun.awt.ScrollPaneWheelScroller");
+
+ private ScrollPaneWheelScroller() {}
+
+ /*
+ * Called from ScrollPane.processMouseWheelEvent()
+ */
+ public static void handleWheelScrolling(ScrollPane sp, MouseWheelEvent e) {
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "x = " + e.getX() + ", y = " + e.getY() + ", src is " + e.getSource());
+ }
+ int increment = 0;
+
+ if (sp != null && e.getScrollAmount() != 0) {
+ Adjustable adj = getAdjustableToScroll(sp);
+ if (adj != null) {
+ increment = getIncrementFromAdjustable(adj, e);
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "increment from adjustable(" + adj.getClass() + ") : " + increment);
+ }
+ scrollAdjustable(adj, increment);
+ }
+ }
+ }
+
+ /*
+ * Given a ScrollPane, determine which Scrollbar should be scrolled by the
+ * mouse wheel, if any.
+ */
+ public static Adjustable getAdjustableToScroll(ScrollPane sp) {
+ int policy = sp.getScrollbarDisplayPolicy();
+
+ // if policy is display always or never, use vert
+ if (policy == ScrollPane.SCROLLBARS_ALWAYS ||
+ policy == ScrollPane.SCROLLBARS_NEVER) {
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "using vertical scrolling due to scrollbar policy");
+ }
+ return sp.getVAdjustable();
+
+ }
+ else {
+
+ Insets ins = sp.getInsets();
+ int vertScrollWidth = sp.getVScrollbarWidth();
+
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "insets: l = " + ins.left + ", r = " + ins.right +
+ ", t = " + ins.top + ", b = " + ins.bottom);
+ log.log(Level.FINER, "vertScrollWidth = " + vertScrollWidth);
+ }
+
+ // Check if scrollbar is showing by examining insets of the
+ // ScrollPane
+ if (ins.right >= vertScrollWidth) {
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "using vertical scrolling because scrollbar is present");
+ }
+ return sp.getVAdjustable();
+ }
+ else {
+ int horizScrollHeight = sp.getHScrollbarHeight();
+ if (ins.bottom >= horizScrollHeight) {
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "using horiz scrolling because scrollbar is present");
+ }
+ return sp.getHAdjustable();
+ }
+ else {
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "using NO scrollbar becsause neither is present");
+ }
+ return null;
+ }
+ }
+ }
+ }
+
+ /*
+ * Given the info in a MouseWheelEvent and an Adjustable to scroll, return
+ * the amount by which the Adjustable should be adjusted. This value may
+ * be positive or negative.
+ */
+ public static int getIncrementFromAdjustable(Adjustable adj,
+ MouseWheelEvent e) {
+ if (log.isLoggable(Level.FINE)) {
+ if (adj == null) {
+ log.log(Level.FINE, "Assertion (adj != null) failed");
+ }
+ }
+
+ int increment = 0;
+
+ if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
+ increment = e.getUnitsToScroll() * adj.getUnitIncrement();
+ }
+ else if (e.getScrollType() == MouseWheelEvent.WHEEL_BLOCK_SCROLL) {
+ increment = adj.getBlockIncrement() * e.getWheelRotation();
+ }
+ return increment;
+ }
+
+ /*
+ * Scroll the given Adjustable by the given amount. Checks the Adjustable's
+ * bounds and sets the new value to the Adjustable.
+ */
+ public static void scrollAdjustable(Adjustable adj, int amount) {
+ if (log.isLoggable(Level.FINE)) {
+ if (adj == null) {
+ log.log(Level.FINE, "Assertion (adj != null) failed");
+ }
+ if (amount == 0) {
+ log.log(Level.FINE, "Assertion (amount != 0) failed");
+ }
+ }
+
+ int current = adj.getValue();
+ int upperLimit = adj.getMaximum() - adj.getVisibleAmount();
+ if (log.isLoggable(Level.FINER)) {
+ log.log(Level.FINER, "doScrolling by " + amount);
+ }
+
+ if (amount > 0 && current < upperLimit) { // still some room to scroll
+ // down
+ if (current + amount < upperLimit) {
+ adj.setValue(current + amount);
+ return;
+ }
+ else {
+ adj.setValue(upperLimit);
+ return;
+ }
+ }
+ else if (amount < 0 && current > adj.getMinimum()) { // still some room
+ // to scroll up
+ if (current + amount > adj.getMinimum()) {
+ adj.setValue(current + amount);
+ return;
+ }
+ else {
+ adj.setValue(adj.getMinimum());
+ return;
+ }
+ }
+ }
+}