| /* |
| * Copyright (c) 2000, 2013, Oracle and/or its affiliates. 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.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 sun.util.logging.PlatformLogger; |
| |
| /* |
| * 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 PlatformLogger log = PlatformLogger.getLogger("sun.awt.ScrollPaneWheelScroller"); |
| |
| private ScrollPaneWheelScroller() {} |
| |
| /* |
| * Called from ScrollPane.processMouseWheelEvent() |
| */ |
| public static void handleWheelScrolling(ScrollPane sp, MouseWheelEvent e) { |
| if (log.isLoggable(PlatformLogger.Level.FINER)) { |
| log.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(PlatformLogger.Level.FINER)) { |
| log.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(PlatformLogger.Level.FINER)) { |
| log.finer("using vertical scrolling due to scrollbar policy"); |
| } |
| return sp.getVAdjustable(); |
| |
| } |
| else { |
| |
| Insets ins = sp.getInsets(); |
| int vertScrollWidth = sp.getVScrollbarWidth(); |
| |
| if (log.isLoggable(PlatformLogger.Level.FINER)) { |
| log.finer("insets: l = " + ins.left + ", r = " + ins.right + |
| ", t = " + ins.top + ", b = " + ins.bottom); |
| log.finer("vertScrollWidth = " + vertScrollWidth); |
| } |
| |
| // Check if scrollbar is showing by examining insets of the |
| // ScrollPane |
| if (ins.right >= vertScrollWidth) { |
| if (log.isLoggable(PlatformLogger.Level.FINER)) { |
| log.finer("using vertical scrolling because scrollbar is present"); |
| } |
| return sp.getVAdjustable(); |
| } |
| else { |
| int horizScrollHeight = sp.getHScrollbarHeight(); |
| if (ins.bottom >= horizScrollHeight) { |
| if (log.isLoggable(PlatformLogger.Level.FINER)) { |
| log.finer("using horiz scrolling because scrollbar is present"); |
| } |
| return sp.getHAdjustable(); |
| } |
| else { |
| if (log.isLoggable(PlatformLogger.Level.FINER)) { |
| log.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(PlatformLogger.Level.FINE)) { |
| if (adj == null) { |
| log.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(PlatformLogger.Level.FINE)) { |
| if (adj == null) { |
| log.fine("Assertion (adj != null) failed"); |
| } |
| if (amount == 0) { |
| log.fine("Assertion (amount != 0) failed"); |
| } |
| } |
| |
| int current = adj.getValue(); |
| int upperLimit = adj.getMaximum() - adj.getVisibleAmount(); |
| if (log.isLoggable(PlatformLogger.Level.FINER)) { |
| log.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; |
| } |
| } |
| } |
| } |