1 /* 2 * Copyright (c) 2007, 2014, 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 sun.awt.image; 27 28 import java.awt.image.BufferStrategy; 29 import java.lang.ref.WeakReference; 30 31 /** 32 * Manages v-synced buffer strategies. 33 */ 34 public abstract class VSyncedBSManager { 35 36 private static VSyncedBSManager theInstance; 37 38 private static final boolean vSyncLimit = 39 Boolean.valueOf(java.security.AccessController.doPrivileged( 40 new sun.security.action.GetPropertyAction( 41 "sun.java2d.vsynclimit", "true"))); 42 getInstance(boolean create)43 private static VSyncedBSManager getInstance(boolean create) { 44 if (theInstance == null && create) { 45 theInstance = 46 vSyncLimit ? new SingleVSyncedBSMgr() : new NoLimitVSyncBSMgr(); 47 } 48 return theInstance; 49 } 50 checkAllowed(BufferStrategy bs)51 abstract boolean checkAllowed(BufferStrategy bs); relinquishVsync(BufferStrategy bs)52 abstract void relinquishVsync(BufferStrategy bs); 53 54 /** 55 * Returns true if the buffer strategy is allowed to be created 56 * v-synced. 57 * 58 * @return true if the bs is allowed to be v-synced, false otherwise 59 */ vsyncAllowed(BufferStrategy bs)60 public static boolean vsyncAllowed(BufferStrategy bs) { 61 VSyncedBSManager bsm = getInstance(true); 62 return bsm.checkAllowed(bs); 63 } 64 65 /** 66 * Lets the manager know that this buffer strategy is no longer interested 67 * in being v-synced. 68 */ releaseVsync(BufferStrategy bs)69 public static synchronized void releaseVsync(BufferStrategy bs) { 70 VSyncedBSManager bsm = getInstance(false); 71 if (bsm != null) { 72 bsm.relinquishVsync(bs); 73 } 74 } 75 76 /** 77 * An instance of the manager which allows any buffer strategy to be 78 * v-synced. 79 */ 80 private static final class NoLimitVSyncBSMgr extends VSyncedBSManager { 81 @Override checkAllowed(BufferStrategy bs)82 boolean checkAllowed(BufferStrategy bs) { 83 return true; 84 } 85 86 @Override relinquishVsync(BufferStrategy bs)87 void relinquishVsync(BufferStrategy bs) { 88 } 89 } 90 91 /** 92 * An instance of the manager which allows only one buffer strategy to 93 * be v-synced at any give moment in the vm. 94 */ 95 private static final class SingleVSyncedBSMgr extends VSyncedBSManager { 96 private WeakReference<BufferStrategy> strategy; 97 98 @Override checkAllowed(BufferStrategy bs)99 public synchronized boolean checkAllowed(BufferStrategy bs) { 100 if (strategy != null) { 101 BufferStrategy current = strategy.get(); 102 if (current != null) { 103 return (current == bs); 104 } 105 } 106 strategy = new WeakReference<BufferStrategy>(bs); 107 return true; 108 } 109 110 @Override relinquishVsync(BufferStrategy bs)111 public synchronized void relinquishVsync(BufferStrategy bs) { 112 if (strategy != null) { 113 BufferStrategy b = strategy.get(); 114 if (b == bs) { 115 strategy.clear(); 116 strategy = null; 117 } 118 } 119 } 120 } 121 } 122