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122 lines
4.0 KiB
Java
122 lines
4.0 KiB
Java
/*
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* Copyright (c) 2007, 2014, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.awt.image;
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import java.awt.image.BufferStrategy;
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import java.lang.ref.WeakReference;
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/**
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* Manages v-synced buffer strategies.
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*/
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public abstract class VSyncedBSManager {
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private static VSyncedBSManager theInstance;
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private static final boolean vSyncLimit =
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Boolean.valueOf(java.security.AccessController.doPrivileged(
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new sun.security.action.GetPropertyAction(
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"sun.java2d.vsynclimit", "true")));
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private static VSyncedBSManager getInstance(boolean create) {
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if (theInstance == null && create) {
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theInstance =
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vSyncLimit ? new SingleVSyncedBSMgr() : new NoLimitVSyncBSMgr();
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}
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return theInstance;
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}
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abstract boolean checkAllowed(BufferStrategy bs);
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abstract void relinquishVsync(BufferStrategy bs);
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/**
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* Returns true if the buffer strategy is allowed to be created
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* v-synced.
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*
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* @return true if the bs is allowed to be v-synced, false otherwise
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*/
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public static boolean vsyncAllowed(BufferStrategy bs) {
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VSyncedBSManager bsm = getInstance(true);
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return bsm.checkAllowed(bs);
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}
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/**
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* Lets the manager know that this buffer strategy is no longer interested
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* in being v-synced.
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*/
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public static synchronized void releaseVsync(BufferStrategy bs) {
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VSyncedBSManager bsm = getInstance(false);
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if (bsm != null) {
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bsm.relinquishVsync(bs);
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}
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}
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/**
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* An instance of the manager which allows any buffer strategy to be
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* v-synced.
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*/
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private static final class NoLimitVSyncBSMgr extends VSyncedBSManager {
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@Override
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boolean checkAllowed(BufferStrategy bs) {
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return true;
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}
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@Override
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void relinquishVsync(BufferStrategy bs) {
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}
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}
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/**
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* An instance of the manager which allows only one buffer strategy to
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* be v-synced at any give moment in the vm.
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*/
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private static final class SingleVSyncedBSMgr extends VSyncedBSManager {
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private WeakReference<BufferStrategy> strategy;
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@Override
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public synchronized boolean checkAllowed(BufferStrategy bs) {
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if (strategy != null) {
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BufferStrategy current = strategy.get();
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if (current != null) {
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return (current == bs);
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}
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}
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strategy = new WeakReference<BufferStrategy>(bs);
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return true;
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}
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@Override
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public synchronized void relinquishVsync(BufferStrategy bs) {
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if (strategy != null) {
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BufferStrategy b = strategy.get();
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if (b == bs) {
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strategy.clear();
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strategy = null;
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}
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}
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}
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}
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}
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