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/* * Copyright (c) 2007, 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.java2d; import sun.java2d.StateTrackable.State;import static sun.java2d.StateTrackable.State.*; /** * This class provides a basic pre-packaged implementation of the * complete {@link StateTrackable} interface with implementations * of the required methods in the interface and methods to manage * transitions in the state of the object. * Classes which wish to implement StateTrackable could create an * instance of this class and delegate all of their implementations * for {@code StateTrackable} methods to the corresponding methods * of this class. */public final class StateTrackableDelegate implements StateTrackable {    /**     * The {@code UNTRACKABLE_DELEGATE} provides an implementation     * of the StateTrackable interface that is permanently in the     * {@link State#UNTRACKABLE UNTRACKABLE} state.     */    public final static StateTrackableDelegate UNTRACKABLE_DELEGATE =        new StateTrackableDelegate(UNTRACKABLE);     /**     * The {@code IMMUTABLE_DELEGATE} provides an implementation     * of the StateTrackable interface that is permanently in the     * {@link State#IMMUTABLE IMMUTABLE} state.     */    public final static StateTrackableDelegate IMMUTABLE_DELEGATE =        new StateTrackableDelegate(IMMUTABLE);     /**     * Returns a {@code StateTrackableDelegate} instance with the     * specified initial {@link State State}.     * If the specified {@code State} is     * {@link State#UNTRACKABLE UNTRACKABLE} or     * {@link State#IMMUTABLE IMMUTABLE}     * then the approprirate static instance     * {@link #UNTRACKABLE_DELEGATE} or {@link #IMMUTABLE_DELEGATE}     * is returned.     */    public static StateTrackableDelegate createInstance(State state) {        switch (state) {        case UNTRACKABLE:            return UNTRACKABLE_DELEGATE;        case STABLE:            return new StateTrackableDelegate(STABLE);        case DYNAMIC:            return new StateTrackableDelegate(DYNAMIC);        case IMMUTABLE:            return IMMUTABLE_DELEGATE;        default:            throw new InternalError("unknown state");        }    }     private State theState;    StateTracker theTracker;   // package private for easy access from tracker    private int numDynamicAgents;     /**     * Constructs a StateTrackableDelegate object with the specified     * initial State.     */    private StateTrackableDelegate(State state) {        this.theState = state;    }     /**     * @inheritDoc     * @since 1.7     */    public State getState() {        return theState;    }     /**     * @inheritDoc     * @since 1.7     */    public synchronized StateTracker getStateTracker() {        StateTracker st = theTracker;        if (st == null) {            switch (theState) {            case IMMUTABLE:                st = StateTracker.ALWAYS_CURRENT;                break;            case STABLE:                st = new StateTracker() {                    public boolean isCurrent() {                        return (theTracker == this);                    }                };                break;            case DYNAMIC:                // We return the NEVER_CURRENT tracker, but that is                // just temporary while we are in the DYNAMIC state.                // NO BREAK            case UNTRACKABLE:                st = StateTracker.NEVER_CURRENT;                break;            }            theTracker = st;        }        return st;    }     /**     * This method provides an easy way for delegating classes to     * change the overall {@link State State} of the delegate to     * {@link State#IMMUTABLE IMMUTABLE}.     * @throws IllegalStateException if the current state is     *         {@link State#UNTRACKABLE UNTRACKABLE}     * @see #setUntrackable     * @since 1.7     */    public synchronized void setImmutable() {        if (theState == UNTRACKABLE || theState == DYNAMIC) {            throw new IllegalStateException("UNTRACKABLE or DYNAMIC "+                                            "objects cannot become IMMUTABLE");        }        theState = IMMUTABLE;        theTracker = null;    }     /**     * This method provides an easy way for delegating classes to     * change the overall {@link State State} of the delegate to     * {@link State#UNTRACKABLE UNTRACKABLE}.     * This method is typically called when references to the     * internal data buffers have been made public.     * @throws IllegalStateException if the current state is     *         {@link State#IMMUTABLE IMMUTABLE}     * @see #setImmutable     * @since 1.7     */    public synchronized void setUntrackable() {        if (theState == IMMUTABLE) {            throw new IllegalStateException("IMMUTABLE objects cannot "+                                            "become UNTRACKABLE");        }        theState = UNTRACKABLE;        theTracker = null;    }     /**     * This method provides an easy way for delegating classes to     * manage temporarily setting the overall {@link State State}     * of the delegate to {@link State#DYNAMIC DYNAMIC}     * during well-defined time frames of dynamic pixel updating.     * This method should be called once before each flow of control     * that might dynamically update the pixels in an uncontrolled     * or unpredictable fashion.     * <p>     * The companion method {@link #removeDynamicAgent} method should     * also be called once after each such flow of control has ended.     * Failing to call the remove method will result in this object     * permanently becoming {@link State#DYNAMIC DYNAMIC}     * and therefore effectively untrackable.     * <p>     * This method will only change the {@link State State} of the     * delegate if it is currently {@link State#STABLE STABLE}.     *     * @throws IllegalStateException if the current state is     *         {@link State#IMMUTABLE IMMUTABLE}     * @since 1.7     */    public synchronized void addDynamicAgent() {        if (theState == IMMUTABLE) {            throw new IllegalStateException("Cannot change state from "+                                            "IMMUTABLE");        }        ++numDynamicAgents;        if (theState == STABLE) {            theState = DYNAMIC;            theTracker = null;        }    }     /**     * This method provides an easy way for delegating classes to     * manage restoring the overall {@link State State} of the     * delegate back to {@link State#STABLE STABLE}     * after a well-defined time frame of dynamic pixel updating.     * This method should be called once after each flow of control     * that might dynamically update the pixels in an uncontrolled     * or unpredictable fashion has ended.     * <p>     * The companion method {@link #addDynamicAgent} method should     * have been called at some point before each such flow of     * control began.     * If this method is called without having previously called     * the add method, the {@link State State} of this object     * will become unreliable.     * <p>     * This method will only change the {@link State State} of the     * delegate if the number of outstanding dynamic agents has     * gone to 0 and it is currently     * {@link State#DYNAMIC DYNAMIC}.     *     * @since 1.7     */    protected synchronized void removeDynamicAgent() {        if (--numDynamicAgents == 0 && theState == DYNAMIC) {            theState = STABLE;            theTracker = null;        }    }     /**     * This method provides an easy way for delegating classes to     * indicate that the contents have changed.     * This method will invalidate outstanding StateTracker objects     * so that any other agents which maintain cached information     * about the pixels will know to refresh their cached copies.     * This method should be called after every modification to     * the data, such as any calls to any of the setElem methods.     * <p>     * Note that, for efficiency, this method does not check the     * {@link State State} of the object to see if it is compatible     * with being marked dirty     * (i.e. not {@link State#IMMUTABLE IMMUTABLE}).     * It is up to the callers to enforce the fact that an     * {@code IMMUTABLE} delegate is never modified.     * @since 1.7     */    public final void markDirty() {        theTracker = null;    }}