J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2007 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package sun.java2d; |
| 27 | |
| 28 | import sun.java2d.StateTrackable.State; |
| 29 | import static sun.java2d.StateTrackable.State.*; |
| 30 | |
| 31 | /** |
| 32 | * This class provides a basic pre-packaged implementation of the |
| 33 | * complete {@link StateTrackable} interface with implementations |
| 34 | * of the required methods in the interface and methods to manage |
| 35 | * transitions in the state of the object. |
| 36 | * Classes which wish to implement StateTrackable could create an |
| 37 | * instance of this class and delegate all of their implementations |
| 38 | * for {@code StateTrackable} methods to the corresponding methods |
| 39 | * of this class. |
| 40 | */ |
| 41 | public final class StateTrackableDelegate implements StateTrackable { |
| 42 | /** |
| 43 | * The {@code UNTRACKABLE_DELEGATE} provides an implementation |
| 44 | * of the StateTrackable interface that is permanently in the |
| 45 | * {@link State#UNTRACKABLE UNTRACKABLE} state. |
| 46 | */ |
| 47 | public final static StateTrackableDelegate UNTRACKABLE_DELEGATE = |
| 48 | new StateTrackableDelegate(UNTRACKABLE); |
| 49 | |
| 50 | /** |
| 51 | * The {@code IMMUTABLE_DELEGATE} provides an implementation |
| 52 | * of the StateTrackable interface that is permanently in the |
| 53 | * {@link State#IMMUTABLE IMMUTABLE} state. |
| 54 | */ |
| 55 | public final static StateTrackableDelegate IMMUTABLE_DELEGATE = |
| 56 | new StateTrackableDelegate(IMMUTABLE); |
| 57 | |
| 58 | /** |
| 59 | * Returns a {@code StateTrackableDelegate} instance with the |
| 60 | * specified initial {@link State State}. |
| 61 | * If the specified {@code State} is |
| 62 | * {@link State#UNTRACKABLE UNTRACKABLE} or |
| 63 | * {@link State#IMMUTABLE IMMUTABLE} |
| 64 | * then the approprirate static instance |
| 65 | * {@link #UNTRACKABLE_DELEGATE} or {@link #IMMUTABLE_DELEGATE} |
| 66 | * is returned. |
| 67 | */ |
| 68 | public static StateTrackableDelegate createInstance(State state) { |
| 69 | switch (state) { |
| 70 | case UNTRACKABLE: |
| 71 | return UNTRACKABLE_DELEGATE; |
| 72 | case STABLE: |
| 73 | return new StateTrackableDelegate(STABLE); |
| 74 | case DYNAMIC: |
| 75 | return new StateTrackableDelegate(DYNAMIC); |
| 76 | case IMMUTABLE: |
| 77 | return IMMUTABLE_DELEGATE; |
| 78 | default: |
| 79 | throw new InternalError("unknown state"); |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | private State theState; |
| 84 | StateTracker theTracker; // package private for easy access from tracker |
| 85 | private int numDynamicAgents; |
| 86 | |
| 87 | /** |
| 88 | * Constructs a StateTrackableDelegate object with the specified |
| 89 | * initial State. |
| 90 | */ |
| 91 | private StateTrackableDelegate(State state) { |
| 92 | this.theState = state; |
| 93 | } |
| 94 | |
| 95 | /** |
| 96 | * @inheritDoc |
| 97 | * @since 1.7 |
| 98 | */ |
| 99 | public State getState() { |
| 100 | return theState; |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * @inheritDoc |
| 105 | * @since 1.7 |
| 106 | */ |
| 107 | public synchronized StateTracker getStateTracker() { |
| 108 | StateTracker st = theTracker; |
| 109 | if (st == null) { |
| 110 | switch (theState) { |
| 111 | case IMMUTABLE: |
| 112 | st = StateTracker.ALWAYS_CURRENT; |
| 113 | break; |
| 114 | case STABLE: |
| 115 | st = new StateTracker() { |
| 116 | public boolean isCurrent() { |
| 117 | return (theTracker == this); |
| 118 | } |
| 119 | }; |
| 120 | break; |
| 121 | case DYNAMIC: |
| 122 | // We return the NEVER_CURRENT tracker, but that is |
| 123 | // just temporary while we are in the DYNAMIC state. |
| 124 | // NO BREAK |
| 125 | case UNTRACKABLE: |
| 126 | st = StateTracker.NEVER_CURRENT; |
| 127 | break; |
| 128 | } |
| 129 | theTracker = st; |
| 130 | } |
| 131 | return st; |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * This method provides an easy way for delegating classes to |
| 136 | * change the overall {@link State State} of the delegate to |
| 137 | * {@link State#IMMUTABLE IMMUTABLE}. |
| 138 | * @throws IllegalStateException if the current state is |
| 139 | * {@link State#UNTRACKABLE UNTRACKABLE} |
| 140 | * @see #setUntrackable |
| 141 | * @since 1.7 |
| 142 | */ |
| 143 | public synchronized void setImmutable() { |
| 144 | if (theState == UNTRACKABLE || theState == DYNAMIC) { |
| 145 | throw new IllegalStateException("UNTRACKABLE or DYNAMIC "+ |
| 146 | "objects cannot become IMMUTABLE"); |
| 147 | } |
| 148 | theState = IMMUTABLE; |
| 149 | theTracker = null; |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * This method provides an easy way for delegating classes to |
| 154 | * change the overall {@link State State} of the delegate to |
| 155 | * {@link State#UNTRACKABLE UNTRACKABLE}. |
| 156 | * This method is typically called when references to the |
| 157 | * internal data buffers have been made public. |
| 158 | * @throws IllegalStateException if the current state is |
| 159 | * {@link State#IMMUTABLE IMMUTABLE} |
| 160 | * @see #setImmutable |
| 161 | * @since 1.7 |
| 162 | */ |
| 163 | public synchronized void setUntrackable() { |
| 164 | if (theState == IMMUTABLE) { |
| 165 | throw new IllegalStateException("IMMUTABLE objects cannot "+ |
| 166 | "become UNTRACKABLE"); |
| 167 | } |
| 168 | theState = UNTRACKABLE; |
| 169 | theTracker = null; |
| 170 | } |
| 171 | |
| 172 | /** |
| 173 | * This method provides an easy way for delegating classes to |
| 174 | * manage temporarily setting the overall {@link State State} |
| 175 | * of the delegate to {@link State#DYNAMIC DYNAMIC} |
| 176 | * during well-defined time frames of dynamic pixel updating. |
| 177 | * This method should be called once before each flow of control |
| 178 | * that might dynamically update the pixels in an uncontrolled |
| 179 | * or unpredictable fashion. |
| 180 | * <p> |
| 181 | * The companion method {@link #removeDynamicAgent} method should |
| 182 | * also be called once after each such flow of control has ended. |
| 183 | * Failing to call the remove method will result in this object |
| 184 | * permanently becoming {@link State#DYNAMIC DYNAMIC} |
| 185 | * and therefore effectively untrackable. |
| 186 | * <p> |
| 187 | * This method will only change the {@link State State} of the |
| 188 | * delegate if it is currently {@link State#STABLE STABLE}. |
| 189 | * |
| 190 | * @throws IllegalStateException if the current state is |
| 191 | * {@link State#IMMUTABLE IMMUTABLE} |
| 192 | * @since 1.7 |
| 193 | */ |
| 194 | public synchronized void addDynamicAgent() { |
| 195 | if (theState == IMMUTABLE) { |
| 196 | throw new IllegalStateException("Cannot change state from "+ |
| 197 | "IMMUTABLE"); |
| 198 | } |
| 199 | ++numDynamicAgents; |
| 200 | if (theState == STABLE) { |
| 201 | theState = DYNAMIC; |
| 202 | theTracker = null; |
| 203 | } |
| 204 | } |
| 205 | |
| 206 | /** |
| 207 | * This method provides an easy way for delegating classes to |
| 208 | * manage restoring the overall {@link State State} of the |
| 209 | * delegate back to {@link State#STABLE STABLE} |
| 210 | * after a well-defined time frame of dynamic pixel updating. |
| 211 | * This method should be called once after each flow of control |
| 212 | * that might dynamically update the pixels in an uncontrolled |
| 213 | * or unpredictable fashion has ended. |
| 214 | * <p> |
| 215 | * The companion method {@link #addDynamicAgent} method should |
| 216 | * have been called at some point before each such flow of |
| 217 | * control began. |
| 218 | * If this method is called without having previously called |
| 219 | * the add method, the {@link State State} of this object |
| 220 | * will become unreliable. |
| 221 | * <p> |
| 222 | * This method will only change the {@link State State} of the |
| 223 | * delegate if the number of outstanding dynamic agents has |
| 224 | * gone to 0 and it is currently |
| 225 | * {@link State#DYNAMIC DYNAMIC}. |
| 226 | * |
| 227 | * @since 1.7 |
| 228 | */ |
| 229 | protected synchronized void removeDynamicAgent() { |
| 230 | if (--numDynamicAgents == 0 && theState == DYNAMIC) { |
| 231 | theState = STABLE; |
| 232 | theTracker = null; |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | /** |
| 237 | * This method provides an easy way for delegating classes to |
| 238 | * indicate that the contents have changed. |
| 239 | * This method will invalidate outstanding StateTracker objects |
| 240 | * so that any other agents which maintain cached information |
| 241 | * about the pixels will know to refresh their cached copies. |
| 242 | * This method should be called after every modification to |
| 243 | * the data, such as any calls to any of the setElem methods. |
| 244 | * <p> |
| 245 | * Note that, for efficiency, this method does not check the |
| 246 | * {@link State State} of the object to see if it is compatible |
| 247 | * with being marked dirty |
| 248 | * (i.e. not {@link State#IMMUTABLE IMMUTABLE}). |
| 249 | * It is up to the callers to enforce the fact that an |
| 250 | * {@code IMMUTABLE} delegate is never modified. |
| 251 | * @since 1.7 |
| 252 | */ |
| 253 | public final void markDirty() { |
| 254 | theTracker = null; |
| 255 | } |
| 256 | } |