1 /*
2 * Copyright (c) 2007, 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.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 void markDirty() {
254 theTracker = null;
255 }
256 }