1/*
2 * Copyright (c) 1999, 2004, 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
26package sun.java2d.loops;
27
28public final class RenderCache {
29    final class Entry {
30        private SurfaceType src;
31        private CompositeType comp;
32        private SurfaceType dst;
33        private Object value;
34
35        public Entry(SurfaceType src,
36                     CompositeType comp,
37                     SurfaceType dst,
38                     Object value)
39        {
40            this.src = src;
41            this.comp = comp;
42            this.dst = dst;
43            this.value = value;
44        }
45
46        public boolean matches(SurfaceType src,
47                               CompositeType comp,
48                               SurfaceType dst)
49        {
50            // bug 4725045: using equals() causes different SurfaceType
51            // objects with the same strings to match in the cache, which is
52            // not the behavior we want.  Constrain the match to succeed only
53            // on object matches instead.
54            return ((this.src == src) &&
55                    (this.comp == comp) &&
56                    (this.dst == dst));
57        }
58
59        public Object getValue() {
60            return value;
61        }
62    }
63
64    private Entry entries[];
65
66    public RenderCache(int size) {
67        entries = new Entry[size];
68    }
69
70    public synchronized Object get(SurfaceType src,
71                      CompositeType comp,
72                      SurfaceType dst)
73    {
74        int max = entries.length - 1;
75        for (int i = max; i >= 0; i--) {
76            Entry e = entries[i];
77            if (e == null) {
78                break;
79            }
80            if (e.matches(src, comp, dst)) {
81                if (i < max - 4) {
82                    System.arraycopy(entries, i+1, entries, i, max - i);
83                    entries[max] = e;
84                }
85                return e.getValue();
86            }
87        }
88
89        return null;
90    }
91
92    public synchronized void put(SurfaceType src,
93                    CompositeType comp,
94                    SurfaceType dst,
95                    Object value)
96    {
97        Entry e = new Entry(src, comp, dst, value);
98
99        int num = entries.length;
100        System.arraycopy(entries, 1, entries, 0, num - 1);
101        entries[num - 1] = e;
102    }
103}
104