1/*
2 * Copyright (C) 2013 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef FontDataCache_h
32#define FontDataCache_h
33
34#include "platform/fonts/FontCache.h"
35#include "platform/fonts/FontPlatformData.h"
36#include "wtf/HashMap.h"
37#include "wtf/ListHashSet.h"
38
39namespace blink {
40
41class SimpleFontData;
42
43struct FontDataCacheKeyHash {
44    static unsigned hash(const FontPlatformData& platformData)
45    {
46        return platformData.hash();
47    }
48
49    static bool equal(const FontPlatformData& a, const FontPlatformData& b)
50    {
51        return a == b;
52    }
53
54    static const bool safeToCompareToEmptyOrDeleted = true;
55};
56
57struct FontDataCacheKeyTraits : WTF::GenericHashTraits<FontPlatformData> {
58    static const bool emptyValueIsZero = true;
59    static const bool needsDestruction = true;
60    static const FontPlatformData& emptyValue()
61    {
62        DEFINE_STATIC_LOCAL(FontPlatformData, key, (0.f, false, false));
63        return key;
64    }
65    static void constructDeletedValue(FontPlatformData& slot, bool)
66    {
67        new (NotNull, &slot) FontPlatformData(WTF::HashTableDeletedValue);
68    }
69    static bool isDeletedValue(const FontPlatformData& value)
70    {
71        return value.isHashTableDeletedValue();
72    }
73};
74
75class FontDataCache {
76public:
77    PassRefPtr<SimpleFontData> get(const FontPlatformData*, ShouldRetain = Retain);
78    bool contains(const FontPlatformData*) const;
79    void release(const SimpleFontData*);
80
81    // This is used by FontVerticalDataCache to mark all items with vertical data
82    // that are currently in cache as "in cache", which is later used to sweep the FontVerticalDataCache.
83    void markAllVerticalData();
84
85    // Purges items in FontDataCache according to provided severity.
86    // Returns true if any removal of cache items actually occurred.
87    bool purge(PurgeSeverity);
88
89private:
90    bool purgeLeastRecentlyUsed(int count);
91
92    typedef HashMap<FontPlatformData, pair<RefPtr<SimpleFontData>, unsigned>, FontDataCacheKeyHash, FontDataCacheKeyTraits> Cache;
93    Cache m_cache;
94    ListHashSet<RefPtr<SimpleFontData> > m_inactiveFontData;
95};
96
97} // namespace blink
98
99#endif
100