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      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 
     39 namespace blink {
     40 
     41 class SimpleFontData;
     42 
     43 struct 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 
     57 struct 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 
     75 class FontDataCache {
     76 public:
     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 
     89 private:
     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