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/*
* Copyright (C) 2013 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_FONT_DATA_CACHE_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_FONT_DATA_CACHE_H_
#include "third_party/blink/renderer/platform/fonts/font_platform_data.h"
#include "third_party/blink/renderer/platform/fonts/simple_font_data.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_hash_map.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_linked_hash_set.h"
namespace blink {
struct FontDataCacheKeyHashTraits : GenericHashTraits<const FontPlatformData*> {
STATIC_ONLY(FontDataCacheKeyHashTraits);
static unsigned GetHash(const FontPlatformData* platform_data) {
return platform_data->GetHash();
}
static bool Equal(const FontPlatformData* a, const FontPlatformData* b) {
return *a == *b;
}
static constexpr bool kSafeToCompareToEmptyOrDeleted = false;
};
class FontDataCache final {
DISALLOW_NEW();
public:
FontDataCache() = default;
FontDataCache(const FontDataCache&) = delete;
FontDataCache& operator=(const FontDataCache&) = delete;
void Trace(Visitor* visitor) const {
visitor->Trace(cache_);
visitor->Trace(strong_reference_lru_);
}
const SimpleFontData* Get(const FontPlatformData*,
bool subpixel_ascent_descent = false);
void Clear() {
cache_.clear();
strong_reference_lru_.clear();
}
private:
HeapHashMap<Member<const FontPlatformData>,
WeakMember<const SimpleFontData>,
FontDataCacheKeyHashTraits>
cache_;
// The above `cache_` is weak, meaning its entries will potentially be
// cleared if no other references exist.
// This LRU keeps a small (limited) number of strong references alive so they
// won't be cleared in the above cache for performance reasons.
HeapLinkedHashSet<Member<const SimpleFontData>> strong_reference_lru_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_FONT_DATA_CACHE_H_
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