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// Copyright (c) 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "core/layout/HitTestCache.h"
#include "platform/Histogram.h"
#include "public/platform/Platform.h"
namespace blink {
bool HitTestCache::lookupCachedResult(HitTestResult& hitResult, uint64_t domTreeVersion)
{
bool result = false;
HitHistogramMetric metric = HitHistogramMetric::MISS;
if (hitResult.hitTestRequest().avoidCache()) {
metric = HitHistogramMetric::MISS_EXPLICIT_AVOID;
// For now we don't support rect based hit results.
} else if (domTreeVersion == m_domTreeVersion && !hitResult.hitTestLocation().isRectBasedTest()) {
for (const auto& cachedItem : m_items) {
if (cachedItem.hitTestLocation().point() == hitResult.hitTestLocation().point()) {
if (hitResult.hitTestRequest().equalForCacheability(cachedItem.hitTestRequest())) {
metric = HitHistogramMetric::HIT_EXACT_MATCH;
result = true;
hitResult = cachedItem;
break;
}
metric = HitHistogramMetric::MISS_VALIDITY_RECT_MATCHES;
}
}
}
DEFINE_STATIC_LOCAL(EnumerationHistogram, hitTestHistogram, ("Event.HitTest", static_cast<int32_t>(HitHistogramMetric::MAX_HIT_METRIC)));
hitTestHistogram.count(static_cast<int32_t>(metric));
return result;
}
void HitTestCache::addCachedResult(const HitTestResult& result, uint64_t domTreeVersion)
{
if (!result.isCacheable())
return;
// If the result was a hit test on an LayoutPart and the request allowed
// querying of the layout part; then the part hasn't been loaded yet.
if (result.isOverWidget() && result.hitTestRequest().allowsChildFrameContent())
return;
// For now don't support rect based or list based requests.
if (result.hitTestLocation().isRectBasedTest() || result.hitTestRequest().listBased())
return;
if (domTreeVersion != m_domTreeVersion)
clear();
if (m_items.size() < HIT_TEST_CACHE_SIZE)
m_items.resize(m_updateIndex + 1);
m_items.at(m_updateIndex).cacheValues(result);
m_domTreeVersion = domTreeVersion;
m_updateIndex++;
if (m_updateIndex >= HIT_TEST_CACHE_SIZE)
m_updateIndex = 0;
}
void HitTestCache::clear()
{
m_updateIndex = 0;
m_items.clear();
}
DEFINE_TRACE(HitTestCache)
{
visitor->trace(m_items);
}
} // namespace blink
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