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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 "third_party/blink/renderer/core/layout/hit_test_cache.h"
#include "third_party/blink/public/platform/platform.h"
#include "third_party/blink/renderer/platform/instrumentation/histogram.h"
namespace blink {
bool HitTestCache::LookupCachedResult(const HitTestLocation& location,
HitTestResult& hit_result,
uint64_t dom_tree_version) {
bool result = false;
HitHistogramMetric metric = HitHistogramMetric::MISS;
if (hit_result.GetHitTestRequest().AvoidCache()) {
metric = HitHistogramMetric::MISS_EXPLICIT_AVOID;
// For now we don't support rect based hit results.
} else if (dom_tree_version == dom_tree_version_ &&
!location.IsRectBasedTest()) {
for (const auto& cached_item : items_) {
if (cached_item.location.Point() == location.Point()) {
if (hit_result.GetHitTestRequest().EqualForCacheability(
cached_item.result.GetHitTestRequest())) {
metric = HitHistogramMetric::HIT_EXACT_MATCH;
result = true;
hit_result = cached_item.result;
break;
}
metric = HitHistogramMetric::MISS_VALIDITY_RECT_MATCHES;
}
}
}
DEFINE_STATIC_LOCAL(
EnumerationHistogram, hit_test_histogram,
("Event.HitTest",
static_cast<int32_t>(HitHistogramMetric::MAX_HIT_METRIC)));
hit_test_histogram.Count(static_cast<int32_t>(metric));
return result;
}
void HitTestCacheEntry::Trace(Visitor* visitor) {
visitor->Trace(result);
}
void HitTestCacheEntry::CacheValues(const HitTestCacheEntry& other) {
*this = other;
result.CacheValues(other.result);
}
void HitTestCache::AddCachedResult(const HitTestLocation& location,
const HitTestResult& result,
uint64_t dom_tree_version) {
if (!result.IsCacheable())
return;
// If the result was a hit test on an LayoutEmbeddedContent and the request
// allowed querying of the layout part; then the part hasn't been loaded yet.
if (result.IsOverEmbeddedContentView() &&
result.GetHitTestRequest().AllowsChildFrameContent())
return;
// For now don't support rect based or list based requests.
if (location.IsRectBasedTest() || result.GetHitTestRequest().ListBased())
return;
if (dom_tree_version != dom_tree_version_)
Clear();
if (items_.size() < HIT_TEST_CACHE_SIZE)
items_.resize(update_index_ + 1);
HitTestCacheEntry cache_entry;
cache_entry.location = location;
cache_entry.result = result;
items_.at(update_index_).CacheValues(cache_entry);
dom_tree_version_ = dom_tree_version;
update_index_++;
if (update_index_ >= HIT_TEST_CACHE_SIZE)
update_index_ = 0;
}
void HitTestCache::Clear() {
update_index_ = 0;
items_.clear();
}
void HitTestCache::Trace(Visitor* visitor) {
visitor->Trace(items_);
}
} // namespace blink
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