third_party/WebKit/Source/core/layout/HitTestCache.cpp

   1 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "config.h"
   6 #include "core/layout/HitTestCache.h"
   7
   8 #include "public/platform/Platform.h"
   9
  10 namespace blink {
  11
  12 bool HitTestCache::lookupCachedResult(HitTestResult& hitResult, uint64_t domTreeVersion)
  13 {
  14     bool result = false;
  15     HitHistogramMetric metric = HitHistogramMetric::MISS;
  16     if (hitResult.hitTestRequest().avoidCache()) {
  17         metric = HitHistogramMetric::MISS_EXPLICIT_AVOID;
  18     // For now we don't support rect based hit results.
  19     } else if (domTreeVersion == m_domTreeVersion && !hitResult.hitTestLocation().isRectBasedTest()) {
  20         for (const auto& cachedItem : m_items) {
  21             if (cachedItem.hitTestLocation().point() == hitResult.hitTestLocation().point()) {
  22                 if (hitResult.hitTestRequest().equalForCacheability(cachedItem.hitTestRequest())) {
  23                     metric = HitHistogramMetric::HIT_EXACT_MATCH;
  24                     result = true;
  25                     hitResult = cachedItem;
  26                     break;
  27                 }
  28                 metric = HitHistogramMetric::MISS_VALIDITY_RECT_MATCHES;
  29             }
  30         }
  31     }
  32     Platform::current()->histogramEnumeration("Event.HitTest", static_cast<int>(metric), static_cast<int>(HitHistogramMetric::MAX_HIT_METRIC));
  33     return result;
  34 }
  35
  36 void HitTestCache::addCachedResult(const HitTestResult& result, uint64_t domTreeVersion)
  37 {
  38     if (!result.isCacheable())
  39         return;
  40
  41     // If the result was a hit test on an LayoutPart and the request allowed
  42     // querying of the layout part; then the part hasn't been loaded yet.
  43     if (result.isOverWidget() && result.hitTestRequest().allowsChildFrameContent())
  44         return;
  45
  46     // For now don't support rect based or list based requests.
  47     if (result.hitTestLocation().isRectBasedTest() || result.hitTestRequest().listBased())
  48         return;
  49     if (domTreeVersion != m_domTreeVersion)
  50         clear();
  51     if (m_items.size() < HIT_TEST_CACHE_SIZE)
  52         m_items.resize(m_updateIndex + 1);
  53
  54     m_items.at(m_updateIndex).cacheValues(result);
  55     m_domTreeVersion = domTreeVersion;
  56
  57     m_updateIndex++;
  58     if (m_updateIndex >= HIT_TEST_CACHE_SIZE)
  59         m_updateIndex = 0;
  60 }
  61
  62 void HitTestCache::clear()
  63 {
  64     m_updateIndex = 0;
  65     m_items.clear();
  66 }
  67
  68 DEFINE_TRACE(HitTestCache)
  69 {
  70     visitor->trace(m_items);
  71 }
  72
  73 } // namespace blink