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Side by Side Diff: Source/core/layout/HitTestCache.h

Issue 1186843003: Revert "Oilpan: fix build after r197063, move HitTestCache to the heap." (Closed) Base URL: https://chromium.googlesource.com/chromium/blink.git@master
Patch Set: Created 5 years, 6 months ago
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1 // Copyright (c) 2015 The Chromium Authors. All rights reserved. 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 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #ifndef HitTestCache_h 5 #ifndef HitTestCache_h
6 #define HitTestCache_h 6 #define HitTestCache_h
7 7
8 #include "core/layout/HitTestResult.h" 8 #include "core/layout/HitTestResult.h"
9 #include "platform/heap/Handle.h"
10 #include "wtf/Vector.h" 9 #include "wtf/Vector.h"
11 10
12 namespace blink { 11 namespace blink {
13 12
14 // This object implements a cache for storing successful hit tests to DOM nodes 13 // This object implements a cache for storing successful hit tests to DOM nodes
15 // in the visible viewport. The cache is cleared on dom modifications, 14 // in the visible viewport. The cache is cleared on dom modifications,
16 // scrolling, CSS style modifications. 15 // scrolling, CSS style modifications.
17 // 16 //
18 // Multiple hit tests can occur when processing events. Typically the DOM doesn' t 17 // Multiple hit tests can occur when processing events. Typically the DOM doesn' t
19 // change when each event is processed so in order to decrease the time spent 18 // change when each event is processed so in order to decrease the time spent
20 // processing the events a hit cache is useful. For example a GestureTap event 19 // processing the events a hit cache is useful. For example a GestureTap event
21 // will generate a series of simulated mouse events (move, down, up, click) 20 // will generate a series of simulated mouse events (move, down, up, click)
22 // with the same co-ordinates and ideally we'd like to do the hit test once 21 // with the same co-ordinates and ideally we'd like to do the hit test once
23 // and use the result for the targetting of each event. 22 // and use the result for the targetting of each event.
24 // 23 //
25 // Some of the related design, motivation can be found in: 24 // Some of the related design, motivation can be found in:
26 // https://docs.google.com/document/d/1b0NYAD4S9BJIpHGa4JD2HLmW28f2rUh1jlqrgpU3z VU/ 25 // https://docs.google.com/document/d/1b0NYAD4S9BJIpHGa4JD2HLmW28f2rUh1jlqrgpU3z VU/
27 // 26 //
28 27
29 // A cache size of 2 is used because it is relatively cheap to store; 28 // A cache size of 2 is used because it is relatively cheap to store;
30 // and the ping-pong behaviour of some of the HitTestRequest flags during 29 // and the ping-pong behaviour of some of the HitTestRequest flags during
31 // Mouse/Touch/Pointer events can generate increased cache misses with 30 // Mouse/Touch/Pointer events can generate increased cache misses with
32 // size of 1. 31 // size of 1.
33 #define HIT_TEST_CACHE_SIZE (2) 32 #define HIT_TEST_CACHE_SIZE (2)
34 33
35 class HitTestCache final : public NoBaseWillBeGarbageCollectedFinalized<HitTestC ache> { 34 class HitTestCache {
36 public: 35 public:
37 static PassOwnPtrWillBeRawPtr<HitTestCache> create() 36 HitTestCache() = default;
38 {
39 return adoptPtrWillBeNoop(new HitTestCache);
40 }
41 37
42 // Check the cache for a possible hit and update |result| if 38 // Check the cache for a possible hit and update |result| if
43 // hit encountered; returning true. Otherwise false. 39 // hit encountered; returning true. Otherwise false.
44 bool lookupCachedResult(HitTestResult&, uint64_t domTreeVersion); 40 bool lookupCachedResult(HitTestResult&, uint64_t domTreeVersion);
45 41
46 void clear(); 42 void clear();
47 43
48 // Verify that the |actual| object matches the |expected| object; and 44 // Verify that the |actual| object matches the |expected| object; and
49 // log UMA metrics indicating the result. 45 // log UMA metrics indicating the result.
50 static void verifyCachedResult(const HitTestResult& expected, const HitTestR esult& actual); 46 static void verifyCachedResult(const HitTestResult& expected, const HitTestR esult& actual);
51 47
52 // Adds a HitTestResult to the cache. 48 // Adds a HitTestResult to the cache.
53 void addCachedResult(const HitTestResult&, uint64_t domTreeVersion); 49 void addCachedResult(const HitTestResult&, uint64_t domTreeVersion);
54 50
55 DECLARE_TRACE();
56
57 private: 51 private:
58 HitTestCache() = default;
59
60 // These values are reported in UMA as the "EventHitTest" enumeration. 52 // These values are reported in UMA as the "EventHitTest" enumeration.
61 // Do not reorder, append new values at the end, deprecate old 53 // Do not reorder, append new values at the end, deprecate old
62 // values and update histograms.xml. 54 // values and update histograms.xml.
63 enum class HitHistogramMetric { 55 enum class HitHistogramMetric {
64 MISS, // Miss, not found in cache. 56 MISS, // Miss, not found in cache.
65 MISS_EXPLICIT_AVOID, // Miss, calle asked to explicitly avoid cache. 57 MISS_EXPLICIT_AVOID, // Miss, calle asked to explicitly avoid cache.
66 MISS_VALIDITY_RECT_MATCHES, // Miss, validity region matches, type doesn 't. 58 MISS_VALIDITY_RECT_MATCHES, // Miss, validity region matches, type doesn 't.
67 HIT_EXACT_MATCH, // Hit, exact point matches. 59 HIT_EXACT_MATCH, // Hit, exact point matches.
68 HIT_REGION_MATCH, // Hit, validity region matches. 60 HIT_REGION_MATCH, // Hit, validity region matches.
69 MAX_HIT_METRIC = HIT_REGION_MATCH, 61 MAX_HIT_METRIC = HIT_REGION_MATCH,
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83 }; 75 };
84 76
85 unsigned m_updateIndex = 0; 77 unsigned m_updateIndex = 0;
86 WillBeHeapVector<HitTestResult, HIT_TEST_CACHE_SIZE> m_items; 78 WillBeHeapVector<HitTestResult, HIT_TEST_CACHE_SIZE> m_items;
87 uint64_t m_domTreeVersion = 0; 79 uint64_t m_domTreeVersion = 0;
88 }; 80 };
89 81
90 } // namespace blink 82 } // namespace blink
91 83
92 #endif // HitTestCache_h 84 #endif // HitTestCache_h
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