1/*
2 * Copyright (C) 2018 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28namespace WebCore {
29
30// This class is used to detect when we are painting frequently so that - even in a painting model
31// without display lists - we can build and cache portions of display lists and reuse them only when
32// animating. Once we transition fully to display lists, we can probably just pull from the previous
33// paint's display list if it is still around and get rid of this code.
34class PaintFrequencyTracker {
35 WTF_MAKE_FAST_ALLOCATED;
36
37public:
38 PaintFrequencyTracker() = default;
39
40 void begin()
41 {
42 static unsigned paintFrequencyPaintCountThreshold = 30;
43 static Seconds paintFrequencyTimePerFrameThreshold = 32_ms;
44 static Seconds paintFrequencySecondsIdleThreshold = 5_s;
45
46 // Start by assuming the paint frequency is low
47 m_paintFrequency = PaintFrequency::Low;
48
49 MonotonicTime now = MonotonicTime::now();
50 if (!m_firstPaintTime) {
51 // Handle the first time this method is called.
52 m_firstPaintTime = now;
53 } else if (now - m_lastPaintTime > paintFrequencySecondsIdleThreshold) {
54 // It has been 5 seconds since last time we draw this renderer. Reset the state
55 // of this object as if, we've just started tracking the paint frequency.
56 m_firstPaintTime = now;
57 m_totalPaints = 0;
58 } else if (m_totalPaints >= paintFrequencyPaintCountThreshold && ((m_lastPaintTime - m_firstPaintTime) / m_totalPaints) <= paintFrequencyTimePerFrameThreshold) {
59 // Change the paint frequency to be high only if:
60 // - This renderer has been painted at least 30 times.
61 // - The frame rate to paint this renderer has been at least 31.25 FPS.
62 m_paintFrequency = PaintFrequency::High;
63 }
64 }
65
66 void end()
67 {
68 m_lastPaintTime = MonotonicTime::now();
69 ASSERT(m_firstPaintTime);
70 ASSERT(m_firstPaintTime <= m_lastPaintTime);
71 ++m_totalPaints;
72 }
73
74 bool paintingFrequently() const { return m_paintFrequency == PaintFrequency::High; }
75
76private:
77 MonotonicTime m_firstPaintTime;
78 MonotonicTime m_lastPaintTime;
79 unsigned m_totalPaints { 0 };
80
81 enum class PaintFrequency { Low, High };
82 PaintFrequency m_paintFrequency { PaintFrequency::Low };
83};
84
85class SinglePaintFrequencyTracking {
86 WTF_MAKE_FAST_ALLOCATED;
87public:
88 SinglePaintFrequencyTracking(PaintFrequencyTracker& paintFrequencyTracker, bool track = true)
89 : m_paintFrequencyTracker(paintFrequencyTracker)
90 , m_track(track)
91 {
92 if (m_track)
93 m_paintFrequencyTracker.begin();
94 }
95
96 ~SinglePaintFrequencyTracking()
97 {
98 if (m_track)
99 m_paintFrequencyTracker.end();
100 }
101
102private:
103 PaintFrequencyTracker& m_paintFrequencyTracker;
104 bool m_track;
105};
106
107}
108