1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/ash/power/auto_screen_brightness/als_samples.h"
#include <numeric>
#include "base/check.h"
namespace ash {
namespace power {
namespace auto_screen_brightness {
AmbientLightSampleBuffer::AmbientLightSampleBuffer(base::TimeDelta horizon)
: horizon_(horizon) {
DCHECK(!horizon_.is_zero());
}
AmbientLightSampleBuffer::~AmbientLightSampleBuffer() = default;
void AmbientLightSampleBuffer::SaveToBuffer(
const AmbientLightSampleBuffer::Sample& sample) {
samples_.push_back(sample);
Prune(sample.sample_time);
}
void AmbientLightSampleBuffer::ClearBuffer() {
samples_.clear();
}
std::optional<AlsAvgStdDev> AmbientLightSampleBuffer::AverageAmbientWithStdDev(
base::TimeTicks now) {
Prune(now);
if (samples_.empty())
return std::nullopt;
const size_t count = samples_.size();
double avg = 0;
double stddev = 0;
for (const auto& sample : samples_) {
avg += sample.lux;
stddev += sample.lux * sample.lux;
}
avg = avg / count;
return std::optional<AlsAvgStdDev>(
{avg, std::sqrt(stddev / count - avg * avg)});
}
size_t AmbientLightSampleBuffer::NumberOfSamples(base::TimeTicks now) {
Prune(now);
return samples_.size();
}
size_t AmbientLightSampleBuffer::NumberOfSamplesForTesting() const {
return samples_.size();
}
void AmbientLightSampleBuffer::Prune(base::TimeTicks now) {
while (!samples_.empty()) {
if (now - samples_.front().sample_time < horizon_)
return;
samples_.pop_front();
}
}
} // namespace auto_screen_brightness
} // namespace power
} // namespace ash
|
