OLD | NEW |
(Empty) | |
| 1 // Copyright 2012 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 |
| 7 #include "rendering_stats_subscriber.h" |
| 8 |
| 9 #include <cmath> |
| 10 |
| 11 namespace { |
| 12 // If a frame takes less than 1/70 seconds, we will assume it is an error and |
| 13 // ignore it. |
| 14 static const double kFrameTooFast = 1.0 / 70.0; |
| 15 } // namespace |
| 16 |
| 17 namespace cc { |
| 18 |
| 19 scoped_ptr<RenderingStatsSubscriber> RenderingStatsSubscriber::create() |
| 20 { |
| 21 scoped_ptr<RenderingStatsSubscriber> subscriber(new RenderingStatsSubscriber); |
| 22 return subscriber.Pass(); |
| 23 } |
| 24 |
| 25 RenderingStatsSubscriber::RenderingStatsSubscriber() |
| 26 : is_scrolling_(false), |
| 27 has_scrolled_(false) |
| 28 {} |
| 29 |
| 30 RenderingStatsSubscriber::~RenderingStatsSubscriber() {} |
| 31 |
| 32 void RenderingStatsSubscriber::markBeginningOfFrame(base::TimeTicks timestamp) { |
| 33 // We ignore timestamps that occur after the scroll. |
| 34 if (has_scrolled_ && !is_scrolling_) |
| 35 return; |
| 36 |
| 37 bool should_add_timestamp = time_stamp_history_.empty(); |
| 38 if (!should_add_timestamp) { |
| 39 base::TimeDelta delta = timestamp - time_stamp_history_.back(); |
| 40 should_add_timestamp = delta.InMillisecondsF() > kFrameTooFast; |
| 41 } |
| 42 if (should_add_timestamp) |
| 43 time_stamp_history_.push_back(timestamp); |
| 44 } |
| 45 |
| 46 void RenderingStatsSubscriber::handledScrollEvent(bool content_did_move) { |
| 47 if (!has_scrolled_ && content_did_move) { |
| 48 // We're starting a scroll. We'll want to measure the framerate during the |
| 49 // scroll, so we'll discard any timestamps we've gathered so far. |
| 50 time_stamp_history_.clear(); |
| 51 has_scrolled_ = true; |
| 52 } |
| 53 |
| 54 is_scrolling_ = content_did_move; |
| 55 } |
| 56 |
| 57 void RenderingStatsSubscriber::getFPSAndStandardDeviation( |
| 58 double& average_fps, |
| 59 double& standard_deviation) const { |
| 60 |
| 61 base::TimeDelta duration = |
| 62 time_stamp_history_.front() - time_stamp_history_.back(); |
| 63 |
| 64 double average_frame_duration = duration.InSecondsF() / |
| 65 static_cast<double>(time_stamp_history_.size()); |
| 66 |
| 67 if (average_frame_duration > 0.0) |
| 68 average_fps = 1.0 / average_frame_duration; |
| 69 |
| 70 if (time_stamp_history_.size() > 2) { |
| 71 double sum_squared_distances_to_mean = 0.0; |
| 72 for (size_t i = 1; i < time_stamp_history_.size(); ++i) { |
| 73 base::TimeDelta frame_duration = |
| 74 time_stamp_history_[i] - time_stamp_history_[i - 1]; |
| 75 double signed_distance_to_mean = |
| 76 average_fps - (1.0 / frame_duration.InSecondsF()); |
| 77 sum_squared_distances_to_mean += |
| 78 signed_distance_to_mean * signed_distance_to_mean; |
| 79 } |
| 80 standard_deviation = std::sqrt(sum_squared_distances_to_mean / |
| 81 static_cast<double>(time_stamp_history_.size() - 2)); |
| 82 } |
| 83 } |
| 84 |
| 85 } // namespace cc |
OLD | NEW |