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Unified Diff: ui/events/gestures/velocity_calculator.cc

Issue 458363002: Remove old Aura Gesture Detection Pipeline. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Address sadrul's comment, and rebase. Created 6 years, 4 months ago
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Index: ui/events/gestures/velocity_calculator.cc
diff --git a/ui/events/gestures/velocity_calculator.cc b/ui/events/gestures/velocity_calculator.cc
deleted file mode 100644
index 37ec671b17f803819197f9f48ff670f2b1bc94b8..0000000000000000000000000000000000000000
--- a/ui/events/gestures/velocity_calculator.cc
+++ /dev/null
@@ -1,114 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "ui/events/gestures/velocity_calculator.h"
-
-namespace ui {
-
-VelocityCalculator::VelocityCalculator(int buffer_size)
- : buffer_(new Point[buffer_size]) ,
- index_(0),
- num_valid_entries_(0),
- buffer_size_(buffer_size),
- x_velocity_(0),
- y_velocity_(0),
- velocities_stale_(false) {
-}
-
-VelocityCalculator::~VelocityCalculator() {}
-
-float VelocityCalculator::XVelocity() {
- if (velocities_stale_)
- UpdateVelocity();
- return x_velocity_;
-}
-
-float VelocityCalculator::YVelocity() {
- if (velocities_stale_)
- UpdateVelocity();
- return y_velocity_;
-}
-
-void VelocityCalculator::PointSeen(float x, float y, int64 time) {
- buffer_[index_].x = x;
- buffer_[index_].y = y;
- buffer_[index_].time = time;
-
- index_ = (index_ + 1) % buffer_size_;
- if (num_valid_entries_ < buffer_size_)
- ++num_valid_entries_;
-
- velocities_stale_ = true;
-}
-
-float VelocityCalculator::VelocitySquared() {
- if (velocities_stale_)
- UpdateVelocity();
- return x_velocity_ * x_velocity_ + y_velocity_ * y_velocity_;
-}
-
-void VelocityCalculator::UpdateVelocity() {
- // We don't have enough data to make a good estimate of the velocity.
- if (num_valid_entries_ < 2)
- return;
-
- // Where A_i = A[i] - mean(A)
- // x velocity = sum_i(x_i * t_i) / sum_i(t_i * t_i)
- // This is an Ordinary Least Squares Regression.
-
- float mean_x = 0;
- float mean_y = 0;
- int64 mean_time = 0;
-
- for (size_t i = 0; i < num_valid_entries_; ++i) {
- mean_x += buffer_[i].x;
- mean_y += buffer_[i].y;
- mean_time += buffer_[i].time;
- }
-
- // Minimize number of divides.
- const float num_valid_entries_i = 1.0f / num_valid_entries_;
-
- mean_x *= num_valid_entries_i;
- mean_y *= num_valid_entries_i;
-
- // The loss in accuracy due to rounding is insignificant compared to
- // the error due to the resolution of the timer.
- // Use integer division to avoid the cast to double, which would cause
- // VelocityCalculatorTest.IsAccurateWithLargeTimes to fail.
- mean_time /= num_valid_entries_;
-
- float xt = 0; // sum_i(x_i * t_i)
- float yt = 0; // sum_i(y_i * t_i)
- int64 tt = 0; // sum_i(t_i * t_i)
-
- int64 t_i;
-
- for (size_t i = 0; i < num_valid_entries_; ++i) {
- t_i = (buffer_[i].time - mean_time);
- xt += (buffer_[i].x - mean_x) * t_i;
- yt += (buffer_[i].y - mean_y) * t_i;
- tt += t_i * t_i;
- }
-
- if (tt > 0) {
- // Convert time from microseconds to seconds.
- x_velocity_ = xt / (tt / 1000000.0f);
- y_velocity_ = yt / (tt / 1000000.0f);
- } else {
- x_velocity_ = 0.0f;
- y_velocity_ = 0.0f;
- }
- velocities_stale_ = false;
-}
-
-void VelocityCalculator::ClearHistory() {
- index_ = 0;
- num_valid_entries_ = 0;
- x_velocity_ = 0;
- y_velocity_ = 0;
- velocities_stale_ = false;
-}
-
-} // namespace ui
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