Remove old Aura Gesture Detection Pipeline.

ui/events/gestures/velocity_calculator.cc

-// 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