ui/chromeos/accelerometer/accelerometer_util.cc

   1 // Copyright 2015 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 "ui/chromeos/accelerometer/accelerometer_util.h"
   6
   7 #include <cmath>
   8
   9 #include "chromeos/accelerometer/accelerometer_types.h"
  10 #include "ui/gfx/geometry/vector3d_f.h"
  11
  12 namespace {
  13
  14 // The maximum deviation from the acceleration expected due to gravity for which
  15 // the device will be considered stable: 1g.
  16 const float kDeviationFromGravityThreshold = 1.0f;
  17
  18 // The mean acceleration due to gravity on Earth in m/s^2.
  19 const float kMeanGravity = 9.80665f;
  20
  21 }  // namespace
  22
  23 namespace ui {
  24
  25 const gfx::Vector3dF ConvertAccelerometerReadingToVector3dF(
  26     const chromeos::AccelerometerReading& reading) {
  27   return gfx::Vector3dF(reading.x, reading.y, reading.z);
  28 }
  29
  30 bool IsAccelerometerReadingStable(const chromeos::AccelerometerUpdate& update,
  31                                   chromeos::AccelerometerSource source) {
  32   return update.has(source) &&
  33          std::abs(ConvertAccelerometerReadingToVector3dF(update.get(source))
  34                       .Length() -
  35                   kMeanGravity) <= kDeviationFromGravityThreshold;
  36 }
  37
  38 }  // namespace ui