content/browser/device_orientation/orientation.cc

   1 // Copyright (c) 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 "content/browser/device_orientation/orientation.h"
   6
   7 #include <cmath>
   8
   9 #include "content/common/device_orientation_messages.h"
  10
  11 namespace content {
  12
  13 Orientation::Orientation()
  14     : can_provide_alpha_(false),
  15       can_provide_beta_(false),
  16       can_provide_gamma_(false),
  17       can_provide_absolute_(false) {
  18 }
  19
  20 Orientation::~Orientation() {
  21 }
  22
  23 IPC::Message* Orientation::CreateIPCMessage(int render_view_id) const {
  24   DeviceOrientationMsg_Updated_Params params;
  25   params.can_provide_alpha = can_provide_alpha_;
  26   params.alpha = alpha_;
  27   params.can_provide_beta = can_provide_beta_;
  28   params.beta = beta_;
  29   params.can_provide_gamma = can_provide_gamma_;
  30   params.gamma = gamma_;
  31   params.can_provide_absolute = can_provide_absolute_;
  32   params.absolute = absolute_;
  33
  34   return new DeviceOrientationMsg_Updated(render_view_id, params);
  35 }
  36
  37 // Returns true if two orientations are considered different enough that
  38 // observers should be notified of the new orientation.
  39 bool Orientation::ShouldFireEvent(const DeviceData* old_data) const {
  40   scoped_refptr<const Orientation> old_orientation(
  41       static_cast<const Orientation*>(old_data));
  42
  43   return IsElementSignificantlyDifferent(can_provide_alpha_,
  44                                          old_orientation->can_provide_alpha(),
  45                                          alpha_,
  46                                          old_orientation->alpha()) ||
  47         IsElementSignificantlyDifferent(can_provide_beta_,
  48                                         old_orientation->can_provide_beta(),
  49                                         beta_,
  50                                         old_orientation->beta()) ||
  51         IsElementSignificantlyDifferent(can_provide_gamma_,
  52                                         old_orientation->can_provide_gamma(),
  53                                         gamma_,
  54                                         old_orientation->gamma()) ||
  55         can_provide_absolute_ != old_orientation->can_provide_absolute() ||
  56         absolute_ != old_orientation->absolute();
  57 }
  58
  59 bool Orientation::IsElementSignificantlyDifferent(bool can_provide_element1,
  60     bool can_provide_element2, double element1, double element2) {
  61   const double kThreshold = 0.1;
  62
  63   if (can_provide_element1 != can_provide_element2)
  64     return true;
  65   if (can_provide_element1 && std::fabs(element1 - element2) >= kThreshold)
  66     return true;
  67   return false;
  68 }
  69
  70 }  // namespace content