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// Copyright (c) 2011 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 "content/browser/geolocation/win7_location_provider_win.h"
#include <algorithm>
#include <cmath>
#include "base/bind.h"
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "base/message_loop.h"
namespace{
const int kPollPeriodMovingMillis = 500;
// Poll less frequently whilst stationary.
const int kPollPeriodStationaryMillis = kPollPeriodMovingMillis * 3;
// Reading must differ by more than this amount to be considered movement.
const int kMovementThresholdMeters = 20;
// This algorithm is reused from the corresponding code in the Gears project
// and is also used in gps_location_provider_linux.cc
// The arbitrary delta is decreased (Gears used 100 meters); if we need to
// decrease it any further we'll likely want to do some smarter filtering to
// remove GPS location jitter noise.
bool PositionsDifferSiginificantly(const Geoposition& position_1,
const Geoposition& position_2) {
const bool pos_1_valid = position_1.IsValidFix();
if (pos_1_valid != position_2.IsValidFix())
return true;
if (!pos_1_valid) {
DCHECK(!position_2.IsValidFix());
return false;
}
double delta = std::sqrt(
std::pow(std::fabs(position_1.latitude - position_2.latitude), 2) +
std::pow(std::fabs(position_1.longitude - position_2.longitude), 2));
// Convert to meters. 1 minute of arc of latitude (or longitude at the
// equator) is 1 nautical mile or 1852m.
delta *= 60 * 1852;
return delta > kMovementThresholdMeters;
}
}
Win7LocationProvider::Win7LocationProvider(Win7LocationApi* api)
: ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)) {
DCHECK(api != NULL);
api_.reset(api);
}
Win7LocationProvider::~Win7LocationProvider() {
api_.reset();
}
bool Win7LocationProvider::StartProvider(bool high_accuracy){
if (api_ == NULL)
return false;
api_->SetHighAccuracy(high_accuracy);
if (!weak_factory_.HasWeakPtrs())
ScheduleNextPoll(0);
return true;
}
void Win7LocationProvider::StopProvider() {
weak_factory_.InvalidateWeakPtrs();
}
void Win7LocationProvider::GetPosition(Geoposition* position) {
DCHECK(position);
*position = position_;
}
void Win7LocationProvider::UpdatePosition() {
ScheduleNextPoll(0);
}
void Win7LocationProvider::OnPermissionGranted(
const GURL& requesting_frame) {
}
void Win7LocationProvider::DoPollTask() {
Geoposition new_position;
api_->GetPosition(&new_position);
const bool differ = PositionsDifferSiginificantly(position_, new_position);
ScheduleNextPoll(differ ? kPollPeriodMovingMillis :
kPollPeriodStationaryMillis);
if (differ || new_position.error_code != Geoposition::ERROR_CODE_NONE) {
// Update if the new location is interesting or we have an error to report
position_ = new_position;
UpdateListeners();
}
}
void Win7LocationProvider::ScheduleNextPoll(int interval) {
MessageLoop::current()->PostDelayedTask(
FROM_HERE,
base::Bind(&Win7LocationProvider::DoPollTask, weak_factory_.GetWeakPtr()),
interval);
}
LocationProviderBase* NewSystemLocationProvider() {
Win7LocationApi* api = Win7LocationApi::Create();
if (api == NULL)
return NULL; // API not supported on this machine.
return new Win7LocationProvider(api);
}
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