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// Copyright (c) 2010 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.
// A location provider provides position information from a particular source
// (GPS, network etc). The GearsGeolocation object uses a set of location
// providers to obtain a position fix.
//
// This file declares a base class to be used by all location providers.
// Primarily, this class declares interface methods to be implemented by derived
// classes.
#ifndef CHROME_BROWSER_GEOLOCATION_LOCATION_PROVIDER_H_
#define CHROME_BROWSER_GEOLOCATION_LOCATION_PROVIDER_H_
#include <map>
#include "base/non_thread_safe.h"
#include "base/string16.h"
class AccessTokenStore;
struct Geoposition;
class GURL;
class URLRequestContextGetter;
// The base class used by all location providers.
class LocationProviderBase : public NonThreadSafe {
public:
// Clients of the location provider must implement this interface. All call-
// backs to this interface will happen in the context of the thread on which
// the location provider was created.
class ListenerInterface {
public:
// Used to inform listener that a new position fix is available or that a
// fatal error has occurred. Providers should call this for new listeners
// as soon as a position is available.
virtual void LocationUpdateAvailable(LocationProviderBase* provider) = 0;
protected:
virtual ~ListenerInterface() {}
};
virtual ~LocationProviderBase();
// Registers a listener, which will be called back on
// ListenerInterface::LocationUpdateAvailable as soon as a position is
// available and again whenever a new position is available. Ref counts the
// listener to handle multiple calls to this method.
void RegisterListener(ListenerInterface* listener);
// Unregisters a listener. Unrefs the listener to handle multiple calls to
// this method. Once the ref count reaches zero, the listener is removed and
// once this method returns, no further calls to
// ListenerInterface::LocationUpdateAvailable will be made for this listener.
// It may block if a callback is in progress.
void UnregisterListener(ListenerInterface* listener);
// Interface methods
// StartProvider maybe called multiple times, e.g. to alter the
// |high_accuracy| setting. Returns false if a fatal error was encountered
// which prevented the provider from starting.
virtual bool StartProvider(bool high_accuracy) = 0;
virtual void StopProvider() = 0;
// Gets the current best position estimate.
virtual void GetPosition(Geoposition* position) = 0;
// Provides a hint to the provider that new location data is needed as soon
// as possible. Default implementation does nothing.
virtual void UpdatePosition() {}
// Delegated to the provider by GeolocationArbitrator. See the corresponding
// method on that class for more details.
virtual void OnPermissionGranted(const GURL& requesting_frame) {}
bool has_listeners() const;
protected:
LocationProviderBase();
// Inform listeners that a new position or error is available, using
// LocationUpdateAvailable.
void UpdateListeners();
private:
// The listeners registered to this provider. For each listener, we store a
// ref count.
typedef std::map<ListenerInterface*, int> ListenerMap;
ListenerMap listeners_;
};
// Factory functions for the various types of location provider to abstract over
// the platform-dependent implementations.
LocationProviderBase* NewGpsLocationProvider();
LocationProviderBase* NewNetworkLocationProvider(
AccessTokenStore* access_token_store,
URLRequestContextGetter* context,
const GURL& url,
const string16& access_token);
#endif // CHROME_BROWSER_GEOLOCATION_LOCATION_PROVIDER_H_
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