device/geolocation/public/interfaces/geolocation.mojom

// Copyright 2014 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.

module device.mojom;

// A Geoposition represents a position fix. It was originally derived from:
// http://gears.googlecode.com/svn/trunk/gears/geolocation/geolocation.h
// TODO(blundell): Investigate killing content::Geoposition in favor of using
// this struct everywhere.
struct Geoposition {
  // These values follow the W3C geolocation specification and can be returned
  // to JavaScript without the need for a conversion.
  enum ErrorCode {
    NONE = 0,  // Chrome addition.
    PERMISSION_DENIED = 1,
    POSITION_UNAVAILABLE = 2,
    TIMEOUT = 3,
    LAST = TIMEOUT
  };

  // Whether this geoposition is valid.
  bool valid;

  // These properties correspond to those of the JavaScript Position object
  // although their types may differ.
  // Latitude in decimal degrees north (WGS84 coordinate frame).
  double latitude;
  // Longitude in decimal degrees west (WGS84 coordinate frame).
  double longitude;
  // Altitude in meters (above WGS84 datum).
  double altitude;
  // Accuracy of horizontal position in meters.
  double accuracy;
  // Accuracy of altitude in meters.
  double altitude_accuracy;
  // Heading in decimal degrees clockwise from true north.
  double heading;
  // Horizontal component of device velocity in meters per second.
  double speed;
  // TODO(blundell): If I need to represent this differently to use this
  // struct to replace content::Geolocation, I'll need to convert
  // correctly into seconds-since-epoch when using this in
  // GeolocationDispatcher::OnLocationUpdate().
  // Time of position measurement in seconds since Epoch in UTC time. This is
  // taken from the host computer's system clock (i.e. from Time::Now(), not the
  // source device's clock).
  double timestamp;

  // Error code, see enum above.
  ErrorCode error_code;
  // Human-readable error message.
  string error_message;
};

// The Geolocation service provides updates on the device's location.  By
// default, it provides updates with low accuracy, but |SetHighAccuracy()| may
// be called to change this.
interface GeolocationService {
  SetHighAccuracy(bool high_accuracy);

  // Position is reported once it changes or immediately (to report the initial
  // position) if this is the first call to QueryNextPosition on this instance.
  // Position updates may be throttled by the service. Overlapping calls to
  // this method are prohibited and will be treated as a connection error.
  QueryNextPosition() => (Geoposition geoposition);
};