cordova-android/framework/assets/js/compass.js

/*
 *     Licensed to the Apache Software Foundation (ASF) under one
 *     or more contributor license agreements.  See the NOTICE file
 *     distributed with this work for additional information
 *     regarding copyright ownership.  The ASF licenses this file
 *     to you under the Apache License, Version 2.0 (the
 *     "License"); you may not use this file except in compliance
 *     with the License.  You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *     Unless required by applicable law or agreed to in writing,
 *     software distributed under the License is distributed on an
 *     "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *     KIND, either express or implied.  See the License for the
 *     specific language governing permissions and limitations
 *     under the License.
 */

if (!Cordova.hasResource("compass")) {
Cordova.addResource("compass");

var CompassError = function(){
    this.code = null;
};

// Capture error codes
CompassError.COMPASS_INTERNAL_ERR = 0;
CompassError.COMPASS_NOT_SUPPORTED = 20;

var CompassHeading = function() {
    this.magneticHeading = null;
    this.trueHeading = null;
    this.headingAccuracy = null;
    this.timestamp = null;
};

/**
 * This class provides access to device Compass data.
 * @constructor
 */
var Compass = function() {
    /**
     * The last known Compass position.
     */
    this.lastHeading = null;

    /**
     * List of compass watch timers
     */
    this.timers = {};
};

Compass.ERROR_MSG = ["Not running", "Starting", "", "Failed to start"];

/**
 * Asynchronously aquires the current heading.
 *
 * @param {Function} successCallback The function to call when the heading data is available
 * @param {Function} errorCallback The function to call when there is an error getting the heading data. (OPTIONAL)
 * @param {PositionOptions} options The options for getting the heading data such as timeout. (OPTIONAL)
 */
Compass.prototype.getCurrentHeading = function(successCallback, errorCallback, options) {

    // successCallback required
    if (typeof successCallback !== "function") {
        console.log("Compass Error: successCallback is not a function");
        return;
    }

    // errorCallback optional
    if (errorCallback && (typeof errorCallback !== "function")) {
        console.log("Compass Error: errorCallback is not a function");
        return;
    }
    
    var win = function(result) {
        if (result.timestamp) {
            var timestamp = new Date(result.timestamp);
            result.timestamp = timestamp;
        }
        successCallback(result);   
    };

    // Get heading
    Cordova.exec(win, errorCallback, "Compass", "getHeading", []);
};

/**
 * Asynchronously aquires the heading repeatedly at a given interval.
 *
 * @param {Function} successCallback    The function to call each time the heading data is available
 * @param {Function} errorCallback      The function to call when there is an error getting the heading data. (OPTIONAL)
 * @param {HeadingOptions} options      The options for getting the heading data such as timeout and the frequency of the watch. (OPTIONAL)
 * @return String                       The watch id that must be passed to #clearWatch to stop watching.
 */
Compass.prototype.watchHeading= function(successCallback, errorCallback, options) {

    // Default interval (100 msec)
    var frequency = (options !== undefined) ? options.frequency : 100;

    // successCallback required
    if (typeof successCallback !== "function") {
        console.log("Compass Error: successCallback is not a function");
        return;
    }

    // errorCallback optional
    if (errorCallback && (typeof errorCallback !== "function")) {
        console.log("Compass Error: errorCallback is not a function");
        return;
    }

    // Make sure compass timeout > frequency + 10 sec
    Cordova.exec(
        function(timeout) {
            if (timeout < (frequency + 10000)) {
                Cordova.exec(null, null, "Compass", "setTimeout", [frequency + 10000]);
            }
        },
        function(e) { }, "Compass", "getTimeout", []);

    // Start watch timer to get headings
    var id = Cordova.createUUID();
    navigator.compass.timers[id] = setInterval(
        function() {
            var win = function(result) {
                if (result.timestamp) {
                    var timestamp = new Date(result.timestamp);
                    result.timestamp = timestamp;
                }
                successCallback(result);   
            };
            Cordova.exec(win, errorCallback, "Compass", "getHeading", []);
        }, (frequency ? frequency : 1));

    return id;
};


/**
 * Clears the specified heading watch.
 *
 * @param {String} id       The ID of the watch returned from #watchHeading.
 */
Compass.prototype.clearWatch = function(id) {

    // Stop javascript timer & remove from timer list
    if (id && navigator.compass.timers[id]) {
        clearInterval(navigator.compass.timers[id]);
        delete navigator.compass.timers[id];
    }
};

Compass.prototype._castDate = function(pluginResult) {
    if (pluginResult.message.timestamp) {
        var timestamp = new Date(pluginResult.message.timestamp);
        pluginResult.message.timestamp = timestamp;
    }
    return pluginResult;
};

Cordova.addConstructor(function() {
    if (typeof navigator.compass === "undefined") {
        navigator.compass = new Compass();
    }
});
}