lib/common/plugin/compass.js

var exec = require('cordova/exec'),
    utils = require('cordova/utils'),
    CompassHeading = require('cordova/plugin/CompassHeading'),
    CompassError = require('cordova/plugin/CompassError'),
    timers = {},
    compass = {
        /**
         * Asynchronously acquires 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.
         * @param {CompassOptions} options The options for getting the heading data (not used).
         */
        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) {
                var ch = new CompassHeading(result.magneticHeading, result.trueHeading, result.headingAccuracy, result.timestamp);
                successCallback(ch);
            };
            var fail = function(code) {
                var ce = new CompassError(code);
                errorCallback(ce);
            };

            // Get heading
            exec(win, fail, "Compass", "getHeading", [options]);
        },

        /**
         * Asynchronously acquires 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.
         * @param {HeadingOptions} options The options for getting the heading data
         * such as timeout and the frequency of the watch. For iOS, filter parameter
         * specifies to watch via a distance filter rather than time.
         */
        watchHeading:function(successCallback, errorCallback, options) {
            // Default interval (100 msec)
            var frequency = (options !== undefined && options.frequency !== undefined) ? options.frequency : 100;
            var filter = (options !== undefined && options.filter !== undefined) ? options.filter : 0;

            // 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 id = utils.createUUID();
            if (filter > 0) {
                // is an iOS request for watch by filter, no timer needed
                timers[id] = "iOS";
                compass.getCurrentHeading(successCallback, errorCallback, options);
            } else {
                // Start watch timer to get headings
                timers[id] = window.setInterval(function() {
                    compass.getCurrentHeading(successCallback, errorCallback);
                }, frequency);
            }

            return id;
        },

        /**
         * Clears the specified heading watch.
         * @param {String} watchId The ID of the watch returned from #watchHeading.
         */
        clearWatch:function(id) {
            // Stop javascript timer & remove from timer list
            if (id && timers[id]) {
                if (timers[id] != "iOS") {
                      clearInterval(timers[id]);
                  } else {
                    // is iOS watch by filter so call into device to stop
                    exec(null, null, "Compass", "stopHeading", []);
                }
                delete timers[id];
            }
        }
    };

module.exports = compass;