map/esriMap.js

'use strict';
const basemap = require('./basemap.js');
const mapPrint = require('./print.js');

function esriMap(esriBundle, geoApi) {

    const printModule = mapPrint(esriBundle);

    class Map {

        static get Extent () { return esriBundle.Extent; }
        get _passthroughBindings () { return ['on', 'reorderLayer', 'addLayer', 'disableKeyboardNavigation']; } // TODO when jshint parses instance fields properly we can change this from a property to a field
        get _passthroughProperties () { return ['graphicsLayerIds', 'layerIds', 'spatialReference']; } // TODO when jshint parses instance fields properly we can change this from a property to a field

        constructor (domNode, opts) {

            this._passthroughBindings.forEach(bindingName =>
                this[bindingName] = (...args) => this._map[bindingName](...args));
            this._passthroughProperties.forEach(propName => {
                const descriptor = {
                    enumerable: true,
                    get: () => this._map[propName]
                };
                Object.defineProperty(this, propName, descriptor);
            });

            this._map = new esriBundle.Map(domNode, { extent: opts.extent, lods: opts.lods });
            if (opts.proxyUrl) {
                this.proxy = opts.proxyUrl;
            }

            if (opts.basemaps) {
                this.basemapGallery = basemap.initBasemaps(esriBundle, opts.basemaps, this._map);
                this.basemapGallery.on('selection-change', () => this.resetOverviewMap());
            } else {
                throw new Error('The basemaps option is required to and at least one basemap must be defined');
            }

            if (opts.scalebar) {
                this.scalebar = new esriBundle.Scalebar({
                    map: this._map,
                    attachTo: opts.scalebar.attachTo,
                    scalebarUnit: opts.scalebar.scalebarUnit
                });
                this.scalebar.show();
            }

            if (opts.overviewMap) {
                this.initOverviewMap();
            }

        }

        printLocal (options) { return printModule.printLocal(this._map, options); }
        printServer (options) { return printModule.printServer(this._map, options); }

        /**
         * Create an ESRI Extent object from extent setting JSON object.
         *
         * @function getExtentFromJson
         * @param {Object} extentJson that follows config spec
         * @return {Object} an ESRI Extent object
         */
        static getExtentFromJson (extentJson) {

            return esriBundle.Extent({ xmin: extentJson.xmin, ymin: extentJson.ymin,
                xmax: extentJson.xmax, ymax: extentJson.ymax,
                spatialReference: { wkid: extentJson.spatialReference.wkid } });
        }

        /**
         * Finds the level of detail closest to the provided scale.
         *
         * @function findClosestLOD
         * @param  {Array} lods     list of levels of detail objects
         * @param  {Number} scale   scale value to search for in the levels of detail
         * @return {Object}         the level of detail object closest to the scale
         */
        static findClosestLOD (lods, scale) {
            const diffs = lods.map(lod => Math.abs(lod.scale - scale));
            const lodIdx = diffs.indexOf(Math.min(...diffs));
            return lods[lodIdx];
        }

        /**
         * Calculate north arrow bearing. Angle returned is to to rotate north arrow image.
         * http://www.movable-type.co.uk/scripts/latlong.html
         * @function getNorthArrowAngle
         * @returns {Number} map rotation angle (in degree)
         */
        getNorthArrowAngle () {
            // get center point in longitude and use bottom value for latitude
            const pointB = geoApi.proj.localProjectPoint(this._map.extent.spatialReference, 'EPSG:4326',
                    { x: (this._map.extent.xmin + this._map.extent.xmax) / 2, y: this._map.extent.ymin });

            // north value (set longitude to be half of Canada extent (141° W, 52° W))
            const pointA = { x: -96, y: 90 };

            // set info on longitude and latitude
            const dLon = (pointB.x - pointA.x) * Math.PI / 180;
            const lat1 = pointA.y * Math.PI / 180;
            const lat2 = pointB.y * Math.PI / 180;

            // calculate bearing
            const y = Math.sin(dLon) * Math.cos(lat2);
            const x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) * Math.cos(lat2) * Math.cos(dLon);
            const bearing = Math.atan2(y, x) * 180 / Math.PI;

            // return angle (180 is pointiong north)
            return ((bearing + 360) % 360).toFixed(1);
        }

        /**
         * Calculate distance between min and max extent to know the pixel ratio between
         * screen size and earth distance.
         * http://www.movable-type.co.uk/scripts/latlong.html
         * @function getScaleRatio
         * @param {Number} mapWidth optional the map width to use to calculate ratio
         * @returns {Object} contain information about the scale
         *                               - distance: distance between min and max extentId
         *                               - ratio: measure for 1 pixel in earth distance
         *                               - units: array of units [metric, imperial]
         */
        getScaleRatio (mapWidth = 0) {
            const map = this._map;

            // get left and right maximum value point to calculate distance from
            const pointA = geoApi.proj.localProjectPoint(map.spatialReference, 'EPSG:4326',
                    { x: map.extent.xmin, y: (map.extent.ymin + map.extent.ymax) / 2 });
            const pointB = geoApi.proj.localProjectPoint(map.spatialReference, 'EPSG:4326',
                    { x: map.extent.xmax, y: (map.extent.ymin + map.extent.ymax) / 2 });

            // Haversine formula to calculate distance
            const R = 6371e3; // earth radius in meters
            const rad = Math.PI / 180;
            const phy1 = pointA.y * rad; // radiant
            const phy2 = pointB.y * rad; // radiant
            const deltaPhy = (pointB.y - pointA.y) * rad; // radiant
            const deltaLambda = (pointB.x - pointA.x) * rad; // radiant

            const a = Math.sin(deltaPhy / 2) * Math.sin(deltaPhy / 2) +
                        Math.cos(phy1) * Math.cos(phy2) *
                        Math.sin(deltaLambda / 2) * Math.sin(deltaLambda / 2);
            const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
            const d = (R * c);

            // set map / image width (if mapWidth = 0, use map.width)
            const width = mapWidth ? mapWidth : map.width;

            // get unit from distance, set distance and ratio (earth size for 1 pixel)
            const units = [(d > 1000) ? 'km' : 'm', (d > 1600) ? 'mi' : 'ft'];
            const distance = (d > 1000) ? d / 1000 : d;
            const ratio = distance / width;

            return { distance, ratio, units };
        }

        /**
         * Compares to sets of co-ordinates for extents (valid for both x and y). If center of input co-ordinates falls outside
         * map co-ordiantes, function will adjust them so the center is inside the map co-ordinates.
         *
         * @function clipExtentCoords
         * @private
         * @param {Numeric} mid      middle of the the range to test
         * @param {Numeric} max      maximum value of the range to test
         * @param {Numeric} min      minimum value of the range to test
         * @param {Numeric} mapMax   maximum value of the map range
         * @param {Numeric} mapMin   minimum value of the map range
         * @param {Numeric} len      length of the adjusted range, if adjusted
         * @return {Array}           two element array of Numeric, containing result max and min values
         */
        static clipExtentCoords (mid, max, min, mapMax, mapMin, len) {

            if (mid > mapMax) {
                [max, min] = [mapMax, mapMax - len];
            } else if (mid < mapMin) {
                [max, min] = [mapMin + len, mapMin];
            }
            return [max, min];
        }

        /**
         * Checks if the center of the given extent is outside of the maximum extent. If it is,
         * will determine an adjusted extent with a center inside the maximum extent.  Returns both
         * an indicator flag if an adjustment happened, and the adjusted extent.
         *
         * @function enforceBoundary
         * @param {Object} extent      an ESRI extent to test
         * @param {Object} maxExtent   an ESRI extent indicating the boundary of the map
         * @return {Object}            an object with two properties. adjusted - boolean, true if extent was adjusted. newExtent - object, adjusted ESRI extent
         */
        static enforceBoundary (extent, maxExtent) {
            // clone extent
            const newExtent = esriBundle.Extent(extent.toJson());

            // determine dimensions of adjusted extent.
            // same as input, unless input is so large it consumes max.
            // in that case, we shrink to the max. This avoids the "washing machine"
            // bug where we over-correct past the valid range,
            // and achieve infinite oscillating pans
            const height = Math.min(extent.getHeight(), maxExtent.getHeight());
            const width = Math.min(extent.getWidth(), maxExtent.getWidth());
            const center = extent.getCenter();

            [newExtent.xmax, newExtent.xmin] =
                this.clipExtentCoords(center.x, newExtent.xmax, newExtent.xmin, maxExtent.xmax, maxExtent.xmin, width);
            [newExtent.ymax, newExtent.ymin] =
                this.clipExtentCoords(center.y, newExtent.ymax, newExtent.ymin, maxExtent.ymax, maxExtent.ymin, height);

            return {
                newExtent,
                adjusted: !extent.contains(newExtent) // true if we adjusted the extent
            };
        }

        initOverviewMap () {
            this.overviewMap = new esriBundle.OverviewMap({ map: this._map, expandFactor: 1, visible: true });
            this.overviewMap.startup();
        }
        resetOverviewMap () {
            this.overviewMap.destroy();
            this.initOverviewMap();
        }

        /**
         * Sets or gets map default config values.
         *
         * @function mapDefault
         * @param {String} key  name of the default property
         * @param {Any} [value] optional value to set for the specified default property
         */
        mapDefault (key, value) {
            if (typeof value === 'undefined') {
                return esriBundle.esriConfig.defaults.map[key];
            } else {
                esriBundle.esriConfig.defaults.map[key] = value;
            }
        }

        /**
         * Set proxy service URL to avoid same origin issues.
         */
        set proxy (proxyUrl) { esriBundle.esriConfig.defaults.io.proxyUrl = proxyUrl; }
        get proxy () { return esriBundle.esriConfig.defaults.io.proxyUrl; }

        set basemapGallery (val) { this._basemapGallery = val; }
        get basemapGallery () { return this._basemapGallery; }

        set scalebar (val) { this._scalebar = val; }
        get scalebar () { return this._scalebar; }

        set overviewMap (val) { this._overviewMap = val; }
        get overviewMap () { return this._overviewMap; }

    }

    return Map;
}

/**
  * The `MapManager` module exports an object with the following properties:
  * - `Extent` esri/geometry type
  * - `Map` esri/map type
  * - `OverviewMap` esri/dijit/OverviewMap type
  * - `Scalebar` sri/dijit/Scalebar type
  * - `getExtentFromSetting function to create an ESRI Extent object from extent setting JSON object.
  * - `setupMap` function that interates over config settings and apply logic for any items present.
  * - `setProxy` function to set proxy service URL to avoid same origin issues
  */

// mapManager module, provides function to setup a map
module.exports = (esriBundle, geoApi) => esriMap(esriBundle, geoApi);