terriajs
Version:
Geospatial data visualization platform.
145 lines (131 loc) • 6.4 kB
JavaScript
;
/*global require*/
var defined = require('terriajs-cesium/Source/Core/defined');
var loadJson = require('../Core/loadJson');
var DeveloperError = require('terriajs-cesium/Source/Core/DeveloperError');
var RegionProvider = require('./RegionProvider');
/**********************************************************************************************
* Region mapping support - turn CSVs into choropleths of regions like local government areas
* Implements most of https://github.com/TerriaJS/nationalmap/wiki/csv-geo-au
* How this works:
* 1. If there are 'lat' and 'lon' columns, use those instead to generate a point display.
* 2. Look through all the column names in the CSV file until we find one that matches a defined region descriptor in
region mapping JSON file (not included in TerriaJS)
* 3. Contact the WFS server defined in that file, fetch IDs for all regions of that type
* 4. Based on values in the region variable column, generate a linear choropleth mapping
* 5. Fetch specially prepared WMS tiles which are coloured with a unique colour per region.
* 6. Recolor each tile, using the unique colour to determine its ID, then replacing that unique colour with a mapped color.
*
* Voilà - very fast client-side choroplething with no user data sent to servers, and no vector boundaries sent to client. */
/**
* RegionProviderList encapsulates the regionMapping.json file and provides support for choosing the best region
* provider for a given dataset.
*
* @alias RegionProviderList
* @constructor
* @param corsProxy A proxy to allow the region providers to make AJAX calls safely.
*/
var RegionProviderList = function(corsProxy) {
/**
* List of RegionProviders, once loaded from file.
* @type {RegionProvider[]}
*/
this.regionProviders = [];
// To be passed to new RegionProviders
this.corsProxy = corsProxy;
};
/* A static dictionary of promises to RegionProviderLists */
RegionProviderList.metaList = {};
/**
* Returns a promise for a RegionProviderList instantiated from this url. Previous loads are cached.
*
* @param {String} url
* @returns {Promise} A promise for a RegionProviderList instantiated from this url.
*/
RegionProviderList.fromUrl = function(url, corsProxy) {
if (!defined(RegionProviderList.metaList[url])) {
RegionProviderList.metaList[url] = loadJson(url)
.then(function(o) {
return new RegionProviderList(corsProxy).initFromObject(o);
});
}
return RegionProviderList.metaList[url];
};
/**
* Initialises from the already-retrieved contents of a JSON file.
*
* @param {Object} obj
*/
RegionProviderList.prototype.initFromObject = function(obj) {
var that = this;
Object.keys(obj.regionWmsMap).forEach(function(r) {
that.regionProviders.push(new RegionProvider(r, obj.regionWmsMap[r], that.corsProxy));
});
// after loading all providers, now we can set cross references for disambiguation, where required.
Object.keys(obj.regionWmsMap).forEach(function(r) {
var rp = that.getRegionProvider(r);
if (obj.regionWmsMap[r].disambigRegionId) {
rp.setDisambigProperties(that.getRegionProvider(obj.regionWmsMap[r].disambigRegionId));
}
});
return this;
};
/**
* Find what kind of region-mapped dataset this is by exhaustively looking for every alias for every variable name provided.
* You can optionally provide a prefered region variable name, and optionally its prefered type.
* If specified, getRegionDetails will return that name as the first object in the returned array.
*
* @param variableNames {String[]} Array of names of variables to choose amongst.
* @param variableNames {String[]} Array of names of variables to choose amongst.
* @return {Object[]} An array of objects with regionProvider (RegionProvider), regionVariable and disambigVariable properties, for each potential region variable in the list of names.
*/
RegionProviderList.prototype.getRegionDetails = function(variableNames, preferedRegionVariableName, preferedRegionType) {
var results = [];
// If preferedRegionVariableName is in variableNames (which it must be to be meaningful; if undefined, it won't be), remove it first.
var index = variableNames.indexOf(preferedRegionVariableName);
if (index >= 0) {
variableNames = variableNames.slice(); // clone it so we don't potentially confuse the caller.
variableNames.splice(index, 1);
if (!defined(preferedRegionType)) {
// If no type is provided, simply put this back in the front of the array, to prioritize it.
variableNames.unshift(preferedRegionVariableName);
} else {
// If a type is provided, handle it specially.
var regionProvider = this.getRegionProvider(preferedRegionType);
results.push({
regionProvider: regionProvider,
variableName: preferedRegionVariableName,
disambigVariableName: regionProvider.findDisambigVariable(variableNames)
});
}
}
// Figure out the region variable and type based on aliases.
for (var i = 0; i < this.regionProviders.length; i++) {
var rv = this.regionProviders[i].findRegionVariable(variableNames);
if (rv) {
results.push({
regionProvider: this.regionProviders[i],
variableName: rv,
disambigVariableName: this.regionProviders[i].findDisambigVariable(variableNames)
});
}
}
return results;
};
/**
* Get the region provider matching a regionType string (eg, STE)
*
* @param {String} regionType The type string to look up.
* @return {RegionProvider} The region provider matching a regionType string (eg, STE), or undefined.
*/
RegionProviderList.prototype.getRegionProvider = function(regionType) {
var r = this.regionProviders.filter(function(p) { return p.regionType.toLowerCase() === regionType.toLowerCase(); });
if (r.length > 1) {
throw new DeveloperError ('More than one definition of region provider: ' + regionType);
}
if (r.length === 0) {
return undefined;
}
return r[0];
};
module.exports = RegionProviderList;