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cluster.js
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cluster.js
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/* global H, document, Image */
"use strict";
const cm = require("./common.js");
const m = require("./map.js");
// map on which to add the cluster layer
let map = null;
//the cluster layer
let clusterLayer = null;
let _visible = false;
let iconNoise = null;
let clusterStyle = []; // array of {weight,pos imagedata}
let clusteredDataProvider = null;
/**
* Creates a cluster of points
* @alias hm:cluster
* @param coords {Array} array of \[lat,lng,payload\]
* @param opt {object} options for cluster
* @param [opt.minZoom] {number} min zoom for cluster to be visible
* @param [opt.maxZoom] {number} max zoom for cluster to be visible
* @param [opt.noise] {object} graphic to represent stand-alone point. {icon,size}
* @param [opt.noise.icon] {string} png/jpg/svg file. @ as first character indicates a file from this package. Anchor will be bottom-center
* @param [opt.noise.size] {number} optional size of icon
* @param [opt.cluster] {object} { weight:{icon,size}, weight:{icon,size},... }
* @param [opt.cluster.icon] {string} png/jpg/svg file to represent group of pois. @ as first character indicates a file from this package. Anchor will be middle of icon
* @param [opt.cluster.size] {number} size of icon
* @param {function} cb callback to be called if click on item. Format cb(event, coord, payload, weigth).
* `coord` is coord of icon
* `payload` is payload associated to point.
* `weight` is number of points aggregated, when clicking on a cluster icon, 1 if single point
*
* @return {H.map.layer.ObjectLayer} layer created
*
* @example
* ```js
* let pois = [[48.8,2.3,"Hello world"],[48.5,2.4,"How are you"],[45.2,2.93,"Very well"]];
*
* hm.cluster(pois);
*
* // with more graphic options and callback defined
* let opt = {
* noise: {
* icon: "mcdo.png",
* size: 12
* },
* cluster: {
* 200: {
* icon: "@svg/cluster_red.svg",
* size: 64
* },
* 75: {
* icon: "@svg/cluster_orange.svg",
* size: 52
* },
* 2: {
* icon: "@svg/cluster_green.svg",
* size: 40
* }
* }
* };
* hm.cluster(pois, opt,
* (event, coordinate, data, weight) => {
* if (data)
* console.log("click on point ", data);
* else
* console.log("click on cluster with weight", weight);
* });
* ```
*/
async function cluster(coords, opt, cb = null) {
let dataPoints = [];
map = m.getMap();
let _home = cm.getHome();
let settings = {
eps: 64,
minZoom: 1, // min zoom
maxZoom: 24, // max zoom
noise: {
icon: _home + "svg/bluedot.svg",
size: 16
},
cluster: {
200: {
icon: _home + "svg/cluster_red.svg",
color: "#B50015",
size: 64
},
75: {
icon: _home + "svg/cluster_orange.svg",
color: "#FF6900",
size: 48
},
2: {
icon: _home + "svg/cluster_green.svg",
color: "#7BD30A",
size: 40
}
}
};
if (opt)
Object.assign(settings, opt);
let useTheme = true; // do we use our own theme ?
if (!opt || (opt && !opt.noise && !opt.cluster))
useTheme = false;
coords.forEach(coord => {
// use op_weight of 1 for each coord
// provides all coord as data
let dp = new H.clustering.DataPoint(coord[0], coord[1], 1, coord);
dataPoints.push(dp);
});
let minWeight = 2; // minimum weight by default
if (useTheme) {
// creating icon for noise (individual point)
let icon = settings.noise.icon;
if (icon[0] == "@") // to indicate local
icon = cm.getHome() + icon.substr(1);
let iconOpt = null;
if (settings.noise.size)
iconOpt = {
size: {
w: settings.noise.size,
h: settings.noise.size
}
};
iconNoise = new H.map.Icon(icon, iconOpt);
// get list of weight
let weightOrder = Object.keys(settings.cluster).sort(function (a, b) {
return b - a;
});
// minweight is the smallest weight
minWeight = weightOrder[weightOrder.length - 1];
let promises = [];
clusterStyle = weightOrder.map((weight) => {
let size = settings.cluster[weight].size;
let icon = settings.cluster[weight].icon;
if (icon[0] == "@") // to indicate local
icon = cm.getHome() + icon.substr(1);
let p = loadIconFile(icon, size, size);
promises.push(p);
let entry = {
weight: parseInt(weight),
icon: icon
};
return entry;
});
// wait for all promises to be resolved
const result = await Promise.all(promises);
// associated to each entry of clusterstyle
result.forEach((imageData, i) => {
clusterStyle[i].imageData = imageData;
});
}
let optProvider = {
clusteringOptions: {
// Maximum radius of the neighborhood
eps: settings.eps,
// minimum weight of points required to form a cluster
minWeight: minWeight
},
min: settings.minZoom, // min zoom
max: settings.maxZoom // max zoom
};
// if we use our own theme
if (useTheme)
optProvider.theme = {
getClusterPresentation: getClusterPresentation,
getNoisePresentation: getNoisePresentation
};
// create cluster provider
clusteredDataProvider = new H.clustering.Provider(dataPoints, optProvider);
// Create a layer that includes the data provider and its data points:
clusterLayer = new H.map.layer.ObjectLayer(clusteredDataProvider);
// Add the layer to the map:
map.addLayer(clusterLayer);
// layer is visible by default
_visible = true;
// if a callback is defined, add event listener
if (cb) {
clusteredDataProvider.addEventListener("tap", function (ev) {
// Log data bound to the marker that has been tapped:
let data = ev.target.getData();
let coord = map.screenToGeo(ev.currentPointer.viewportX, ev.currentPointer.viewportY);
let isCluster = data.isCluster();
if (isCluster) {
let weigth = data.getWeight();
cb(ev, m.coordO2A(coord), null, weigth);
} else {
let userData = data.getData(); // lat,lng, payload
cb(ev, m.coordO2A(coord), userData[2], 1);
}
});
}
return clusterLayer;
}
// this function creates the icon for a cluster
function getClusterPresentation(cluster) {
// building data object which will be returned when clicking on the icon
let data = {};
data.isCluster = () => {
return true;
}; // so we know it is a cluster
let weight = cluster.getWeight();
data.getWeight = () => {
return weight;
}; // number of individual item clustered together
// let's find the relevant color and size
let entry = clusterStyle.find(elt => (weight >= elt.weight));
let imageData = entry.imageData;
let icon = buildClusterIcon(imageData, "" + weight);
// create a marker for the Cluster
let min = cluster.getMinZoom();
let max = cluster.getMaxZoom();
let clusterMarker = new H.map.Marker(cluster.getPosition(), {
// to show it correctly at certain zoom levels:
min: min,
max: max,
icon: icon,
});
// Link data from the from the cluster to the marker,
// to make it accessible on callback
clusterMarker.setData(data);
return clusterMarker;
}
// function to represent a single item
function getNoisePresentation(noisePoint) {
// data to be sent on callback
const data = {
getData: () => {
return noisePoint.getData();
},
isCluster: () => {
return false;
},
getWeight: () => {
return 1;
}
};
// Create a marker for the noisePoint
var noiseMarker = new H.map.Marker(noisePoint.getPosition(), {
// Use min zoom from a noise point
// to show it correctly at certain zoom levels:
min: noisePoint.getMinZoom(),
icon: iconNoise
});
// Link a data from the point to the marker
// to make it accessible on callback
noiseMarker.setData(data);
return noiseMarker;
}
/**
* load a file into a canvas
* @ignore
* @param {String} url of png,jpg,svg file
* @param {Number} width for svg, define width
* @param {number} height for svg, define height
*/
function loadIconFile(file, width = null, height = null) {
return new Promise(
(resolve) => {
var newImg = new Image;
newImg.onload = function () {
let width = newImg.width;
let height = newImg.height;
// copy icon into a canvas
let src = document.createElement("canvas");
src.width = width;
src.height = height;
let ctx = src.getContext("2d");
// copy image into canvas cluster
ctx.drawImage(newImg, 0, 0, width, height);
let imageData = ctx.getImageData(0, 0, width, height);
resolve(imageData);
};
newImg.crossOrigin = "Anonymous"; // useful.. ?
if (width) newImg.width = width;
if (height) newImg.height = height;
newImg.src = file;
}
);
}
/**
* Build an icon by copying imageData and adding text
* @ignore
* @param {ImageData} imgData from canvas.getImageData
* @param {String} text text to write
*/
function buildClusterIcon(imgData, text) {
const canvas = document.createElement("canvas");
canvas.width = imgData.width;
canvas.height = imgData.height;
let ctx = canvas.getContext("2d");
const fontSize = 12;
ctx.font = "bold " + fontSize + "px Arial";
ctx.fillStyle = "white";
ctx.textAlign = "center";
ctx.putImageData(imgData, 0, 0);
ctx.fillText(text, canvas.width / 2, (canvas.height + fontSize) / 2 - 2);
return new H.map.Icon(canvas, {
anchor: {
x: canvas.width / 2,
y: canvas.height / 2
}
});
}
/**
* Hide cluster layer
* @alias hm:clusterHide
*/
function clusterHide() {
if (!_visible || !clusterLayer)
return;
map.removeLayer(clusterLayer);
_visible = false;
}
/**
* Show Cluster layer
* @alias hm:clusterShow
*/
function clusterShow() {
if (_visible || !clusterLayer)
return;
map.addLayer(clusterLayer);
_visible = true;
}
module.exports = {
cluster: cluster,
clusterShow: clusterShow,
clusterHide: clusterHide
};