ol/source/Cluster.js

父类

ol/source/Cluster-Cluster

主要功能

聚类点数据源。

参数：VectorSource({})

方法

/**
* @module ol/source/Cluster
*/
import EventType from '../events/EventType.js';
import Feature from '../Feature.js';
import GeometryType from '../geom/GeometryType.js';
import Point from '../geom/Point.js';
import VectorSource from './Vector.js';
import {add as addCoordinate, scale as scaleCoordinate} from '../coordinate.js';
import {assert} from '../asserts.js';
import {
buffer,
createEmpty,
createOrUpdateFromCoordinate,
getCenter,
} from '../extent.js';
import {getUid} from '../util.js';
/**
* @typedef {Object} Options
* @property {import("./Source.js").AttributionLike} [attributions] Attributions.
* @property {number} [distance=20] Distance in pixels within which features will
* be clustered together.
* @property {number} [minDistance=0] Minimum distance in pixels between clusters.
* Will be capped at the configured distance.
* By default no minimum distance is guaranteed. This config can be used to avoid
* overlapping icons. As a tradoff, the cluster feature's position will no longer be
* the center of all its features.
* @property {function(Feature):Point} [geometryFunction]
* Function that takes an {@link module:ol/Feature} as argument and returns an
* {@link module:ol/geom/Point} as cluster calculation point for the feature. When a
* feature should not be considered for clustering, the function should return
* `null`. The default, which works when the underlying source contains point
* features only, is
* ```js
* function(feature) {
*
return feature.getGeometry();
* }
* ```
* See {@link module:ol/geom/Polygon~Polygon#getInteriorPoint} for a way to get a cluster
* calculation point for polygons.
* @property {function(Point, Array<Feature>):Feature} [createCluster]
* Function that takes the cluster's center {@link module:ol/geom/Point} and an array
* of {@link module:ol/Feature} included in this cluster. Must return a
* {@link module:ol/Feature} that will be used to render. Default implementation is:
* ```js
* function(point, features) {
*
return new Feature({
*
geometry: point,
*
features: features
*
});
* }
* ```
* @property {VectorSource} [source] Source.
* @property {boolean} [wrapX=true] Whether to wrap the world horizontally.
*/
/**
* @classdesc
* Layer source to cluster vector data. Works out of the box with point
* geometries. For other geometry types, or if not all geometries should be
* considered for clustering, a custom `geometryFunction` can be defined.
*
* If the instance is disposed without also disposing the underlying
* source `setSource(null)` has to be called to remove the listener reference
* from the wrapped source.
* @api
*/
class Cluster extends VectorSource {
/**
* @param {Options} options Cluster options.
*/
constructor(options) {
super({
attributions: options.attributions,
wrapX: options.wrapX,
});
/**
* @type {number|undefined}
* @protected
*/
this.resolution = undefined;
/**
* @type {number}
* @protected
*/
this.distance = options.distance !== undefined ? options.distance : 20;
/**
* @type {number}
* @protected
*/
this.minDistance = options.minDistance || 0;
/**
* @type {number}
* @protected
*/
this.interpolationRatio = 0;
/**
* @type {Array<Feature>}
* @protected
*/
this.features = [];
/**
* @param {Feature} feature Feature.
* @return {Point} Cluster calculation point.
* @protected
*/
this.geometryFunction =
options.geometryFunction ||
function (feature) {
const geometry = feature.getGeometry();
assert(geometry.getType() == GeometryType.POINT, 10); // The default `geometryFunction` can only handle `Point` geometries
return geometry;
};
/**
* @type {function(Point, Array<Feature>):Feature}
* @private
*/
this.createCustomCluster_ = options.createCluster;
/**
* @type {VectorSource}
* @protected
*/
this.source = null;
this.boundRefresh_ = this.refresh.bind(this);
this.updateDistance(this.distance, this.minDistance);
this.setSource(options.source || null);
}
/**
* Remove all features from the source.
* @param {boolean} [opt_fast] Skip dispatching of {@link module:ol/source/Vector.VectorSourceEvent#removefeature} events.
* @api
*/
clear(opt_fast) {
this.features.length = 0;
super.clear(opt_fast);
}
/**
* Get the distance in pixels between clusters.
* @return {number} Distance.
* @api
*/
getDistance() {
return this.distance;
}
/**
* Get a reference to the wrapped source.
* @return {VectorSource} Source.
* @api
*/
getSource() {
return this.source;
}
/**
* @param {import("../extent.js").Extent} extent Extent.
* @param {number} resolution Resolution.
* @param {import("../proj/Projection.js").default} projection Projection.
*/
loadFeatures(extent, resolution, projection) {
this.source.loadFeatures(extent, resolution, projection);
if (resolution !== this.resolution) {
this.resolution = resolution;
this.refresh();
}
}
/**
* Set the distance within which features will be clusterd together.
* @param {number} distance The distance in pixels.
* @api
*/
setDistance(distance) {
this.updateDistance(distance, this.minDistance);
}
/**
* Set the minimum distance between clusters. Will be capped at the
* configured distance.
* @param {number} minDistance The minimum distance in pixels.
* @api
*/
setMinDistance(minDistance) {
this.updateDistance(this.distance, minDistance);
}
/**
* The configured minimum distance between clusters.
* @return {number} The minimum distance in pixels.
* @api
*/
getMinDistance() {
return this.minDistance;
}
/**
* Replace the wrapped source.
* @param {VectorSource} source The new source for this instance.
* @api
*/
setSource(source) {
if (this.source) {
this.source.removeEventListener(EventType.CHANGE, this.boundRefresh_);
}
this.source = source;
if (source) {
source.addEventListener(EventType.CHANGE, this.boundRefresh_);
}
this.refresh();
}
/**
* Handle the source changing.
*/
refresh() {
this.clear();
this.cluster();
this.addFeatures(this.features);
}
/**
* Update the distances and refresh the source if necessary.
* @param {number} distance The new distance.
* @param {number} minDistance The new minimum distance.
*/
updateDistance(distance, minDistance) {
const ratio =
distance === 0 ? 0 : Math.min(minDistance, distance) / distance;
const changed =
distance !== this.distance || this.interpolationRatio !== ratio;
this.distance = distance;
this.minDistance = minDistance;
this.interpolationRatio = ratio;
if (changed) {
this.refresh();
}
}
/**
* @protected
*/
cluster() {
if (this.resolution === undefined || !this.source) {
return;
}
const extent = createEmpty();
const mapDistance = this.distance * this.resolution;
const features = this.source.getFeatures();
/** @type {Object<string, true>} */
const clustered = {};
for (let i = 0, ii = features.length; i < ii; i++) {
const feature = features[i];
if (!(getUid(feature) in clustered)) {
const geometry = this.geometryFunction(feature);
if (geometry) {
const coordinates = geometry.getCoordinates();
createOrUpdateFromCoordinate(coordinates, extent);
buffer(extent, mapDistance, extent);
const neighbors = this.source
.getFeaturesInExtent(extent)
.filter(function (neighbor) {
const uid = getUid(neighbor);
if (uid in clustered) {
return false;
}
clustered[uid] = true;
return true;
});
this.features.push(this.createCluster(neighbors, extent));
}
}
}
}
/**
* @param {Array<Feature>} features Features
* @param {import("../extent.js").Extent} extent The searched extent for these features.
* @return {Feature} The cluster feature.
* @protected
*/
createCluster(features, extent) {
const centroid = [0, 0];
for (let i = features.length - 1; i >= 0; --i) {
const geometry = this.geometryFunction(features[i]);
if (geometry) {
addCoordinate(centroid, geometry.getCoordinates());
} else {
features.splice(i, 1);
}
}
scaleCoordinate(centroid, 1 / features.length);
const searchCenter = getCenter(extent);
const ratio = this.interpolationRatio;
const geometry = new Point([
centroid[0] * (1 - ratio) + searchCenter[0] * ratio,
centroid[1] * (1 - ratio) + searchCenter[1] * ratio,
]);
if (this.createCustomCluster_) {
return this.createCustomCluster_(geometry, features);
} else {
return new Feature({
geometry,
features,
});
}
}
}
export default Cluster;

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