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| import Feature from 'ol/Feature.js';
import Map from 'ol/Map.js';
import VectorLayer from 'ol/layer/Vector.js';
import VectorSource from 'ol/source/Vector.js';
import View from 'ol/View.js';
import {Circle as CircleStyle, Fill, Stroke, Style} from 'ol/style.js';
import {LineString, Point} from 'ol/geom.js';
import {getVectorContext} from 'ol/render.js';
const count = 20000;
const features = new Array(count);
const e = 18000000;
for (let i = 0; i < count; ++i) {
features[i] = new Feature({
'geometry': new Point([
2 * e * Math.random() - e,
2 * e * Math.random() - e,
]),
'i': i,
'size': i % 2 ? 10 : 20,
});
}
const styles = {
'10': new Style({
image: new CircleStyle({
radius: 5,
fill: new Fill({color: '#666666'}),
stroke: new Stroke({color: '#bada55', width: 1}),
}),
}),
'20': new Style({
image: new CircleStyle({
radius: 10,
fill: new Fill({color: '#666666'}),
stroke: new Stroke({color: '#bada55', width: 1}),
}),
}),
};
const vectorSource = new VectorSource({
features: features,
wrapX: false,
});
const vector = new VectorLayer({
source: vectorSource,
style: function (feature) {
return styles[feature.get('size')];
},
});
const map = new Map({
layers: [vector],
target: document.getElementById('map'),
view: new View({
center: [0, 0],
zoom: 2,
}),
});
let point = null;
let line = null;
const displaySnap = function (coordinate) {
const closestFeature = vectorSource.getClosestFeatureToCoordinate(coordinate);
if (closestFeature === null) {
point = null;
line = null;
} else {
const geometry = closestFeature.getGeometry();
const closestPoint = geometry.getClosestPoint(coordinate);
if (point === null) {
point = new Point(closestPoint);
} else {
point.setCoordinates(closestPoint);
}
if (line === null) {
line = new LineString([coordinate, closestPoint]);
} else {
line.setCoordinates([coordinate, closestPoint]);
}
}
map.render();
};
map.on('pointermove', function (evt) {
if (evt.dragging) {
return;
}
const coordinate = map.getEventCoordinate(evt.originalEvent);
displaySnap(coordinate);
});
map.on('click', function (evt) {
displaySnap(evt.coordinate);
});
const stroke = new Stroke({
color: 'rgba(255,255,0,0.9)',
width: 3,
});
const style = new Style({
stroke: stroke,
image: new CircleStyle({
radius: 10,
stroke: stroke,
}),
});
vector.on('postrender', function (evt) {
const vectorContext = getVectorContext(evt);
vectorContext.setStyle(style);
if (point !== null) {
vectorContext.drawGeometry(point);
}
if (line !== null) {
vectorContext.drawGeometry(line);
}
});
map.on('pointermove', function (evt) {
if (evt.dragging) {
return;
}
const pixel = map.getEventPixel(evt.originalEvent);
const hit = map.hasFeatureAtPixel(pixel);
if (hit) {
map.getTarget().style.cursor = 'pointer';
} else {
map.getTarget().style.cursor = '';
}
});
|
)
