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| import KML from 'ol/format/KML.js';
import Map from 'ol/Map.js';
import View from 'ol/View.js';
import {
Circle as CircleStyle,
Fill,
RegularShape,
Stroke,
Style,
Text,
} from 'ol/style.js';
import {Cluster, Stamen, Vector as VectorSource} from 'ol/source.js';
import {
Select,
defaults as defaultInteractions,
} from 'ol/interaction.js';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer.js';
import {createEmpty, extend, getHeight, getWidth} from 'ol/extent.js';
const earthquakeFill = new Fill({
color: 'rgba(255, 153, 0, 0.8)',
});
const earthquakeStroke = new Stroke({
color: 'rgba(255, 204, 0, 0.2)',
width: 1,
});
const textFill = new Fill({
color: '#fff',
});
const textStroke = new Stroke({
color: 'rgba(0, 0, 0, 0.6)',
width: 3,
});
const invisibleFill = new Fill({
color: 'rgba(255, 255, 255, 0.01)',
});
function createEarthquakeStyle(feature) {
const name = feature.get('name');
const magnitude = parseFloat(name.substr(2));
const radius = 5 + 20 * (magnitude - 5);
return new Style({
geometry: feature.getGeometry(),
image: new RegularShape({
radius1: radius,
radius2: 3,
points: 5,
angle: Math.PI,
fill: earthquakeFill,
stroke: earthquakeStroke,
}),
});
}
let maxFeatureCount;
let vector = null;
const calculateClusterInfo = function (resolution) {
maxFeatureCount = 0;
const features = vector.getSource().getFeatures();
let feature, radius;
for (let i = features.length - 1; i >= 0; --i) {
feature = features[i];
const originalFeatures = feature.get('features');
const extent = createEmpty();
let j, jj;
for (j = 0, jj = originalFeatures.length; j < jj; ++j) {
extend(extent, originalFeatures[j].getGeometry().getExtent());
}
maxFeatureCount = Math.max(maxFeatureCount, jj);
radius = (0.25 * (getWidth(extent) + getHeight(extent))) / resolution;
feature.set('radius', radius);
}
};
let currentResolution;
function styleFunction(feature, resolution) {
if (resolution != currentResolution) {
calculateClusterInfo(resolution);
currentResolution = resolution;
}
let style;
const size = feature.get('features').length;
if (size > 1) {
style = new Style({
image: new CircleStyle({
radius: feature.get('radius'),
fill: new Fill({
color: [255, 153, 0, Math.min(0.8, 0.4 + size / maxFeatureCount)],
}),
}),
text: new Text({
text: size.toString(),
fill: textFill,
stroke: textStroke,
}),
});
} else {
const originalFeature = feature.get('features')[0];
style = createEarthquakeStyle(originalFeature);
}
return style;
}
function selectStyleFunction(feature) {
const styles = [
new Style({
image: new CircleStyle({
radius: feature.get('radius'),
fill: invisibleFill,
}),
}),
];
const originalFeatures = feature.get('features');
let originalFeature;
for (let i = originalFeatures.length - 1; i >= 0; --i) {
originalFeature = originalFeatures[i];
styles.push(createEarthquakeStyle(originalFeature));
}
return styles;
}
vector = new VectorLayer({
source: new Cluster({
distance: 40,
source: new VectorSource({
url: 'data/kml/2012_Earthquakes_Mag5.kml',
format: new KML({
extractStyles: false,
}),
}),
}),
style: styleFunction,
});
const raster = new TileLayer({
source: new Stamen({
layer: 'toner',
}),
});
const map = new Map({
layers: [raster, vector],
interactions: defaultInteractions().extend([
new Select({
condition: function (evt) {
return evt.type == 'pointermove' || evt.type == 'singleclick';
},
style: selectStyleFunction,
}),
]),
target: 'map',
view: new View({
center: [0, 0],
zoom: 2,
}),
});
|
)
