原文链接及内容
此示例使用ol/layer/VectorImage在交互和动画过程中实现更快的渲染，但代价是渲染精度较低。
main.js代码如下：
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| import GeoJSON from 'ol/format/GeoJSON.js';
import Map from 'ol/Map.js';
import VectorImageLayer from 'ol/layer/VectorImage.js';
import VectorLayer from 'ol/layer/Vector.js';
import VectorSource from 'ol/source/Vector.js';
import View from 'ol/View.js';
import {Fill, Stroke, Style} from 'ol/style.js';
const style = new Style({
fill: new Fill({
color: '#eeeeee',
}),
});
const vectorLayer = new VectorImageLayer({
background: '#1a2b39',
imageRatio: 2,
source: new VectorSource({
url: 'https://openlayers.org/data/vector/ecoregions.json',
format: new GeoJSON(),
}),
style: function (feature) {
const color = feature.get('COLOR') || '#eeeeee';
style.getFill().setColor(color);
return style;
},
});
const map = new Map({
layers: [vectorLayer],
target: 'map',
view: new View({
center: [0, 0],
zoom: 1,
}),
});
const featureOverlay = new VectorLayer({
source: new VectorSource(),
map: map,
style: new Style({
stroke: new Stroke({
color: 'rgba(255, 255, 255, 0.7)',
width: 2,
}),
}),
});
let highlight;
const displayFeatureInfo = function (pixel) {
const feature = map.forEachFeatureAtPixel(pixel, function (feature) {
return feature;
});
const info = document.getElementById('info');
if (feature) {
info.innerHTML = feature.get('ECO_NAME') || ' ';
} else {
info.innerHTML = ' ';
}
if (feature !== highlight) {
if (highlight) {
featureOverlay.getSource().removeFeature(highlight);
}
if (feature) {
featureOverlay.getSource().addFeature(feature);
}
highlight = feature;
}
};
map.on('pointermove', function (evt) {
if (evt.dragging) {
return;
}
const pixel = map.getEventPixel(evt.originalEvent);
displayFeatureInfo(pixel);
});
map.on('click', function (evt) {
displayFeatureInfo(evt.pixel);
});
|
界面布局文件index.html代码如下：
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| <!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Vector Image Layer</title>
<link rel="stylesheet" href="node_modules/ol/ol.css">
<style>
.map {
width: 100%;
height: 400px;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<div id="info"> </div>
<script src="https://cdn.jsdelivr.net/npm/elm-pep@1.0.6/dist/elm-pep.js"></script>
<script type="module" src="main.js"></script>
</body>
</html>
|
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