Files
openlayers/examples/offscreen-canvas-tiles.js
2020-03-23 12:46:20 +01:00

64 lines
1.7 KiB
JavaScript

import Map from '../src/ol/Map.js';
import View from '../src/ol/View.js';
import Layer from '../src/ol/layer/Layer.js';
//eslint-disable-next-line
import Worker from 'worker-loader!./mvtlayer.worker.js';
const mvtLayerWorker = new Worker();
function getCircularReplacer() {
const seen = new WeakSet();
return function(key, value) {
if (typeof value === 'object' && value !== null) {
if (seen.has(value)) {
return '[circular]';
}
seen.add(value);
}
return value;
};
}
let container, canvas;
const map = new Map({
layers: [
new Layer({
render: function(frameState) {
if (!container) {
container = document.createElement('div');
container.style.position = 'absolute';
container.style.width = '100%';
container.style.height = '100%';
canvas = document.createElement('canvas');
canvas.style.position = 'absolute';
canvas.style.left = '0';
canvas.style.transformOrigin = 'top left';
container.appendChild(canvas);
const offscreen = canvas.transferControlToOffscreen();
mvtLayerWorker.postMessage({
canvas: offscreen
}, [offscreen]);
}
mvtLayerWorker.postMessage({
frameState: JSON.parse(JSON.stringify(frameState, getCircularReplacer()))
});
return container;
}
})
],
target: 'map',
view: new View({
center: [0, 0],
zoom: 2
})
});
mvtLayerWorker.addEventListener('message', message => {
if (message.data.type === 'render') {
map.render();
} else if (canvas && message.data.type === 'transform-opacity') {
canvas.style.transform = message.data.transform;
canvas.style.opacity = message.data.opacity;
}
});