Files
openlayers/examples/offscreen-canvas-tiles.js
2020-03-23 12:46:21 +01:00

97 lines
3.2 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';
import {compose, create} from '../src/ol/transform.js';
import {createTransformString} from '../src/ol/render/canvas.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, transformContainer, canvas, workerFrameState, mainThreadFrameState;
function updateContainerTransform() {
if (workerFrameState) {
const viewState = mainThreadFrameState.viewState;
const renderedViewState = workerFrameState.viewState;
const center = viewState.center;
const resolution = viewState.resolution;
const rotation = viewState.rotation;
const renderedCenter = renderedViewState.center;
const renderedResolution = renderedViewState.resolution;
const renderedRotation = renderedViewState.rotation;
const transform = compose(create(),
(renderedCenter[0] - center[0]) / resolution,
(center[1] - renderedCenter[1]) / resolution,
renderedResolution / resolution, renderedResolution / resolution,
rotation - renderedRotation,
0, 0);
transformContainer.style.transform = createTransformString(transform);
}
}
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%';
transformContainer = document.createElement('div');
transformContainer.style.position = 'absolute';
transformContainer.style.width = '100%';
transformContainer.style.height = '100%';
container.appendChild(transformContainer);
canvas = document.createElement('canvas');
canvas.style.position = 'absolute';
canvas.style.left = '0';
canvas.style.transformOrigin = 'top left';
transformContainer.appendChild(canvas);
}
mainThreadFrameState = frameState;
updateContainerTransform();
mvtLayerWorker.postMessage({
frameState: JSON.parse(JSON.stringify(frameState, getCircularReplacer()))
});
return container;
}
})
],
target: 'map',
view: new View({
center: [0, 0],
zoom: 2
})
});
mvtLayerWorker.addEventListener('message', function(message) {
if (message.data.type === 'request-render') {
map.render();
} else if (canvas && message.data.type === 'rendered') {
transformContainer.style.transform = '';
const imageData = message.data.imageData;
canvas.width = imageData.width;
canvas.height = imageData.height;
canvas.getContext('2d').drawImage(imageData, 0, 0);
canvas.style.opacity = message.data.opacity;
canvas.style.transform = message.data.transform;
workerFrameState = message.data.frameState;
updateContainerTransform();
}
});