openlayers:实现图层裁剪
图层裁剪示例
main.js
import Map from 'ol/Map.js';
import OSM from 'ol/source/OSM.js';
import TileLayer from 'ol/layer/Tile.js';
import View from 'ol/View.js';
const osm = new TileLayer({
source: new OSM(),
});
const map = new Map({
layers: [osm],
target: 'map',
view: new View({
center: [0, 0],
zoom: 2,
}),
});
osm.on('prerender', function (event) {
const ctx = event.context;
// calculate the pixel ratio and rotation of the canvas
const matrix = event.inversePixelTransform;
const canvasPixelRatio = Math.sqrt(
matrix[0] * matrix[0] + matrix[1] * matrix[1]
);
const canvasRotation = -Math.atan2(matrix[1], matrix[0]);