Files
openlayers/examples/export-map.js
2020-02-14 19:49:17 +00:00

57 lines
1.9 KiB
JavaScript

import Map from '../src/ol/Map.js';
import View from '../src/ol/View.js';
import GeoJSON from '../src/ol/format/GeoJSON.js';
import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
import {OSM, Vector as VectorSource} from '../src/ol/source.js';
const map = new Map({
layers: [
new TileLayer({
source: new OSM()
}),
new VectorLayer({
source: new VectorSource({
url: 'data/geojson/countries.geojson',
format: new GeoJSON()
}),
opacity: 0.5
})
],
target: 'map',
view: new View({
center: [0, 0],
zoom: 2
})
});
document.getElementById('export-png').addEventListener('click', function() {
map.once('rendercomplete', function() {
const mapCanvas = document.createElement('canvas');
const size = map.getSize();
mapCanvas.width = size[0];
mapCanvas.height = size[1];
const mapContext = mapCanvas.getContext('2d');
Array.prototype.forEach.call(document.querySelectorAll('.ol-layer canvas'), function(canvas) {
if (canvas.width > 0) {
const opacity = canvas.parentNode.style.opacity;
mapContext.globalAlpha = opacity === '' ? 1 : Number(opacity);
const transform = canvas.style.transform;
// Get the transform parameters from the style's transform matrix
const matrix = transform.match(/^matrix\(([^\(]*)\)$/)[1].split(',').map(Number);
// Apply the transform to the export map context
CanvasRenderingContext2D.prototype.setTransform.apply(mapContext, matrix);
mapContext.drawImage(canvas, 0, 0);
}
});
if (navigator.msSaveBlob) {
// link download attribuute does not work on MS browsers
navigator.msSaveBlob(mapCanvas.msToBlob(), 'map.png');
} else {
const link = document.getElementById('image-download');
link.href = mapCanvas.toDataURL();
link.click();
}
});
map.renderSync();
});