93 lines
2.7 KiB
JavaScript
93 lines
2.7 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 {DEVICE_PIXEL_RATIO} from '../src/ol/has.js';
|
|
import VectorLayer from '../src/ol/layer/Vector.js';
|
|
import {fromLonLat} from '../src/ol/proj.js';
|
|
import VectorSource from '../src/ol/source/Vector.js';
|
|
import {Fill, Stroke, Style} from '../src/ol/style.js';
|
|
|
|
const canvas = document.createElement('canvas');
|
|
const context = canvas.getContext('2d');
|
|
|
|
// Gradient and pattern are in canvas pixel space, so we adjust for the
|
|
// renderer's pixel ratio
|
|
const pixelRatio = DEVICE_PIXEL_RATIO;
|
|
|
|
// Generate a rainbow gradient
|
|
const gradient = (function() {
|
|
const grad = context.createLinearGradient(0, 0, 512 * pixelRatio, 0);
|
|
grad.addColorStop(0, 'red');
|
|
grad.addColorStop(1 / 6, 'orange');
|
|
grad.addColorStop(2 / 6, 'yellow');
|
|
grad.addColorStop(3 / 6, 'green');
|
|
grad.addColorStop(4 / 6, 'aqua');
|
|
grad.addColorStop(5 / 6, 'blue');
|
|
grad.addColorStop(1, 'purple');
|
|
return grad;
|
|
})();
|
|
|
|
// Generate a canvasPattern with two circles on white background
|
|
const pattern = (function() {
|
|
canvas.width = 8 * pixelRatio;
|
|
canvas.height = 8 * pixelRatio;
|
|
// white background
|
|
context.fillStyle = 'white';
|
|
context.fillRect(0, 0, canvas.width, canvas.height);
|
|
// outer circle
|
|
context.fillStyle = 'rgba(102, 0, 102, 0.5)';
|
|
context.beginPath();
|
|
context.arc(4 * pixelRatio, 4 * pixelRatio, 3 * pixelRatio, 0, 2 * Math.PI);
|
|
context.fill();
|
|
// inner circle
|
|
context.fillStyle = 'rgb(55, 0, 170)';
|
|
context.beginPath();
|
|
context.arc(4 * pixelRatio, 4 * pixelRatio, 1.5 * pixelRatio, 0, 2 * Math.PI);
|
|
context.fill();
|
|
return context.createPattern(canvas, 'repeat');
|
|
}());
|
|
|
|
// Generate style for gradient or pattern fill
|
|
const fill = new Fill();
|
|
const style = new Style({
|
|
fill: fill,
|
|
stroke: new Stroke({
|
|
color: '#333',
|
|
width: 2
|
|
})
|
|
});
|
|
|
|
/**
|
|
* The styling function for the vector layer, will return an array of styles
|
|
* which either contains the aboove gradient or pattern.
|
|
*
|
|
* @param {module:ol/Feature~Feature} feature The feature to style.
|
|
* @return {module:ol/style/Style} The style to use for the feature.
|
|
*/
|
|
const getStackedStyle = function(feature) {
|
|
const id = feature.getId();
|
|
fill.setColor(id > 'J' ? gradient : pattern);
|
|
return style;
|
|
};
|
|
|
|
// Create a vector layer that makes use of the style function above…
|
|
const vectorLayer = new VectorLayer({
|
|
source: new VectorSource({
|
|
url: 'data/geojson/countries.geojson',
|
|
format: new GeoJSON()
|
|
}),
|
|
style: getStackedStyle
|
|
});
|
|
|
|
// … finally create a map with that layer.
|
|
const map = new Map({
|
|
layers: [
|
|
vectorLayer
|
|
],
|
|
target: 'map',
|
|
view: new View({
|
|
center: fromLonLat([16, 48]),
|
|
zoom: 3
|
|
})
|
|
});
|