Files
openlayers/examples/canvas-gradient-pattern.js
Tim Schaub 054af09032 Make code prettier
This updates ESLint and our shared eslint-config-openlayers to use Prettier.  Most formatting changes were automatically applied with this:

    npm run lint -- --fix

A few manual changes were required:

 * In `examples/offscreen-canvas.js`, the `//eslint-disable-line` comment needed to be moved to the appropriate line to disable the error about the `'worker-loader!./offscreen-canvas.worker.js'` import.
 * In `examples/webpack/exapmle-builder.js`, spaces could not be added after a couple `function`s for some reason.  While editing this, I reworked `ExampleBuilder` to be a class.
 * In `src/ol/format/WMSGetFeatureInfo.js`, the `// @ts-ignore` comment needed to be moved down one line so it applied to the `parsersNS` argument.
2020-04-06 12:54:09 -06:00

91 lines
2.7 KiB
JavaScript

import GeoJSON from '../src/ol/format/GeoJSON.js';
import Map from '../src/ol/Map.js';
import VectorLayer from '../src/ol/layer/Vector.js';
import VectorSource from '../src/ol/source/Vector.js';
import View from '../src/ol/View.js';
import {DEVICE_PIXEL_RATIO} from '../src/ol/has.js';
import {Fill, Stroke, Style} from '../src/ol/style.js';
import {fromLonLat} from '../src/ol/proj.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 {import("../src/ol/Feature.js").default} feature The feature to style.
* @return {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,
}),
});