Get pixel data

test/browser/spec/ol/layer/Image.test.js

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+import ImageLayer from '../../../../../src/ol/layer/Image.js';
+import Map from '../../../../../src/ol/Map.js';
+import Static from '../../../../../src/ol/source/ImageStatic.js';
+import View from '../../../../../src/ol/View.js';
+import {Projection} from '../../../../../src/ol/proj.js';
+
+describe('ol/layer/Image', () => {
+  describe('getData()', () => {
+    let map, target, layer;
+
+    beforeEach((done) => {
+      const projection = new Projection({
+        code: 'custom-image',
+        units: 'pixels',
+        extent: [0, 0, 200, 200],
+      });
+
+      target = document.createElement('div');
+      target.style.width = '100px';
+      target.style.height = '100px';
+      document.body.appendChild(target);
+
+      const imageExtent = [0, 0, 20, 20];
+      const source = new Static({
+        url: 'spec/ol/data/dot.png',
+        projection: projection,
+        imageExtent: imageExtent,
+      });
+
+      layer = new ImageLayer({
+        source: source,
+        extent: imageExtent,
+      });
+
+      map = new Map({
+        pixelRatio: 1,
+        target: target,
+        layers: [layer],
+        view: new View({
+          projection: projection,
+          center: [10, 10],
+          zoom: 1,
+          maxZoom: 8,
+        }),
+      });
+      map.once('rendercomplete', () => {
+        done();
+      });
+    });
+
+    afterEach(() => {
+      map.setTarget(null);
+      document.body.removeChild(target);
+    });
+
+    it('should not detect pixels outside of the layer extent', () => {
+      map.renderSync();
+      const pixel = [10, 10];
+      const data = layer.getData(pixel);
+      expect(data).to.be(null);
+    });
+
+    it('should detect pixels in the layer extent', () => {
+      map.renderSync();
+      const pixel = [50, 50];
+      const data = layer.getData(pixel);
+      expect(data).to.be.a(Uint8ClampedArray);
+      expect(data.length).to.be(4);
+      expect(data[0]).to.be(255);
+      expect(data[1]).to.be(255);
+      expect(data[2]).to.be(255);
+      expect(data[3]).to.be(255);
+    });
+  });
+});