Add imageRatio option for VectorImage layers

test/spec/ol/renderer/canvas/vectorimage.test.js

@@ -1,6 +1,9 @@
 import VectorImageLayer from '../../../../../src/ol/layer/VectorImage.js';
 import VectorSource from '../../../../../src/ol/source/Vector.js';
 import CanvasVectorImageLayerRenderer from '../../../../../src/ol/renderer/canvas/VectorImageLayer.js';
+import {get as getProjection} from '../../../../../src/ol/proj.js';
+import {scaleFromCenter} from '../../../../../src/ol/extent.js';
+
 
 describe('ol/renderer/canvas/VectorImageLayer', function() {
 
@@ -18,4 +21,36 @@ describe('ol/renderer/canvas/VectorImageLayer', function() {
 
   });
 
+  describe('#prepareFrame', function() {
+
+    it('sets correct extent with imageRatio = 2', function() {
+      const layer = new VectorImageLayer({
+        imageRatio: 2,
+        source: new VectorSource()
+      });
+      const renderer = new CanvasVectorImageLayerRenderer(layer);
+      const projection = getProjection('EPSG:3857');
+      const projExtent = projection.getExtent();
+      const extent = [
+        projExtent[0] - 10000, -10000, projExtent[0] + 10000, 10000
+      ];
+      const frameState = {
+        extent: extent,
+        skippedFeatureUids: {},
+        viewHints: [],
+        viewState: {
+          projection: projection,
+          resolution: 1,
+          rotation: 0
+        }
+      };
+      renderer.prepareFrame(frameState, {});
+      const expected = renderer.image_.getExtent();
+
+      scaleFromCenter(extent, 2);
+
+      expect(expected).to.eql(extent);
+    });
+  });
+
 });