Support hitTolerance in forEachLayerAtPixel

src/ol/PluggableMap.js

@@ -612,29 +612,22 @@ PluggableMap.prototype.getFeaturesAtPixel = function(pixel, opt_options) {
  *     [R, G, B, A] pixel values (0 - 255) and will be `null` for layer types
  *     that do not currently support this argument. To stop detection, callback
  *     functions can return a truthy value.
- * @param {S=} opt_this Value to use as `this` when executing `callback`.
- * @param {(function(this: U, module:ol/layer/Layer): boolean)=} opt_layerFilter Layer
- *     filter function. The filter function will receive one argument, the
- *     {@link module:ol/layer/Layer layer-candidate} and it should return a boolean
- *     value. Only layers which are visible and for which this function returns
- *     `true` will be tested for features. By default, all visible layers will
- *     be tested.
- * @param {U=} opt_this2 Value to use as `this` when executing `layerFilter`.
+ * @param {module:ol/PluggableMap~AtPixelOptions=} opt_options Configuration options.
  * @return {T|undefined} Callback result, i.e. the return value of last
  * callback execution, or the first truthy callback return value.
- * @template S,T,U
+ * @template S,T
  * @api
  */
-PluggableMap.prototype.forEachLayerAtPixel = function(pixel, callback, opt_this, opt_layerFilter, opt_this2) {
+PluggableMap.prototype.forEachLayerAtPixel = function(pixel, callback, opt_options) {
   if (!this.frameState_) {
     return;
   }
-  const thisArg = opt_this !== undefined ? opt_this : null;
-  const layerFilter = opt_layerFilter !== undefined ? opt_layerFilter : TRUE;
-  const thisArg2 = opt_this2 !== undefined ? opt_this2 : null;
+  const options = opt_options || {};
+  const hitTolerance = options.hitTolerance !== undefined ?
+    opt_options.hitTolerance * this.frameState_.pixelRatio : 0;
+  const layerFilter = options.layerFilter || TRUE;
   return this.renderer_.forEachLayerAtPixel(
-    pixel, this.frameState_, callback, thisArg,
-    layerFilter, thisArg2);
+    pixel, this.frameState_, hitTolerance, callback, null, layerFilter, null);
 };
 
 

src/ol/renderer/Map.js

@@ -181,6 +181,7 @@ MapRenderer.prototype.forEachFeatureAtCoordinate = function(coordinate, frameSta
  * @abstract
  * @param {module:ol~Pixel} pixel Pixel.
  * @param {module:ol/PluggableMap~FrameState} frameState FrameState.
+ * @param {number} hitTolerance Hit tolerance in pixels.
  * @param {function(this: S, module:ol/layer/Layer, (Uint8ClampedArray|Uint8Array)): T} callback Layer
  *     callback.
  * @param {S} thisArg Value to use as `this` when executing `callback`.
@@ -192,7 +193,7 @@ MapRenderer.prototype.forEachFeatureAtCoordinate = function(coordinate, frameSta
  * @return {T|undefined} Callback result.
  * @template S,T,U
  */
-MapRenderer.prototype.forEachLayerAtPixel = function(pixel, frameState, callback, thisArg,
+MapRenderer.prototype.forEachLayerAtPixel = function(pixel, frameState, hitTolerance, callback, thisArg,
   layerFilter, thisArg2) {};
 
 

src/ol/renderer/canvas/IntermediateCanvas.js

@@ -119,7 +119,7 @@ IntermediateCanvasRenderer.prototype.forEachFeatureAtCoordinate = function(coord
 /**
  * @inheritDoc
  */
-IntermediateCanvasRenderer.prototype.forEachLayerAtCoordinate = function(coordinate, frameState, callback, thisArg) {
+IntermediateCanvasRenderer.prototype.forEachLayerAtCoordinate = function(coordinate, frameState, hitTolerance, callback, thisArg) {
   if (!this.getImage()) {
     return undefined;
   }
@@ -147,4 +147,5 @@ IntermediateCanvasRenderer.prototype.forEachLayerAtCoordinate = function(coordin
     }
   }
 };
+
 export default IntermediateCanvasRenderer;

src/ol/renderer/canvas/Layer.js

@@ -101,14 +101,15 @@ CanvasLayerRenderer.prototype.dispatchComposeEvent_ = function(type, context, fr
 /**
  * @param {module:ol/coordinate~Coordinate} coordinate Coordinate.
  * @param {module:ol/PluggableMap~FrameState} frameState FrameState.
+ * @param {number} hitTolerance Hit tolerance in pixels.
  * @param {function(this: S, module:ol/layer/Layer, (Uint8ClampedArray|Uint8Array)): T} callback Layer
  *     callback.
  * @param {S} thisArg Value to use as `this` when executing `callback`.
  * @return {T|undefined} Callback result.
  * @template S,T,U
  */
-CanvasLayerRenderer.prototype.forEachLayerAtCoordinate = function(coordinate, frameState, callback, thisArg) {
-  const hasFeature = this.forEachFeatureAtCoordinate(coordinate, frameState, 0, TRUE, this);
+CanvasLayerRenderer.prototype.forEachLayerAtCoordinate = function(coordinate, frameState, hitTolerance, callback, thisArg) {
+  const hasFeature = this.forEachFeatureAtCoordinate(coordinate, frameState, hitTolerance, TRUE, this);
 
   if (hasFeature) {
     return callback.call(thisArg, this.getLayer(), null);

src/ol/renderer/canvas/Map.js

@@ -182,7 +182,7 @@ CanvasMapRenderer.prototype.renderFrame = function(frameState) {
 /**
  * @inheritDoc
  */
-CanvasMapRenderer.prototype.forEachLayerAtPixel = function(pixel, frameState, callback, thisArg,
+CanvasMapRenderer.prototype.forEachLayerAtPixel = function(pixel, frameState, hitTolerance, callback, thisArg,
   layerFilter, thisArg2) {
   let result;
   const viewState = frameState.viewState;
@@ -201,7 +201,7 @@ CanvasMapRenderer.prototype.forEachLayerAtPixel = function(pixel, frameState, ca
     if (visibleAtResolution(layerState, viewResolution) && layerFilter.call(thisArg2, layer)) {
       const layerRenderer = /** @type {module:ol/renderer/canvas/Layer} */ (this.getLayerRenderer(layer));
       result = layerRenderer.forEachLayerAtCoordinate(
-        coordinate, frameState, callback, thisArg);
+        coordinate, frameState, hitTolerance, callback, thisArg);
       if (result) {
         return result;
       }

src/ol/renderer/webgl/Map.js

@@ -557,7 +557,7 @@ WebGLMapRenderer.prototype.hasFeatureAtCoordinate = function(coordinate, frameSt
 /**
  * @inheritDoc
  */
-WebGLMapRenderer.prototype.forEachLayerAtPixel = function(pixel, frameState, callback, thisArg,
+WebGLMapRenderer.prototype.forEachLayerAtPixel = function(pixel, frameState, hitTolerance, callback, thisArg,
   layerFilter, thisArg2) {
   if (this.getGL().isContextLost()) {
     return false;

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

@@ -163,6 +163,88 @@ describe('ol.renderer.canvas.Map', function() {
     });
   });
 
+  describe('#forEachLayerAtCoordinate', function() {
+
+    let layer, map, target;
+
+    beforeEach(function(done) {
+      target = document.createElement('div');
+      target.style.width = '100px';
+      target.style.height = '100px';
+      document.body.appendChild(target);
+      map = new Map({
+        pixelRatio: 1,
+        target: target,
+        view: new View({
+          center: [0, 0],
+          zoom: 0
+        })
+      });
+
+      // 1 x 1 pixel black icon
+      const img = document.createElement('img');
+      img.onload = function() {
+        done();
+      };
+      img.src = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAAAAAA6fptVAAAACklEQVR4nGNiAAAABgADNjd8qAAAAABJRU5ErkJggg==';
+
+      layer = new VectorLayer({
+        source: new VectorSource({
+          features: [
+            new Feature({
+              geometry: new Point([0, 0])
+            })
+          ]
+        }),
+        style: new Style({
+          image: new Icon({
+            img: img,
+            imgSize: [1, 1]
+          })
+        })
+      });
+    });
+
+    afterEach(function() {
+      map.setTarget(null);
+      document.body.removeChild(target);
+    });
+
+    it('calls callback for clicks inside of the hitTolerance', function() {
+      map.addLayer(layer);
+      map.renderSync();
+      const cb1 = sinon.spy();
+      const cb2 = sinon.spy();
+
+      const pixel = map.getPixelFromCoordinate([0, 0]);
+
+      const pixelsInside = [
+        [pixel[0] + 9, pixel[1]],
+        [pixel[0] - 9, pixel[1]],
+        [pixel[0], pixel[1] + 9],
+        [pixel[0], pixel[1] - 9]
+      ];
+
+      const pixelsOutside = [
+        [pixel[0] + 9, pixel[1] + 9],
+        [pixel[0] - 9, pixel[1] + 9],
+        [pixel[0] + 9, pixel[1] - 9],
+        [pixel[0] - 9, pixel[1] - 9]
+      ];
+
+      for (let i = 0; i < 4; i++) {
+        map.forEachLayerAtPixel(pixelsInside[i], cb1, {hitTolerance: 10});
+      }
+      expect(cb1.callCount).to.be(4);
+      expect(cb1.firstCall.args[0]).to.be(layer);
+
+      for (let j = 0; j < 4; j++) {
+        map.forEachLayerAtPixel(pixelsOutside[j], cb2, {hitTolerance: 10});
+      }
+      expect(cb2).not.to.be.called();
+    });
+  });
+
   describe('#renderFrame()', function() {
     let layer, map, renderer;