Implement forEachLayerAtPixel for canvas

src/ol/renderer/canvas/canvaslayerrenderer.js

@@ -216,6 +216,22 @@ ol.renderer.canvas.Layer.prototype.getTransform = function(frameState) {
 ol.renderer.canvas.Layer.prototype.prepareFrame = goog.abstractMethod;
 
 
+/**
+ * @param {ol.Coordinate} coordinate Coordinate.
+ * @param {goog.vec.Mat4.Number} imageTransformInv The transformation matrix
+ *        to convert from a map pixel to a canvas pixel.
+ * @return {ol.Pixel}
+ * @protected
+ */
+ol.renderer.canvas.Layer.prototype.getPixelFromCoordinates =
+    function(coordinate, imageTransformInv) {
+  var pixelOnMap = this.getMap().getPixelFromCoordinate(coordinate);
+  var pixelOnCanvas = [0, 0];
+  ol.vec.Mat4.multVec2(imageTransformInv, pixelOnMap, pixelOnCanvas);
+  return pixelOnCanvas;
+};
+
+
 /**
  * @param {ol.Size} size Size.
  * @return {boolean} True when the canvas with the current size does not exceed