Account for icon offsets when doing feature hit detection

src/ol/renderer/canvas/canvasvectorlayerrenderer.js

@@ -249,6 +249,7 @@ ol.renderer.canvas.VectorLayer.prototype.getFeaturesForPixel =
     var cachedTile = this.tileCache_.get(key);
     var symbolSizes = cachedTile[1];
     var maxSymbolSize = cachedTile[2];
+    var symbolOffsets = cachedTile[3];
     var halfMaxWidth = maxSymbolSize[0] / 2;
     var halfMaxHeight = maxSymbolSize[1] / 2;
     var locationMin = [location[0] - halfMaxWidth, location[1] - halfMaxHeight];
@@ -264,8 +265,8 @@ ol.renderer.canvas.VectorLayer.prototype.getFeaturesForPixel =
       return;
     }
 
-    var candidate, geom, type, symbolBounds, symbolSize, halfWidth, halfHeight,
-        coordinates, j;
+    var candidate, geom, type, symbolBounds, symbolSize, symbolOffset,
+        halfWidth, halfHeight, coordinates, j;
     for (var id in candidates) {
       candidate = candidates[id];
       geom = candidate.getGeometry();
@@ -275,11 +276,15 @@ ol.renderer.canvas.VectorLayer.prototype.getFeaturesForPixel =
         // For points, check if the pixel coordinate is inside the candidate's
         // symbol
         symbolSize = symbolSizes[goog.getUid(candidate)];
+        symbolOffset = symbolOffsets[goog.getUid(candidate)];
         halfWidth = symbolSize[0] / 2;
         halfHeight = symbolSize[1] / 2;
-        symbolBounds = ol.extent.boundingExtent(
-            [[location[0] - halfWidth, location[1] - halfHeight],
-              [location[0] + halfWidth, location[1] + halfHeight]]);
+        symbolBounds = ol.extent.boundingExtent([
+          [location[0] - halfWidth - symbolOffset[0],
+            location[1] - halfHeight + symbolOffset[1]],
+          [location[0] + halfWidth - symbolOffset[0],
+            location[1] + halfHeight + symbolOffset[1]]
+        ]);
         coordinates = geom.getCoordinates();
         if (!goog.isArray(coordinates[0])) {
           coordinates = [coordinates];
@@ -519,7 +524,8 @@ ol.renderer.canvas.VectorLayer.prototype.renderFrame =
   }
 
   var symbolSizes = sketchCanvasRenderer.getSymbolSizes(),
-      maxSymbolSize = sketchCanvasRenderer.getMaxSymbolSize();
+      maxSymbolSize = sketchCanvasRenderer.getMaxSymbolSize(),
+      symbolOffsets = sketchCanvasRenderer.getSymbolOffsets();
   for (key in tilesToRender) {
     tileCoord = tilesToRender[key];
     if (this.tileCache_.containsKey(key)) {
@@ -531,7 +537,8 @@ ol.renderer.canvas.VectorLayer.prototype.renderFrame =
           (tileRange.minX - tileCoord.x) * tileSize[0],
           (tileCoord.y - tileRange.maxY) * tileSize[1]);
       // TODO: Create an ol.VectorTile subclass of ol.Tile
-      this.tileCache_.set(key, [tile, symbolSizes, maxSymbolSize]);
+      this.tileCache_.set(key,
+          [tile, symbolSizes, maxSymbolSize, symbolOffsets]);
     }
     finalContext.drawImage(tile,
         tileSize[0] * (tileCoord.x - tileRange.minX),

src/ol/renderer/canvas/canvasvectorrenderer.js

@@ -73,6 +73,12 @@ ol.renderer.canvas.VectorRenderer =
    */
   this.symbolSizes_ = {};
 
+  /**
+   * @type {Object.<number, Array.<number>>}
+   * @private
+   */
+  this.symbolOffsets_ = {};
+
   /**
    * @type {Array.<number>}
    * @private
@@ -90,6 +96,14 @@ ol.renderer.canvas.VectorRenderer.prototype.getSymbolSizes = function() {
 };
 
 
+/**
+ * @return {Object.<number, Array.<number>>} Symbolizer offsets.
+ */
+ol.renderer.canvas.VectorRenderer.prototype.getSymbolOffsets = function() {
+  return this.symbolOffsets_;
+};
+
+
 /**
  * @return {Array.<number>} Maximum symbolizer size.
  */
@@ -232,6 +246,8 @@ ol.renderer.canvas.VectorRenderer.prototype.renderPointFeatures_ =
   var midHeight = content.height / 2;
   var contentWidth = content.width * this.inverseScale_;
   var contentHeight = content.height * this.inverseScale_;
+  var contentXOffset = xOffset * this.inverseScale_;
+  var contentYOffset = yOffset * this.inverseScale_;
   context.save();
   context.setTransform(1, 0, 0, 1, -midWidth, -midHeight);
   context.globalAlpha = alpha;
@@ -242,9 +258,13 @@ ol.renderer.canvas.VectorRenderer.prototype.renderPointFeatures_ =
     this.symbolSizes_[id] = goog.isDef(size) ?
         [Math.max(size[0], contentWidth), Math.max(size[1], contentHeight)] :
         [contentWidth, contentHeight];
+    this.symbolOffsets_[id] =
+        [xOffset * this.inverseScale_, yOffset * this.inverseScale_];
     this.maxSymbolSize_ =
-        [Math.max(this.maxSymbolSize_[0], this.symbolSizes_[id][0]),
-          Math.max(this.maxSymbolSize_[1], this.symbolSizes_[id][1])];
+        [Math.max(this.maxSymbolSize_[0],
+            this.symbolSizes_[id][0] + 2 * Math.abs(contentXOffset)),
+          Math.max(this.maxSymbolSize_[1],
+              this.symbolSizes_[id][1] + 2 * Math.abs(contentYOffset))];
     geometry = feature.getGeometry();
     if (geometry instanceof ol.geom.Point) {
       components = [geometry];