From 791f8b9917dbb744fb156da4cc8157fbb0f619f1 Mon Sep 17 00:00:00 2001
From: Kevin Schmidt <kschmidt@caci.com>
Date: Mon, 29 Jan 2018 15:02:54 -0700
Subject: [PATCH] Don't assume fill for canvas polygon hit detection.

This brings canvas polygon hit detection in parity with WebGL, where an
unfilled polygon will not be hit detected hovering inside the polygon.

Fixes #4846
---
 src/ol/render/canvas/PolygonReplay.js | 40 ++++++++++++++++-----------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/src/ol/render/canvas/PolygonReplay.js b/src/ol/render/canvas/PolygonReplay.js
index 879ebff636..6e1fa43ea5 100644
--- a/src/ol/render/canvas/PolygonReplay.js
+++ b/src/ol/render/canvas/PolygonReplay.js
@@ -61,9 +61,9 @@ CanvasPolygonReplay.prototype.drawFlatCoordinatess_ = function(flatCoordinates,
     }
     offset = end;
   }
-  this.hitDetectionInstructions.push(fillInstruction);
   if (fill) {
     this.instructions.push(fillInstruction);
+    this.hitDetectionInstructions.push(fillInstruction);
   }
   if (stroke) {
     this.instructions.push(strokeInstruction);
@@ -85,11 +85,12 @@ CanvasPolygonReplay.prototype.drawCircle = function(circleGeometry, feature) {
   }
   this.setFillStrokeStyles_(circleGeometry);
   this.beginGeometry(circleGeometry, feature);
-  // always fill the circle for hit detection
-  this.hitDetectionInstructions.push([
-    CanvasInstruction.SET_FILL_STYLE,
-    asString(defaultFillStyle)
-  ]);
+  if (state.fillStyle !== undefined) {
+    this.hitDetectionInstructions.push([
+      CanvasInstruction.SET_FILL_STYLE,
+      asString(defaultFillStyle)
+    ]);
+  }
   if (state.strokeStyle !== undefined) {
     this.hitDetectionInstructions.push([
       CanvasInstruction.SET_STROKE_STYLE,
@@ -122,13 +123,19 @@ CanvasPolygonReplay.prototype.drawCircle = function(circleGeometry, feature) {
  */
 CanvasPolygonReplay.prototype.drawPolygon = function(polygonGeometry, feature) {
   const state = this.state;
+  const fillStyle = state.fillStyle;
+  const strokeStyle = state.strokeStyle;
+  if (fillStyle === undefined && strokeStyle === undefined) {
+    return;
+  }
   this.setFillStrokeStyles_(polygonGeometry);
   this.beginGeometry(polygonGeometry, feature);
-  // always fill the polygon for hit detection
-  this.hitDetectionInstructions.push([
-    CanvasInstruction.SET_FILL_STYLE,
-    asString(defaultFillStyle)]
-  );
+  if (state.fillStyle !== undefined) {
+    this.hitDetectionInstructions.push([
+      CanvasInstruction.SET_FILL_STYLE,
+      asString(defaultFillStyle)
+    ]);
+  }
   if (state.strokeStyle !== undefined) {
     this.hitDetectionInstructions.push([
       CanvasInstruction.SET_STROKE_STYLE,
@@ -156,11 +163,12 @@ CanvasPolygonReplay.prototype.drawMultiPolygon = function(multiPolygonGeometry,
   }
   this.setFillStrokeStyles_(multiPolygonGeometry);
   this.beginGeometry(multiPolygonGeometry, feature);
-  // always fill the multi-polygon for hit detection
-  this.hitDetectionInstructions.push([
-    CanvasInstruction.SET_FILL_STYLE,
-    asString(defaultFillStyle)
-  ]);
+  if (state.fillStyle !== undefined) {
+    this.hitDetectionInstructions.push([
+      CanvasInstruction.SET_FILL_STYLE,
+      asString(defaultFillStyle)
+    ]);
+  }
   if (state.strokeStyle !== undefined) {
     this.hitDetectionInstructions.push([
       CanvasInstruction.SET_STROKE_STYLE,