Expose pixel coordinates of hover event data and fire hover events even if near trace

Author: alexshoe

src/components/fx/hover.js

@@ -167,6 +167,9 @@ exports.loneHover = function loneHover(hoverItems, opts) {
                 y1: y1 + gTop
             };
 
+            eventData.xPixel = (_x0 + _x1) / 2;
+            eventData.yPixel = (_y0 + _y1) / 2;
+
             if (opts.inOut_bbox) {
                 opts.inOut_bbox.push(eventData.bbox);
             }
@@ -894,6 +897,9 @@ function _hover(gd, evt, subplot, noHoverEvent, eventTarget) {
                 y0: y0 + gTop,
                 y1: y1 + gTop
             };
+
+            eventData.xPixel = (_x0 + _x1) / 2;
+            eventData.yPixel = (_y0 + _y1) / 2;
         }
 
         pt.eventData = [eventData];
@@ -931,9 +937,10 @@ function _hover(gd, evt, subplot, noHoverEvent, eventTarget) {
     }
 
     // don't emit events if called manually
-    if (!eventTarget || noHoverEvent || !hoverChanged(gd, evt, oldhoverdata)) return;
+    var _hoverChanged = hoverChanged(gd, evt, oldhoverdata);
+    if (!eventTarget || noHoverEvent || (!_hoverChanged && !fullLayout.hoveranywhere)) return;
 
-    if (oldhoverdata) {
+    if (oldhoverdata && _hoverChanged) {
         gd.emit('plotly_unhover', {
             event: evt,
             points: oldhoverdata