Recompute hover on click to increase click robustness

src/components/fx/click.js

@@ -9,10 +9,19 @@
 'use strict';
 
 var Registry = require('../../registry');
+var hover = require('./hover').hover;
 
-module.exports = function click(gd, evt) {
+module.exports = function click(gd, evt, subplot) {
     var annotationsDone = Registry.getComponentMethod('annotations', 'onClick')(gd, gd._hoverdata);
 
+    // fallback to fail-safe in case the plot type's hover method doesn't pass the subplot.
+    // Ternary, for example, didn't, but it was caught because tested.
+    if(subplot !== undefined) {
+        // The true flag at the end causes it to re-run the hover computation to figure out *which*
+        // point is being clicked. Without this, clicking is somewhat unreliable.
+        hover(gd, evt, subplot, true);
+    }
+
     function emitClick() { gd.emit('plotly_click', {points: gd._hoverdata, event: evt}); }
 
     if(gd._hoverdata && evt && evt.target) {

src/components/fx/hover.js

@@ -66,7 +66,7 @@ var HOVERTEXTPAD = constants.HOVERTEXTPAD;
 //
 // We wrap the hovers in a timer, to limit their frequency.
 // The actual rendering is done by private function _hover.
-exports.hover = function hover(gd, evt, subplot) {
+exports.hover = function hover(gd, evt, subplot, noHoverEvent) {
     if(typeof gd === 'string') gd = document.getElementById(gd);
     if(gd._lastHoverTime === undefined) gd._lastHoverTime = 0;
 
@@ -78,13 +78,13 @@ exports.hover = function hover(gd, evt, subplot) {
     // Is it more than 100ms since the last update?  If so, force
     // an update now (synchronously) and exit
     if(Date.now() > gd._lastHoverTime + constants.HOVERMINTIME) {
-        _hover(gd, evt, subplot);
+        _hover(gd, evt, subplot, noHoverEvent);
         gd._lastHoverTime = Date.now();
         return;
     }
     // Queue up the next hover for 100ms from now (if no further events)
     gd._hoverTimer = setTimeout(function() {
-        _hover(gd, evt, subplot);
+        _hover(gd, evt, subplot, noHoverEvent);
         gd._lastHoverTime = Date.now();
         gd._hoverTimer = undefined;
     }, constants.HOVERMINTIME);
@@ -168,8 +168,8 @@ exports.loneHover = function loneHover(hoverItem, opts) {
 };
 
 // The actual implementation is here:
-function _hover(gd, evt, subplot) {
-    if(subplot === 'pie' || subplot === 'sankey') {
+function _hover(gd, evt, subplot, noHoverEvent) {
+    if((subplot === 'pie' || subplot === 'sankey') && !noHoverEvent) {
         gd.emit('plotly_hover', {
             event: evt.originalEvent,
             points: [evt]
@@ -504,7 +504,7 @@ function _hover(gd, evt, subplot) {
     }
 
     // don't emit events if called manually
-    if(!evt.target || !hoverChanged(gd, evt, oldhoverdata)) return;
+    if(!evt.target || noHoverEvent || !hoverChanged(gd, evt, oldhoverdata)) return;
 
     if(oldhoverdata) {
         gd.emit('plotly_unhover', {

src/plots/cartesian/graph_interact.js

@@ -97,7 +97,7 @@ module.exports = function initInteractions(gd) {
             };
 
             maindrag.onclick = function(evt) {
-                Fx.click(gd, evt);
+                Fx.click(gd, evt, subplot);
             };
 
             // corner draggers

src/plots/ternary/ternary.js

@@ -631,7 +631,7 @@ proto.initInteractions = function() {
     };
 
     dragger.onclick = function(evt) {
-        Fx.click(gd, evt);
+        Fx.click(gd, evt, _this.id);
     };
 
     dragElement.init(dragOptions);

test/jasmine/tests/hover_label_test.js

@@ -587,6 +587,23 @@ describe('hover info', function() {
             Plotly.plot(gd, data, layout).then(done);
         });
 
+        it('should skip the hover event if explicitly instructed', function(done) {
+            var hoverHandler = jasmine.createSpy();
+            gd.on('plotly_hover', hoverHandler);
+
+            var gdBB = gd.getBoundingClientRect();
+            var event = {clientX: gdBB.left + 300, clientY: gdBB.top + 200};
+
+            Promise.resolve().then(function() {
+                Fx.hover(gd, event, 'xy', true);
+            })
+            .then(function() {
+                expect(hoverHandler).not.toHaveBeenCalled();
+            })
+            .catch(fail)
+            .then(done);
+        });
+
         it('should emit events only if the event looks user-driven', function(done) {
             var hoverHandler = jasmine.createSpy();
             gd.on('plotly_hover', hoverHandler);