Recompute hover on click to increase click robustness

Author: rreusser

src/plots/cartesian/graph_interact.js

@@ -149,7 +149,7 @@ fx.init = function(gd) {
             };
 
             maindrag.onclick = function(evt) {
-                fx.click(gd, evt);
+                fx.click(gd, evt, subplot);
             };
 
             // corner draggers
@@ -300,8 +300,8 @@ fx.hover = function(gd, evt, subplot) {
 
 // The actual implementation is here:
 
-function hover(gd, evt, subplot) {
-    if(subplot === 'pie') {
+function hover(gd, evt, subplot, noHoverEvent) {
+    if(subplot === 'pie' && !noHoverEvent) {
         gd.emit('plotly_hover', {
             event: evt.originalEvent,
             points: [evt]
@@ -635,7 +635,7 @@ 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', {
@@ -1526,9 +1526,13 @@ function hoverChanged(gd, evt, oldhoverdata) {
 }
 
 // on click
-fx.click = function(gd, evt) {
+fx.click = function(gd, evt, subplot) {
     var annotationsDone = Registry.getComponentMethod('annotations', 'onClick')(gd, gd._hoverdata);
 
+    // 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.
+    fx.hover(gd, evt, subplot, true);
+
     function emitClick() { gd.emit('plotly_click', {points: gd._hoverdata, event: evt}); }
 
     if(gd._hoverdata && evt && evt.target) {

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

@@ -544,6 +544,23 @@ 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);