position hover label above circular links

Author: antoinerg

src/traces/sankey/plot.js

@@ -151,16 +151,23 @@ module.exports = function plot(gd, calcData) {
         var obj = d.link.trace.link;
         if(obj.hoverinfo === 'none' || obj.hoverinfo === 'skip') return;
         var rootBBox = gd._fullLayout._paperdiv.node().getBoundingClientRect();
-        var boundingBox = element.getBoundingClientRect();
-        var hoverCenterX = boundingBox.left + boundingBox.width / 2;
-        var hoverCenterY = boundingBox.top + boundingBox.height / 2;
+        var hoverCenterX;
+        var hoverCenterY;
+        if(d.link.circular) {
+            hoverCenterX = (d.link.circularPathData.leftInnerExtent + d.link.circularPathData.rightInnerExtent) / 2 + d.parent.translateX;
+            hoverCenterY = d.link.circularPathData.verticalFullExtent + d.parent.translateY;
+        } else {
+            var boundingBox = element.getBoundingClientRect();
+            hoverCenterX = boundingBox.left + boundingBox.width / 2 - rootBBox.left;
+            hoverCenterY = boundingBox.top + boundingBox.height / 2 - rootBBox.top;
+        }
 
         var hovertemplateLabels = {valueLabel: d3.format(d.valueFormat)(d.link.value) + d.valueSuffix};
         d.link.fullData = d.link.trace;
 
         var tooltip = Fx.loneHover({
-            x: hoverCenterX - rootBBox.left,
-            y: hoverCenterY - rootBBox.top,
+            x: hoverCenterX,
+            y: hoverCenterY,
             name: hovertemplateLabels.valueLabel,
             text: [
                 d.link.label || '',

src/traces/sankey/render.js

@@ -120,6 +120,7 @@ function linkModel(d, l, i) {
         valueFormat: d.valueFormat,
         valueSuffix: d.valueSuffix,
         sankey: d.sankey,
+        parent: d,
         interactionState: d.interactionState
     };
 }