Pick closest points to the winning point in compare mode and position unified hover box in front of winning point

src/components/fx/hover.js

@@ -39,6 +39,13 @@ var YSHIFTY = Math.sin(YA_RADIANS);
 var HOVERARROWSIZE = constants.HOVERARROWSIZE;
 var HOVERTEXTPAD = constants.HOVERTEXTPAD;
 
+var multipleHoverPoints = {
+    box: true,
+    ohlc: true,
+    violin: true,
+    candlestick: true
+};
+
 // fx.hover: highlight data on hover
 // evt can be a mousemove event, or an object with data about what points
 //   to hover on
@@ -651,39 +658,58 @@ function _hover(gd, evt, subplot, noHoverEvent) {
     };
     sortHoverData();
 
-    // If in compare mode, select every point at position
     if(
         helpers.isXYhover(_mode) &&
         hoverData[0].length !== 0 &&
         hoverData[0].trace.type !== 'splom' // TODO: add support for splom
     ) {
+        // pick winning point
         var winningPoint = hoverData[0];
+        // discard other points
+        if(multipleHoverPoints[winningPoint.trace.type]) {
+            hoverData = hoverData.filter(function(d) {
+                return d.trace.index === winningPoint.trace.index;
+            });
+        } else {
+            hoverData = [winningPoint];
+        }
+        var initLen = hoverData.length;
 
-        var customXVal = customVal('x', winningPoint, fullLayout);
-        var customYVal = customVal('y', winningPoint, fullLayout);
+        var winX = getCoord('x', winningPoint, fullLayout);
+        var winY = getCoord('y', winningPoint, fullLayout);
 
-        findHoverPoints(customXVal, customYVal);
+        // in compare mode, select every point at position
+        findHoverPoints(winX, winY);
 
         var finalPoints = [];
         var seen = {};
-        var insert = function(hd) {
-            var type = hd.trace.type;
-            var key = (
-                type === 'box' ||
-                type === 'violin' ||
-                type === 'ohlc' ||
-                type === 'candlestick'
-            ) ? hoverDataKey(hd) : hd.trace.index;
+        var id = 0;
+        var insert = function(newHd) {
+            var key = multipleHoverPoints[newHd.trace.type] ? hoverDataKey(newHd) : newHd.trace.index;
             if(!seen[key]) {
-                seen[key] = true;
-                finalPoints.push(hd);
+                id++;
+                seen[key] = id;
+                finalPoints.push(newHd);
+            } else {
+                var oldId = seen[key] - 1;
+                var oldHd = finalPoints[oldId];
+                if(oldId > 0 &&
+                    Math.abs(newHd.distance) <
+                    Math.abs(oldHd.distance)
+                ) {
+                    // replace with closest
+                    finalPoints[oldId] = newHd;
+                }
             }
         };
 
-        // insert the winnig point first
-        insert(winningPoint);
+        var k;
+        // insert the winnig point(s) first
+        for(k = 0; k < initLen; k++) {
+            insert(hoverData[k]);
+        }
         // override from the end
-        for(var k = hoverData.length - 1; k > 0; k--) {
+        for(k = hoverData.length - 1; k > initLen - 1; k--) {
             insert(hoverData[k]);
         }
         hoverData = finalPoints;
@@ -1045,8 +1071,9 @@ function createHoverText(hoverData, opts, gd) {
         legendDraw(gd, mockLegend);
 
         // Position the hover
-        var ly = Lib.mean(hoverData.map(function(c) {return (c.y0 + c.y1) / 2;}));
-        var lx = Lib.mean(hoverData.map(function(c) {return (c.x0 + c.x1) / 2;}));
+        var winningPoint = hoverData[0];
+        var ly = (winningPoint.y0 + winningPoint.y1) / 2;
+        var lx = (winningPoint.x0 + winningPoint.x1) / 2;
         var legendContainer = container.select('g.legend');
         var tbb = legendContainer.node().getBoundingClientRect();
         lx += xa._offset;
@@ -1892,7 +1919,7 @@ function orderRangePoints(hoverData, hovermode) {
     return first.concat(second).concat(last);
 }
 
-function customVal(axLetter, winningPoint, fullLayout) {
+function getCoord(axLetter, winningPoint, fullLayout) {
     var ax = winningPoint[axLetter + 'a'];
     var val = winningPoint[axLetter + 'Val'];
 

src/traces/bar/hover.js

@@ -35,14 +35,35 @@ function hoverOnBars(pointData, xval, yval, hovermode, opts) {
 
     var posVal, sizeVal, posLetter, sizeLetter, dx, dy, pRangeCalc;
 
+    if(trace.orientation === 'h') {
+        posVal = yval;
+        sizeVal = xval;
+        posLetter = 'y';
+        sizeLetter = 'x';
+        dx = sizeFn;
+        dy = positionFn;
+    } else {
+        posVal = xval;
+        sizeVal = yval;
+        posLetter = 'x';
+        sizeLetter = 'y';
+        dy = sizeFn;
+        dx = positionFn;
+    }
+
+    var period = trace[posLetter + 'period'];
+
     function thisBarMinPos(di) { return thisBarExtPos(di, -1); }
     function thisBarMaxPos(di) { return thisBarExtPos(di, 1); }
 
     function thisBarExtPos(di, sgn) {
-        return di[posLetter] + 0.5 * sgn * di.w;
+        if(period) {
+            return di.p + sgn * Math.abs(di.p - di.orig_p);
+        }
+        return di[posLetter] + sgn * di.w / 2;
     }
 
-    var minPos = isClosest ?
+    var minPos = isClosest || period ?
         thisBarMinPos :
         function(di) {
             /*
@@ -60,7 +81,7 @@ function hoverOnBars(pointData, xval, yval, hovermode, opts) {
             return Math.min(thisBarMinPos(di), di.p - t.bardelta / 2);
         };
 
-    var maxPos = isClosest ?
+    var maxPos = isClosest || period ?
         thisBarMaxPos :
         function(di) {
             return Math.max(thisBarMaxPos(di), di.p + t.bardelta / 2);
@@ -118,22 +139,6 @@ function hoverOnBars(pointData, xval, yval, hovermode, opts) {
         return Fx.inbox(b - v, s - v, maxSpikeDistance + (s - v) / (s - b) - 1);
     }
 
-    if(trace.orientation === 'h') {
-        posVal = yval;
-        sizeVal = xval;
-        posLetter = 'y';
-        sizeLetter = 'x';
-        dx = sizeFn;
-        dy = positionFn;
-    } else {
-        posVal = xval;
-        sizeVal = yval;
-        posLetter = 'x';
-        sizeLetter = 'y';
-        dy = sizeFn;
-        dx = positionFn;
-    }
-
     var pa = pointData[posLetter + 'a'];
     var sa = pointData[sizeLetter + 'a'];
 

src/traces/scatter/hover.js

@@ -28,13 +28,14 @@ module.exports = function hoverPoints(pointData, xval, yval, hovermode) {
             var rad = Math.max(3, di.mrc || 0);
             var kink = 1 - 1 / rad;
             var dxRaw = Math.abs(xa.c2p(di.x) - xpx);
-            var d = (dxRaw < rad) ? (kink * dxRaw / rad) : (dxRaw - rad + kink);
-            return d;
+            if(di.orig_x !== undefined) dxRaw += xa.c2p(di.orig_x) - xa.c2p(di.x);
+            return (dxRaw < rad) ? (kink * dxRaw / rad) : (dxRaw - rad + kink);
         };
         var dy = function(di) {
             var rad = Math.max(3, di.mrc || 0);
             var kink = 1 - 1 / rad;
             var dyRaw = Math.abs(ya.c2p(di.y) - ypx);
+            if(di.orig_y !== undefined) dyRaw += ya.c2p(di.orig_y) - ya.c2p(di.y);
             return (dyRaw < rad) ? (kink * dyRaw / rad) : (dyRaw - rad + kink);
         };
         var dxy = function(di) {

src/traces/scattergl/hover.js

@@ -48,9 +48,11 @@ function hoverPoints(pointData, xval, yval, hovermode) {
         for(i = 0; i < ids.length; i++) {
             ptx = x[ids[i]];
             dx = Math.abs(xa.c2p(ptx) - xpx);
+            if(trace._origX && trace._origX[i] !== undefined) dx += xa.c2p(trace._origX[i]) - xa.c2p(ptx);
             if(dx < minDist) {
                 minDist = dx;
                 dy = ya.c2p(y[ids[i]]) - ypx;
+                if(trace._origY && trace._origY[i] !== undefined) dy += ya.c2p(trace._origY[i]) - ya.c2p(pty);
                 dxy = Math.sqrt(dx * dx + dy * dy);
                 id = ids[i];
             }