bar: replace t.dbar with t.bargroupwidth

* Don't assume the position axis is `xa` in the calculation of
  `barDelta` in `bar/hover.js`.

* Updated `tests/bar_test.js` to account for the replacement of `t.bar`
  with `t.bargroupwidth`.

* Updated the group case in `tests/bar_test.js` to test the use of
  `layout.bargroupgap`.

Author: n-riesco

src/traces/bar/hover.js

@@ -21,7 +21,8 @@ module.exports = function hoverPoints(pointData, xval, yval, hovermode) {
         xa = pointData.xa,
         ya = pointData.ya,
         barDelta = (hovermode === 'closest') ?
-            t.barwidth / 2 : t.dbar * (1 - xa._gd._fullLayout.bargap) / 2,
+            t.barwidth / 2 :
+            t.bargroupwidth,
         barPos;
 
     if(hovermode !== 'closest') barPos = function(di) { return di.p; };

src/traces/bar/set_positions.js

@@ -105,26 +105,26 @@ function setOffsetAndWidth(gd, pa, pLetter, traces) {
     Axes.expand(pa, distinctPositions, {vpad: minDiff / 2});
 
     // computer bar widths and position offsets
-    var barWidth = minDiff * (1 - fullLayout.bargap);
-    if(overlap) barWidth /= traces.length;
-
-    var barWidthMinusGroupGap = barWidth * (1 - fullLayout.bargroupgap);
+    var barGroupWidth = minDiff * (1 - fullLayout.bargap),
+        barWidthPlusGap = (overlap) ?
+            barGroupWidth / traces.length :
+            barGroupWidth,
+        barWidth = barWidthPlusGap * (1 - fullLayout.bargroupgap);
 
     for(i = 0; i < traces.length; i++) {
         trace = traces[i];
 
         // computer bar group center and bar offset
-        var offsetFromCenter = (
-                (overlap ? (2 * i + 1 - traces.length) * barWidth : 0) -
-                barWidthMinusGroupGap
-            ) / 2,
-            barCenter = offsetFromCenter + barWidthMinusGroupGap / 2;
+        var offsetFromCenter = (overlap) ?
+                ((2 * i + 1 - traces.length) * barWidthPlusGap - barWidth) / 2 :
+                -barWidth / 2,
+            barCenter = offsetFromCenter + barWidth / 2;
 
         // store bar width and offset for this trace
         var t = trace[0].t;
-        t.barwidth = barWidthMinusGroupGap;
+        t.barwidth = barWidth;
         t.poffset = offsetFromCenter;
-        t.dbar = minDiff;
+        t.bargroupwidth = barGroupWidth;
 
         // store the bar center in each calcdata item
         for(j = 0; j < trace.length; j++) {

test/jasmine/tests/bar_test.js

@@ -142,7 +142,7 @@ describe('heatmap calc / setPositions', function() {
         assertPtField(out, 'p', [[0, 1, 2], [0, 1, 2], [0, 1, 2]]);
         assertTraceField(out, 't.barwidth', [0.8, 0.8, 0.8]);
         assertTraceField(out, 't.poffset', [-0.4, -0.4, -0.4]);
-        assertTraceField(out, 't.dbar', [1, 1, 1]);
+        assertTraceField(out, 't.bargroupwidth', [0.8, 0.8, 0.8]);
     });
 
     it('should fill in calc pt fields (overlay case)', function() {
@@ -161,7 +161,7 @@ describe('heatmap calc / setPositions', function() {
         assertPtField(out, 'p', [[0, 1, 2], [0, 1, 2]]);
         assertTraceField(out, 't.barwidth', [0.8, 0.8]);
         assertTraceField(out, 't.poffset', [-0.4, -0.4]);
-        assertTraceField(out, 't.dbar', [1, 1]);
+        assertTraceField(out, 't.bargroupwidth', [0.8, 0.8]);
     });
 
     it('should fill in calc pt fields (group case)', function() {
@@ -170,17 +170,19 @@ describe('heatmap calc / setPositions', function() {
         }, {
             y: [3, 1, 2]
         }], {
-            barmode: 'group'
+            barmode: 'group',
+            // asumming default bargap is 0.2
+            bargroupgap: 0.1
         });
 
         assertPtField(out, 'x', [[-0.2, 0.8, 1.8], [0.2, 1.2, 2.2]]);
         assertPtField(out, 'y', [[2, 1, 2], [3, 1, 2]]);
         assertPtField(out, 'b', [[0, 0, 0], [0, 0, 0]]);
         assertPtField(out, 's', [[2, 1, 2], [3, 1, 2]]);
         assertPtField(out, 'p', [[0, 1, 2], [0, 1, 2]]);
-        assertTraceField(out, 't.barwidth', [0.4, 0.4]);
-        assertTraceField(out, 't.poffset', [-0.4, 0]);
-        assertTraceField(out, 't.dbar', [1, 1]);
+        assertTraceField(out, 't.barwidth', [0.36, 0.36]);
+        assertTraceField(out, 't.poffset', [-0.38, 0.02]);
+        assertTraceField(out, 't.bargroupwidth', [0.8, 0.8]);
     });
 
     it('should fill in calc pt fields (relative case)', function() {
@@ -199,7 +201,7 @@ describe('heatmap calc / setPositions', function() {
         assertPtField(out, 'p', [[0, 1, 2], [0, 1, 2]]);
         assertTraceField(out, 't.barwidth', [0.8, 0.8]);
         assertTraceField(out, 't.poffset', [-0.4, -0.4]);
-        assertTraceField(out, 't.dbar', [1, 1]);
+        assertTraceField(out, 't.bargroupwidth', [0.8, 0.8]);
     });
 
     it('should fill in calc pt fields (relative / percent case)', function() {
@@ -221,6 +223,6 @@ describe('heatmap calc / setPositions', function() {
         assertPtField(out, 'p', [[0, 1, 2, 3], [0, 1, 2, 3]]);
         assertTraceField(out, 't.barwidth', [0.8, 0.8]);
         assertTraceField(out, 't.poffset', [-0.4, -0.4]);
-        assertTraceField(out, 't.dbar', [1, 1]);
+        assertTraceField(out, 't.bargroupwidth', [0.8, 0.8]);
     });
 });