rotate hover labels under a few more circumstances

- when hovermode:'y' and one trace with multiple hover labels
- when hovermode:'closest' and at leat one trace is 'horizontal'
  on the subplot.

- lock behavior in violin suite.

Author: etpinard

src/components/fx/hover.js

@@ -237,6 +237,10 @@ function _hover(gd, evt, subplot, noHoverEvent) {
         vLinePoint: null
     };
 
+    // does subplot have one (or more) horizontal traces,
+    // (to determine whether we rotate the labels or not)
+    var hasOneHorizontalTrace = false;
+
     // Figure out what we're hovering on:
     // mouse location or user-supplied data
 
@@ -256,6 +260,9 @@ function _hover(gd, evt, subplot, noHoverEvent) {
             trace = cd[0].trace;
             if(trace.hoverinfo !== 'skip' && helpers.isTraceInSubplots(trace, subplots)) {
                 searchData.push(cd);
+                if(trace.orientation === 'h') {
+                    hasOneHorizontalTrace = true;
+                }
             }
         }
 
@@ -577,9 +584,10 @@ function _hover(gd, evt, subplot, noHoverEvent) {
 
     gd._hoverdata = newhoverdata;
 
-    // if there's more than one horz bar trace,
-    // rotate the labels so they don't overlap
-    var rotateLabels = hovermode === 'y' && searchData.length > 1;
+    var rotateLabels = (
+        (hovermode === 'y' && (searchData.length > 1 || hoverData.length > 1)) ||
+        (hovermode === 'closest' && hasOneHorizontalTrace)
+    );
 
     var bgColor = Color.combine(
         fullLayout.plot_bgcolor || Color.background,

test/jasmine/assets/custom_assertions.js

@@ -90,6 +90,8 @@ function count(selector) {
  *  - nums {string || array of strings}
  *  - name {string || array of strings}
  *  - axis {string}
+ *  - vOrder {array of number}
+ *  - hOrder {array of number}
  * @param {string} msg
  */
 exports.assertHoverLabelContent = function(expectation, msg) {

test/jasmine/tests/violin_test.js

@@ -431,6 +431,48 @@ describe('Test violin hover:', function() {
         nums: 'x: 42.43046, kde: 0.083',
         name: '',
         axis: 'Saturday'
+    }, {
+        desc: 'single horizontal violin',
+        mock: require('@mocks/violin_non-linear.json'),
+        pos: [310, 160],
+        nums: ['median: C', 'min: A', 'q1: B', 'q3: D', 'max: G', 'upper fence: D', 'x: C, kde: 1.005'],
+        name: ['categories', '', '', '', '', '', ''],
+        axis: 'categories',
+        hOrder: [4, 5, 3, 6, 0, 2, 1],
+    }, {
+        desc: 'multiple horizontal violins',
+        mock: require('@mocks/box_grouped_horz.json'),
+        patch: function(fig) {
+            fig.data.forEach(function(t) {
+                t.type = 'violin';
+                t.hoveron = 'violins';
+            });
+            fig.layout.violinmode = 'group';
+            return fig;
+        },
+        nums: ['median: 0.4', 'min: 0.1', 'q1: 0.2', 'q3: 0.7', 'max: 0.9'],
+        name: ['kale', '', '', '', ''],
+        axis: 'day 2',
+        hOrder: [4, 3, 0, 2, 1],
+    }, {
+        desc: 'multiple horizontal violins (under hovermode:closest)',
+        mock: require('@mocks/box_grouped_horz.json'),
+        patch: function(fig) {
+            fig.data.forEach(function(t) {
+                t.type = 'violin';
+                t.hoveron = 'violins';
+            });
+            fig.layout.violinmode = 'group';
+            fig.layout.hovermode = 'closest';
+            return fig;
+        },
+        pos: [200, 175],
+        nums: [
+            '(median: 0.7, day 2)', '(min: 0.2, day 2)', '(q1: 0.5, day 2)',
+            '(q3: 0.8, day 2)', '(max: 0.9, day 2)'
+        ],
+        name: ['radishes', '', '', '', ''],
+        hOrder: [4, 3, 0, 2, 1],
     }]
     .forEach(function(specs) {
         it('should generate correct hover labels ' + specs.desc, function(done) {