clear ternary axis titles when ternary subplots are removed

- to do so more easily, make Titles.draw return the title
  group element.

Author: etpinard

src/components/titles/index.js

@@ -51,6 +51,8 @@ var numStripRE = / [XY][0-9]* /;
  *          offset - shift up/down in the rotated frame (unused?)
  *      containerGroup - if an svg <g> element already exists to hold this
  *          title, include here. Otherwise it will go in fullLayout._infolayer
+ *
+ *  @return {selection} d3 selection of title container group
  */
 Titles.draw = function(gd, titleClass, options) {
     var cont = options.propContainer;
@@ -111,7 +113,7 @@ Titles.draw = function(gd, titleClass, options) {
         .attr('class', titleClass);
     el.exit().remove();
 
-    if(!elShouldExist) return;
+    if(!elShouldExist) return group;
 
     function titleLayout(titleEl) {
         Lib.syncOrAsync([drawTitle, scootTitle], titleEl);
@@ -236,4 +238,6 @@ Titles.draw = function(gd, titleClass, options) {
             });
     }
     el.classed('js-placeholder', isplaceholder);
+
+    return group;
 };

src/plots/ternary/index.js

@@ -67,6 +67,9 @@ exports.clean = function(newFullData, newFullLayout, oldFullData, oldFullLayout)
             oldTernary.plotContainer.remove();
             oldTernary.clipDef.remove();
             oldTernary.clipDefRelative.remove();
+            oldTernary.layers['a-title'].remove();
+            oldTernary.layers['b-title'].remove();
+            oldTernary.layers['c-title'].remove();
         }
     }
 };

src/plots/ternary/ternary.js

@@ -380,7 +380,7 @@ proto.drawAxes = function(doTitles) {
         var apad = Math.max(aaxis.showticklabels ? aaxis.tickfont.size / 2 : 0,
             (caxis.showticklabels ? caxis.tickfont.size * 0.75 : 0) +
             (caxis.ticks === 'outside' ? caxis.ticklen * 0.87 : 0));
-        Titles.draw(gd, 'a' + titlesuffix, {
+        _this.layers['a-title'] = Titles.draw(gd, 'a' + titlesuffix, {
             propContainer: aaxis,
             propName: _this.id + '.aaxis.title',
             placeholder: _(gd, 'Click to enter Component A title'),
@@ -391,10 +391,11 @@ proto.drawAxes = function(doTitles) {
             }
         });
 
+
         var bpad = (baxis.showticklabels ? baxis.tickfont.size : 0) +
             (baxis.ticks === 'outside' ? baxis.ticklen : 0) + 3;
 
-        Titles.draw(gd, 'b' + titlesuffix, {
+        _this.layers['b-title'] = Titles.draw(gd, 'b' + titlesuffix, {
             propContainer: baxis,
             propName: _this.id + '.baxis.title',
             placeholder: _(gd, 'Click to enter Component B title'),
@@ -405,7 +406,7 @@ proto.drawAxes = function(doTitles) {
             }
         });
 
-        Titles.draw(gd, 'c' + titlesuffix, {
+        _this.layers['c-title'] = Titles.draw(gd, 'c' + titlesuffix, {
             propContainer: caxis,
             propName: _this.id + '.caxis.title',
             placeholder: _(gd, 'Click to enter Component C title'),

test/jasmine/tests/ternary_test.js

@@ -59,31 +59,42 @@ describe('ternary plots', function() {
         });
 
         it('should be able to delete and add traces', function(done) {
+            function checkTitles(cnt) {
+                expect(d3.selectAll('.g-atitle').size()).toBe(cnt, 'aaxis title');
+                expect(d3.selectAll('.g-btitle').size()).toBe(cnt, 'baxis title');
+                expect(d3.selectAll('.g-ctitle').size()).toBe(cnt, 'caxis title');
+            }
+
             expect(countTernarySubplot()).toEqual(1);
             expect(countTraces('scatter')).toEqual(1);
+            checkTitles(1);
 
             Plotly.deleteTraces(gd, [0]).then(function() {
                 expect(countTernarySubplot()).toEqual(0);
                 expect(countTraces('scatter')).toEqual(0);
+                checkTitles(0);
 
                 var trace = Lib.extendDeep({}, mock.data[0]);
 
                 return Plotly.addTraces(gd, [trace]);
             }).then(function() {
                 expect(countTernarySubplot()).toEqual(1);
                 expect(countTraces('scatter')).toEqual(1);
+                checkTitles(1);
 
                 var trace = Lib.extendDeep({}, mock.data[0]);
 
                 return Plotly.addTraces(gd, [trace]);
             }).then(function() {
                 expect(countTernarySubplot()).toEqual(1);
                 expect(countTraces('scatter')).toEqual(2);
+                checkTitles(1);
 
                 return Plotly.deleteTraces(gd, [0]);
             }).then(function() {
                 expect(countTernarySubplot()).toEqual(1);
                 expect(countTraces('scatter')).toEqual(1);
+                checkTitles(1);
 
                 done();
             });