Expose legendText as a method of ChartInternal

src/legend.js

@@ -123,6 +123,14 @@ var legendItemTextBox = {};
 c3_chart_internal_fn.clearLegendItemTextBoxCache = function () {
     legendItemTextBox = {};
 };
+
+c3_chart_internal_fn.legendText = function (id){
+    var $$ = this;
+    return isDefined($$.config.data_names[id]) ?
+           $$.config.data_names[id] :
+           isDefined($$.config.data_names.id) ? $$.config.data_names.id : id; 
+};
+
 c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
     var $$ = this, config = $$.config;
     var xForLegend, xForLegendText, xForLegendRect, yForLegend, yForLegendText, yForLegendRect;
@@ -140,10 +148,6 @@ c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
     
     $$.clearLegendItemTextBoxCache();
 
-    function legendText(id){
-        return isDefined(config.data_names[id]) ? config.data_names[id] : isDefined(config.data_names.id) ? config.data_names.id : id; 
-    }
-
     function getTextBox(textElement, id) {
         if (!legendItemTextBox[id]) {
             legendItemTextBox[id] = $$.getTextRect(textElement.textContent, '.c3-legend-item');
@@ -280,7 +284,7 @@ c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
             }
         });
     l.append('text')
-        .text(legendText)
+        .text($$.legendText.bind($$))
         .each(function (id, i) { updatePositions(this, id, i); })
         .style("pointer-events", "none")
         .attr('x', $$.isLegendRight || $$.isLegendInset ? xForLegendText : -200)
@@ -309,7 +313,7 @@ c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
 
     texts = $$.legend.selectAll('text')
         .data(targetIds)
-        .text(legendText) // MEMO: needed for update
+        .text($$.legendText.bind($$)) // MEMO: needed for update
         .each(function (id, i) { updatePositions(this, id, i); });
     (withTransition ? texts.transition() : texts)
         .attr('x', xForLegendText)