Created updateCulling function in Axis

Fixes #1430

src/axis.js

@@ -320,6 +320,26 @@ Axis.prototype.updateLabels = function updateLabels(withTransition) {
         .attr("dy", this.dyForY2AxisLabel.bind(this))
         .text(this.textForY2AxisLabel.bind(this));
 };
+Axis.prototype.updateCulling = function updateCulling(tickValues) {
+    var $$ = this.owner, config = $$.config;
+    if (config.axis_x_tick_culling && tickValues) {
+        var intervalForCulling, i;
+        for (i = 1; i < tickValues.length; i++) {
+            if (tickValues.length / i < config.axis_x_tick_culling_max) {
+                intervalForCulling = i;
+                break;
+            }
+        }
+        $$.svg.selectAll('.' + CLASS.axisX + ' .tick text').each(function (e) {
+            var index = tickValues.indexOf(e);
+            if (index >= 0) {
+                d3.select(this).style('display', index % intervalForCulling ? 'none' : 'block');
+            }
+        });
+    } else {
+        $$.svg.selectAll('.' + CLASS.axisX + ' .tick text').style('display', 'block');
+    }
+};
 Axis.prototype.getPadding = function getPadding(padding, key, defaultValue, domainLength) {
     var p = typeof padding === 'number' ? padding : padding[key];
     if (!isValue(p)) {

src/core.js

@@ -466,7 +466,7 @@ c3_chart_internal_fn.redraw = function (options, transitions) {
     var drawArea, drawBar, drawLine, xForText, yForText;
     var duration, durationForExit, durationForAxis;
     var waitForDraw, flow;
-    var targetsToShow = $$.filterTargetsToShow($$.data.targets), tickValues, i, intervalForCulling, xDomainForZoom;
+    var targetsToShow = $$.filterTargetsToShow($$.data.targets), tickValues, xDomainForZoom;
     var xv = $$.xv.bind($$), cx, cy;
 
     options = options || {};
@@ -534,24 +534,8 @@ c3_chart_internal_fn.redraw = function (options, transitions) {
     // Update axis label
     $$.axis.updateLabels(withTransition);
 
-    // show/hide if manual culling needed
     if ((withUpdateXDomain || withUpdateXAxis) && targetsToShow.length) {
-        if (config.axis_x_tick_culling && tickValues) {
-            for (i = 1; i < tickValues.length; i++) {
-                if (tickValues.length / i < config.axis_x_tick_culling_max) {
-                    intervalForCulling = i;
-                    break;
-                }
-            }
-            $$.svg.selectAll('.' + CLASS.axisX + ' .tick text').each(function (e) {
-                var index = tickValues.indexOf(e);
-                if (index >= 0) {
-                    d3.select(this).style('display', index % intervalForCulling ? 'none' : 'block');
-                }
-            });
-        } else {
-            $$.svg.selectAll('.' + CLASS.axisX + ' .tick text').style('display', 'block');
-        }
+        $$.axis.updateCulling(tickValues);
     }
 
     // setup drawer - MEMO: these must be called after axis updated