Fixes #1192

src/api.tooltip.js

@@ -28,8 +28,12 @@ c3_chart_fn.tooltip.show = function (args) {
     // emulate mouse events to show
     $$.dispatchEvent('mouseover', index, mouse);
     $$.dispatchEvent('mousemove', index, mouse);
+
+    config.tooltip_onshow.call($$, dataToShow);
 };
 c3_chart_fn.tooltip.hide = function () {
     // TODO: get target data by checking the state of focus
     this.internal.dispatchEvent('mouseout', 0);
+
+    config.tooltip_onhide.call(this);
 };

src/config.js

@@ -192,6 +192,8 @@ c3_chart_internal_fn.getDefaultConfig = function () {
         tooltip_init_show: false,
         tooltip_init_x: 0,
         tooltip_init_position: {top: '0px', left: '50px'},
+        tooltip_onshow: function () {},
+        tooltip_onhide: function () {},
         // title
         title_text: undefined,
         title_padding: {