Yii Custom Widget

I am trying to create a Yii widget that will generate Google Cha开发者_运维技巧rts (http://code.google.com/apis/chart).

How do I make a widget that writes code in both the html headers (where the javascript includes and stuff will be), and in the html body?

I found my answer:

Yii::app()->clientScript->registerScriptFile()

and

Yii::app()->clientScript->registerScript()