AS3 How to create a custom list item renderer with image(base64 png string) at runtime

I'm a newbie to Flex. I'm trying to create a list with icons. Ther开发者_开发问答e're a lot of examples but seems all of them are using embedded images. My problem is how can I create the list with icon from base64 png string at runtime?

Use the Base64Image from flexlib (first item in that component list) with this as an example.