Android: How can I write a custom ImageView with Progress?

I have a lazy image loader, and would like to have a custom ImageView that shows progress while the image is loading. I'm just not sure how to achieve this. I know it must be a compound control, but I'm not sure how to do it. The behavior I want is to show an indeterminate p开发者_运维百科rogress in place of the image, until the image loads. Any help is appreciated.