Spinning Star Drawable
This project provides a sample of how to add an animated custom drawable to a toolbar.
A full guide explaining how to use and animate custom drawables can be found here: Custom Drawables and Animations
For the code take a look at SpinningStarDrawable
Indeterminate progress bar drawable
This sample also features a proof of concept for an indeterminate rectangular progress bar. This was used as a proof of concept for Modifying the resource image of Progress Bar
The code can be found here.