High speed / animation on Core 2 display

  • I have a python app that is monitoring the voltage of a rapidly changing signal (think audio amplitude) from a sensor and I am driving the width of a rectangle shape, modulating the width with the value of the signal. I would like to have a smooth update frequency of about 30 per second. Basically I want to emulate the look of old fashioned VU meters, either the electromechanical kind of the 60's or the LED bars of the 80's. I don't know the best way to do this. I.e. do I draw the rectangle, then erase it, then draw the new rectangle at the new width? I tried a couple of different approaches but they didn't look correct. Thanks.