Just got my APA102 disk from @Adafruit_Industries
It certainly makes for one sexy display 
Working on circular pixel mapping in BiblioPixel right now… should’ve paid more attention to the part in math class about polar coordinates 
In my hour with it I can say it’s a pretty well built board and it’s so epically awesome that they (not Adafruit, it was built by SOYA LED out of China) used the APA102!
My only gripes are these…
The display has 255 pixels and the APA102 datasheet says 0.2W per pixel, so 51W/10.1A max draw. But all that is included for power is the 4 pin JST SM pigtail that has maybe 22AWG wire which is good for maybe 8A if you push it. I realize that that’s full bright and even then it’s unlikely to hit the specified max, but I just find that poor engineering.
Also, there’s another JST cable on the other end, but don’t think you can use that to supplement power… it’s only connected to ground 
Last… the JST cables are pre-soldered on to the front. Why would they not be soldered around back?
https://www.youtube.com/watch?v=JmxY-_dpIag
I’d imagine things are soldered onto the front so it will lay flat inside your project…? I really wanna play with one of these at some point so please do keep us posted on any coding hints!
You make a good point. Makes sense… but I want to place the front of the display up against a piece of semi-translucent acrylic.
As for coding, I’ve actually come up with a way to use radius and angle as pixel coordinates and have it in the v1.2 branch of BiblioPixel: https://github.com/ManiacalLabs/BiblioPixel/tree/v1.2
It is a little weird at first, but makes much more sense than trying to do (x,y) or index. You can specify a distance from the center and an arc path and it takes care of the mapping.
It’s still a work in progress, so any questions are welcome. Basically you just use the LEDCircle class instead of LEDStrip. I’ll upload examples soon.
I haven’t tried doing any of this directly from an Arduino w/ FastLED yet. I generally prototype with BiblioPixel which is python. You can use it directly from the SPI port on a Raspberry Pi with DriverAPA102 or from any computer with my AllPixel (http://maniacallabs.com/allpixel) controller board (which uses FastLED in the firmware) and DriverSerial.
I imagine the mapping I did for LEDCircle could be ported to use directly with FastLED. I’ll work on it.