color-watcher (aka Ferrari Picasso)

Desktop app that will poll your screen for colors.

I started off sampling the entire screen and maping it into pixels in a webview.

So turning this:

into this:

And then I decided instead to only sample pixels around the border of the screen and then map those into an led strip! (but the led updates were slow b/c I was sending the data to the Arduino in a dumb way and updating the led strip had an annoying slow-updating raster-effect)

SO THEN! I decided to improve the I/O and add a slow color transition effect to really set the mood XD. Check out the YouTube video below:

and now I'm probably done writing c code for another decade :-P

Technical details / how it works

1. An electron app uses robotjs to scan some set of sample coordinates randomly in a loop visiting each sample-coord exactly once. In this case the sample coordinates are 80 pixels around the right, top and left border of the screen.
2. The electron app uses serial.js to send the color data along a usb port to an Arduino. The color data is 8-bytes encoded as such, [rgbi], where i is the index of a light on the led strip and rgb are the hex color values. Each value is encoded as a hex string. So all purple (max r and b) at pixel 5 looks like "FF00FF05".
3. The Arduino runs a loop that first looks for data on the serial buffer. It will split the message and pipe that data into uint32_t[] called stripBuffer. So that has to decode the hex colors into a uint32_t.
4. When there is no message available, it will then compare each index of stripBuffer to another uint32_t array called stripMemory.
5. If the color value at the index differs (between the buffer and the memory of the led strip) it will adjust stipMemory for each rbg value by the (difference / 10) || 1 (this is the fade transition), then will update the actual led strip with the value in stripMemory! :D