Please add alt_rgb_pins kwarg for RBG matrices

[PaintYourDragon]

Akin to the alt_addr_pins kwarg. Some matrices (including the 2.5mm pitch 64x64 from Adafruit) have green and blue swapped. This is already manifesting in the field, not a hypothetical situation:
https://twitter.com/firehoppr/status/1313180528556871682
https://forums.adafruit.com/viewtopic.php?f=60&t=170249&p=832142#p832142

[makermelissa]

It seems there is only RGB and RBG, so a flag to swap the order may make more sense. What do you think?

[PaintYourDragon]

Based on past experiences with RGB LED anything, a flag will come back to bite you later. Would recommend either a pin list, or accept a string like 'RBG', 'BGR' etc. and use the character positions (case-insensitive) to remap 'Portal pins.

[makermelissa]

Ok, cool. I like the option of adding an RGB order parameter. We can start with these 2 cases and add more as needed.

[PaintYourDragon]

Recommend just handling all the cases now. These matrices WILL change again and again, without announcement.

Dang I could SWEAR I had code for handling this in another project…oh, might’ve been the light painter or something…I’ll rummage around and get back to you!

[PaintYourDragon]

Starting around line 60 here:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/master/CLUE_Light_Painter/bmp2led.py

Huh. Could’ve sworn I had something that handled malformed cases better…but maybe that was something else, an older Arduino project, or I just dreamt the whole thing.

[makermelissa]

We can just check it r, g, or b is not found (-1) and just raise an error.