I actually made the first version if this program a long time ago, before I became active in the community. I remade it a few nights ago and uploaded it to TICalc, but it basically works like this:
-Give it a list of coordinates and types
-It generates a hex opcode that draws the rectangles with the given coordinates and methods.
It takes input in the form of {x,y,width,height,type} and you can give it multiple rectangles. It does 6 rectangle types, including the typical black/white/invert, using OS bcalls. This is also a BASIC program that generates the opcodes. As well, it tries to optimise the opcode a little, so if there are 8 or more rectangles, it uses a different method of drawing them (generating an array of coordinates/types and reading them, using 29 bytes extra overhead, 4 bytes less for each rectangle).
Anyways, it was useful for me when I was working on BASIC RPGs to make an assembly program that drew a map. The download is below. With so many other tools available now, this type of program is a bit outdated