RLE format, save, open & create pictures with CLI commanded.
Works on linux and windows (rewritten and tested in Ubuntu 20.04.4)
To compile with GCC:
makeExample of generated picture:

Command list:
open_rle file_path
open_txt file_path
save_rle file_path
save_txt file_path
create_square size regular/invert
create_triangle size regular/invert
create_romb size regular/invert
print
exit
help