Hello,
Starting a topic on cpctelera_next development of geometry API. I hope Arnaud will create a real post on CPCTelera_Next soon.
I saw that Mode 1 geometry was added with support of Line and Circle last months.
I have started a small contribution to it by creating fast Horizontal lines, mainly to add a FillScan in future (and filled circle if possible). I also created a getColorAt that I will need.
If Arnaud can tell me if I can push it. 
Hello,
i just come back, and i will create a post on CPCTelera_next, to sum up all work done.
Yes, i have worked a lot on drawing line (here some video of work versions : https://www.youtube.com/@arnaudbouche7887). Thanks @ervin for his hard work on drawing lines, I picked up a lot of good ideas from his code.
Filling shape is in the todo list, you are welcome if you want to work on fillRect, fillCircle or fill what you want.
UPDATE : here the new post CPCteleraNext framework - #2 by Arnaud6128
Oooh nice one. That was always the biggest pain of generating plus sprites. They were complete mares to do from scratch.