various screen fixes

[tehn]

fixes #412

fixes #410

fixes #395

also adds screen.pixel(x,y) (lua)

[tehn]

@markwheeler

[tehn]

added one more fix to menu display

fixes #416

[tehn]

so i think i got everything. unfortunately you don't have hardware at the moment to check!

[markwheeler]

Ha yep, actually I don't have the build environment setup anyway (only been doing lua and sc stuff so far).

Looking at the code the fixes look like they make sense.

However I would suggest also removing the half pixel offset from screen_arc, screen_rect, screen_move and screen_line. The offset only really makes sense if you are drawing with an odd-width stroke which seems like a confusing assumption to make. Thoughts?

[tehn]

FYI the dev chain is all built in on norns. to recompile:

cd norns
git pull
./waf
./stop.sh
./start.sh

and you'll be up and running.

perhaps i'm misunderstanding cairo--- i added the offsets after some googling as a result of initial weird rendering issues.

is pixel 0,0 translated as the area between (-0.5,-0.5) and (0.5,0.5) or is it (0,0) to (1,1)?

looking for references now...

[markwheeler]

I think this explains it: https://www.cairographics.org/FAQ/#sharp_lines

and good to know about the recompiling thanks!

[tehn]

thanks for the link, that was the one i read way in the past and had forgotten.

so you imagine it's best to let users figure out the offset business on their own? as the current hack isn't a real solution clearly.

[markwheeler]

Oh I didn't answer your earlier question: When Cairo draws a 1px rect with top left at '0,0' it is exactly filling the first pixel, which could be described as the area from 0-1 on a graph.

Yes I think if we stick to the default cairo way of doing things we'll at least be in alignment with how most screen drawing systems work. And yep I'm sure some folks will draw 1 pixel lines and wonder why they're blurry but at least when they end up at that link or similar it'll get them on track!

Of course this change will throw off some of the current UI, we'll have to do a pass to see what needs tweaking.

[tehn]

checking the UI now. rect is really off with integers using stroke so i'm offsetting the LEVELS page with the bars. other scripts with normals lines seem fine ie awake and playfair

[markwheeler]

Hmm I would have expected any on-pixel line drawing to now need to be shifted on the script side (eg, in awake) in order to stay sharp. Think I need to test this on device! :D

[tehn]

Hmm I would have expected any on-pixel line drawing to now need to be shifted on the script side (eg, in awake) in order to stay sharp. Think I need to test this on device! :D

i expected it as well, but playfair and awake look identical to as before.

[tehn]

scratch that... almost identical. there's some off-by-one pixel tuning now but it's minor

[tehn]

i think this is good to merge if you (or anyone) would like to approve the PR

[pq]