Performance improvement for draw functions

[MightyJosip]

Fix #2517

This is kinda big refactoring of draw module, function changed are single pixel line thickness, arc, circle, ellipse, triangle, and multi pixel thick rectangle. Most of those functions should see solid performance boost (depends on the function). I didn't change circle quadrant (and corresponding round rect), it needs big refactoring, and right now I don't want that to be roadblocker to this. Also I don't think I could accomplish much with thick line

[Starbuck5]

Hey MightyJosip!

I'm just starting to look at this and it's a lot of lines changed, I think it would be helpful if you explained the rationale behind what you've done. I see you've linked #2517 but it seems like what you've done here is more complex than what MyreMylar pointed out.

You say that functions "should" see a speedup, have you done any performance testing?

[Starbuck5]

Ok I'm starting to see the approach now, you've used heavy use of ## macro syntax to conditionally select functions so whole paths are specific to bit depth.

This is not a strategy I've used before. In the blitter code my strategy was to pass code as a parameter argument into macros.

Before this PR, the draw module is 52.5kb, afterwards it is 86.5 kb.

[Starbuck5]

Ok I might be up to speed now. Myre was talking about function pointers in heavy loops on discord (that must've been your previous strategy), so now you've done it so that the code path is duplicate-compiled farther up. Now I look at it and one of my first impressions is that it's excessively duplicated.

Maybe this is what we get to eventually or maybe there is a better way? I'm not sure.

[itzpr3d4t0r]

Yeah an actual reproducible program and results would make things easier.

[MightyJosip]

Yeah an actual reproducible program and results would make things easier.

Based on the @MyreMylar test in the issue: https://gist.github.com/MightyJosip/dca7901bb48f053bdb10e0f23244afa1 (file test.py)

Tested on current release (2.3.2) and my branch. TLDR of the results

Function tested	Newest release	My branch
Draw Small Line	0.735	0.596
Draw Big Line	0.803	0.450
Draw Small Arc	3.181	2.487
Draw Big Arc	9.893	7.395
Draw Small Thick Circle	4.125	3.820
Draw Big Thick Circle	14.773	14.331
Draw Small Circle 1 width	1.362	1.159
Draw Big Circle 1 width	2.485	1.440
Draw Small Filled Circle	1.222	1.220
Draw Big Filled Circle	14.795	13.881
Draw Small Ellipse	1.368	1.219
Draw Big Ellipse	9.893	9.354
Draw Small Filled Ellipse	0.613	0.588
Draw Big Filled Ellipse	9.365	9.205
Draw Small Thick Rect	0.835	0.818
Draw Big Thick Rect	8.064	8.075
Draw Small Filled Triangle	0.242	0.219
Draw Big Filled Triangle	18.950	18.270

[itzpr3d4t0r]

This optimization effort is truly impressive and worth celebrating. However, the number of changes and the effort needed to review them make it quite challenging. Since these are mostly macro compositions, it's hard to follow and review them properly. I'm also worried that future improvements will be difficult.

Could we split this into multiple pull requests? For example, one for lines, one for circles, and so on. This would make it easier and faster to review, test, read, and suggest improvements. Let me know what you think.

[bilhox]

This optimization effort is truly impressive and worth celebrating. However, the number of changes and the effort needed to review them make it quite challenging. Since these are mostly macro compositions, it's hard to follow and review them properly. I'm also worried that future improvements will be difficult.

Could we split this into multiple pull requests? For example, one for lines, one for circles, and so on. This would make it easier and faster to review, test, read, and suggest improvements. Let me know what you think.

Hello @itzpr3d4t0r , I was also thinking about the same thing when I was reading the changes. I'm also seeing 2 PR (this one and #2080) with the same objective. IMO we should open an issue about general draw performance improvements, and link these 2 PRs to the issue, so if anyone else want to work on it, he can see the work of joking and temmie.

Let me know what you think @MightyJosip and @Temmie3754 .