Cascadia-code: Strange Stroke Overshot on certain font weights.

[flowchartsman]

Environment

Cascadia Code version number: 2009.14
Application (with version) used to display text: Fontbook
OS platform and version:

- Air: macOS Catalina 10.15.6 (19G2021)
- Pro Touchbar: macOS Mojave 10.14.6

Screen resolution:

- Air: 
  - Display Type: LCD
  - Resolution: 1440 x 900 (Widescreen eXtended Graphics Array Plus)
- Pro Touchbar:
  - Display Type: Built-In Retina LCD
  - Resolution: 2880 x 1800 Retina

Steps to reproduce

Horizontal strokes and a couple of joins seem to overshoot and look strange for certain glyphs and weights when I preview the font in fontbook before installation. This appears on both my old Macbook Air _and_ my newer Macbook Pro. (images attached)

Expected behavior

No Bulges

Actual behavior

Bulges

[aaronbell]

Thanks for the feedback! Out of interest, what does the font do in TextEdit after you’ve installed it?

[aaronbell]

So as far as I can tell, this is an issue with MacOS interpretation of variable fonts. I'd suggest using the static instances (either OTF or TTF) to achieve better rendering.

Thanks!

[aaronbell]

Sorry, I should clarify—macOS doesn't have an issue with variable fonts per se, but Cascadia Code happens to have outlines with coincident edges, thus causing the problem. This is unfortunately something that they should fix. As such, I have filed a bug report through their feedback tool.

[apodtele]

This confirms that macOS rasterizer is based on cumulative coverage, similar to FreeType.

[madig]

You may want to reopen this because https://github.com/microsoft/cascadia-code/pull/365#issuecomment-696395164 :D

[aaronbell]

Unfortunately the bug is still present even in the version with the correct flag set. So still Apple's problem :D