macvim-dev / macvim-dev/macvim
CoreText garbles ligatures
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Description
Snapshot 134, macligatures is enabled. The font I am using is PragmataPro. It's hard to describe what I am experiencing, so let's have a look at two gifs.
Here is entering !== without CoreText:
As you can see, everything looks fine. Here is the same with CoreText enabled:
As you can see, something is quite off here. The ligature gets broken somehow during working on the line. However, when changing the line, everything looks normal. Obviously, disabling CoreText is a perfect workaround, but since scrolling performance is somewhat horrible, I'd love to know if there is anything anyone can do here to resolve this rendering weirdness.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the issue with CoreText and macligatures enabled, using PragmataPro and entering !==; compare the behavior with CoreText disabled. Done means ligatures remain correctly rendered while editing and scrolling performance is not regressed.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- macos, vim
- Domain
- desktop, performance
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100