head table bounding box is not recalculated for variable font instances

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#40 4 comments 0 reactions 0 assignees View on GitHub

@khaledhosny is already working on this.

Since Oct 29, 2026.

  • #41 by @khaledhosny — open

Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
56/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
rust
Domain
backend

Research direction

Start by reading subset_with_variations() and the code that writes the OpenType head table; the issue does not name files or tests. Check how the default instance's bounds are copied and whether existing variation tests cover the table. Done means the instantiated font's xMin, yMin, xMax, and yMax include its glyph bounds, preventing macOS rasterizer cropping.

Written by the indexing model from the issue text.

Description

Using subset_with_variations() to instance of a variable font, it does not update the head table bounds (xMin, yMin, xMax and yMax are copied unchanged). Some glyphs in the instance might be bigger than the bounds of the default instance.

The macOS rasterizer crops glyphs outside of the head bounds. This can be seen when opening PDFs created with Krilla in macOS Preview (I had the same issue in PDFs created with Illustrator previously).

Dominant language
Rust
Stars
61
Forks
16
No merged PRs in 30d

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