Draw a keycap emoji as one keycap glyph #32

Merged

natsukium merged 1 commit from fix/keycap-vs16 into main

2026-10-06 16:03:56 +09:00

natsukium commented

2026-10-06 14:49:46 +09:00

Owner

Closes #30.

A keycap emoji (#️⃣, 1️⃣) drew as a tiny # beside an empty keycap. swash 0.2.10 drops VS15/VS16 only after an emoji base; after # it shapes the VS16 as a .notdef with a full advance, which sits between # and U+20E3 during GSUB and splits the font's keycap ligature into three glyphs. The cluster fit then shrank all three into two cells.

Shaper::shape_cluster now shapes the cluster without the variation selectors (U+FE00..FE0F, U+E0100..E01EF) that the chosen face does not map; the base is always kept, and a selector the face maps directly stays.

The presentation selectors have already done their job by picking the face.
swash never consults the cmap's variation-sequence subtable, so an ideographic variation selector cannot pick its variant today either; dropping it changes no glyph. The code comment and text-shaping.md name the revisit trigger (swash gaining variant mapping).

Tests: the keycap shapes to the same single glyph as #⃣ on the emoji face (three glyphs [4, 0, 21] without the fix); a keycap cell needs no fit (fit_px 5 without the fix, 0 with it); a unit test covers the filter (IVS, FE00, mapped selector, lone selector).

Before (top) / after (bottom), offscreen render with Moralerspace Neon HW: the keycaps reach full size; ❤️ ⭐︎ 👍🏻 and 葛󠄀 ≩︀ are unchanged.

Closes #30. A keycap emoji (`#️⃣`, `1️⃣`) drew as a tiny `#` beside an empty keycap. swash 0.2.10 drops VS15/VS16 only after an emoji base; after `#` it shapes the VS16 as a `.notdef` with a full advance, which sits between `#` and U+20E3 during GSUB and splits the font's keycap ligature into three glyphs. The cluster fit then shrank all three into two cells. `Shaper::shape_cluster` now shapes the cluster without the variation selectors (U+FE00..FE0F, U+E0100..E01EF) that the chosen face does not map; the base is always kept, and a selector the face maps directly stays. - The presentation selectors have already done their job by picking the face. - swash never consults the cmap's variation-sequence subtable, so an ideographic variation selector cannot pick its variant today either; dropping it changes no glyph. The code comment and `text-shaping.md` name the revisit trigger (swash gaining variant mapping). Tests: the keycap shapes to the same single glyph as `#⃣` on the emoji face (three glyphs `[4, 0, 21]` without the fix); a keycap cell needs no fit (`fit_px` 5 without the fix, 0 with it); a unit test covers the filter (IVS, FE00, mapped selector, lone selector). Before (top) / after (bottom), offscreen render with Moralerspace Neon HW: the keycaps reach full size; ❤️ ⭐︎ 👍🏻 and 葛󠄀 ≩︀ are unchanged. ![before and after](https://git.natsukium.com/attachments/ebab2f1a-97f0-49d5-87f5-34551d2fbb8f)

compare30.png

18 KiB

natsukium added 1 commit

2026-10-06 14:49:46 +09:00

shaping: drop variation selectors the cluster's face does not map

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041cfbd4c0

A keycap emoji (#️⃣, 1️⃣) drew as a tiny `#` beside an empty keycap.
swash 0.2.10 keeps a variation selector that follows a non-emoji base as
a shaping character, maps it through the cmap to glyph 0, and leaves
that .notdef between `#` and U+20E3 during GSUB, which splits the font's
keycap ligature into three glyphs; the cluster fit then shrank all three
into two cells.

shape_cluster now shapes the cluster without the selectors (FE00..FE0F,
E0100..E01EF) the chosen face does not map. The presentation selectors
have already done their job by picking the face. swash never consults
the cmap's variation-sequence subtable, so an ideographic variation
selector cannot select its variant either, and dropping it changes no
glyph while keeping it out of ligature lookups. A selector the face maps
directly is kept, so the rule follows the face's coverage, not the text.

Closes #30

Assisted-by: Claude Code