[206_19]: Fix Latin Modern Math cannot input "h" in math mode#2865
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da-liii merged 1 commit intoMoganLab:mainfrom Feb 26, 2026
Merged
[206_19]: Fix Latin Modern Math cannot input "h" in math mode#2865da-liii merged 1 commit intoMoganLab:mainfrom
da-liii merged 1 commit intoMoganLab:mainfrom
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Map lowercase 'h' to U+210E (PLANCK CONSTANT) instead of the unassigned U+1D455 in smart_font_rep::advance(). Add corresponding reverse mapping in init_unicode_substitution(). Fixes MoganLab#2742
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Pull request overview
Fixes math-mode input/rendering of lowercase h when using OpenType math fonts like Latin Modern Math by mapping the character to the correct Unicode code point (U+210E) and ensuring reverse substitution remains consistent.
Changes:
- Add a Unicode substitution mapping for U+210E (ℎ) →
'h'underitalic-math. - Special-case
smart_font_rep::advance()to map math italic'h'to U+210E instead of the unassigned U+1D455. - Add a developer note documenting the issue, root cause, and manual test steps.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| src/Graphics/Fonts/smart_font.cpp | Implements the forward mapping (h → U+210E) and adds reverse substitution for U+210E in the Unicode substitution table. |
| devel/206_19.md | Documents the bug, rationale (U+1D455 unassigned), and verification steps. |
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Here is the behavior after the fix: |
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Fixes #2742
Problem
When the math mode font is set to Latin Modern Math, typing "h" in math mode produces no output.
Root Cause
In
smart_font_rep::advance(), lowercase letters are mapped to Unicode Mathematical Italic codepoints via a simple offset:0x1D44E + (s[0] - 'a'). For 'h', this computes U+1D455 — but U+1D455 is intentionally unassigned in the Unicode standard. The correct math italic small h is at U+210E (PLANCK CONSTANT) in the Letterlike Symbols block. Since Latin Modern Math (and all conforming OpenType Math fonts) has no glyph at U+1D455, the character fails to render.Fix
smart_font_rep::advance()to map 'h' → U+210E instead of the unassigned U+1D455U+210E → 'h'ininit_unicode_substitution()for consistencyHow to Test
Developer document:
devel/206_19.md