hfg-gmuend/openmoji

OpenMoji-Color fonts incompatible with WinAPI.

Open

#478 opened on Dec 1, 2023

View on GitHub
 (2 comments) (0 reactions) (0 assignees)HTML (3,504 stars) (203 forks)batch import
help wanted

Description

For MS Windows Software, the common (also simplest) way to use Color Fonts with API (DirectWrite) is: "To opt in to color glyph rendering, pass the D2D1_DRAW_TEXT_OPTIONS_ENABLE_COLOR_FONT" This works with several fonts (Segoe UI Emoji, Twemoji Mozilla, EmojiTwo COLRv0, Noto Color Emoji). But with OpenMoji, the text never shows OpenMoji glyphs, but only fallback-glyphs (if available) from Segoe UI Emoji. The big FOSS software (Browsers, Libre Office) use other libraries which don't have this problem. But typical app developers use DirectWrite or components based on DirectWrite. DirectWrite officially supports COLR (v0, v1) and some other formats. There must be some solution to generate the font file (eg. COLRv0) compliantly,
but I have no knowledge about file details and potential modifications or tools.

Contributor guide

Tech stack
None
Domain
apidesktop
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
Understanding of COLR font formatFamiliarity with DirectWrite APIKnowledge of font generation tools
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Investigate the OpenMoji font file structure and compare with working fonts like Segoe UI Emoji or Noto Color Emoji. Check if the font uses COLRv0 or v1 and whether any flags or tables are missing. Look at tools like fonttools (Python) to inspect and potentially modify the font. Review any existing issues or documentation about OpenMoji font generation pipeline in the repository.