Emoji Rendering Limitations

Summary

Full-color emoji rendering is not supported in zurm due to Ebitengine limitations. However, monochrome emoji outlines are now available via the font fallback chain using Noto Emoji.

What Works

Monochrome emoji via NotoEmoji-Regular.ttf as a fallback font — renders black-and-white outlines
CJK characters via Noto Sans Mono CJK fallback
Nerd Font symbols (powerline, devicons) via Symbols Nerd Font fallback
Multiple fallbacks can be chained in config.toml [font] fallbacks

What Doesn’t Work

Color emoji (multi-colored glyphs like 😀🎉🔥) — Ebitengine cannot render color fonts
Apple Color Emoji — TrueType Collection format not supported by Go font libraries
ZWJ sequences (👨‍👩‍👧‍👦, 🏳️‍🌈) — require complex text shaping not available in Go
Skin tone modifiers (👋🏽) — modifier codepoints not combined
Flag sequences (🇨🇦, 🇺🇸) — regional indicator pairs not rendered as flags

Technical Background

Ebiten Limitation: The Ebiten game engine doesn’t support color fonts (Issue #2649)
Go Font Library: The golang.org/x/image/font package returns ErrColoredGlyph when encountering color glyphs
No Native Bridge: Pure Go programs cannot easily access platform-native text rendering (CoreText on macOS, DirectWrite on Windows)

Workarounds

Use Nerd Font symbols for icons in your prompt — they render perfectly as single-codepoint glyphs
Use monochrome emoji (outlined/black-and-white) via NotoEmoji fallback font
For programs that display emoji (e.g., npm, yarn), the outlines are readable even without color

Setup

Add fallback fonts to ~/.config/zurm/config.toml:

[font]
fallbacks = [
  "~/Library/Fonts/NotoSansMonoCJKsc-Regular.otf",   # CJK
  "~/Library/Fonts/NotoEmoji-Regular.ttf",           # monochrome emoji
  "~/Library/Fonts/SymbolsNerdFontMono-Regular.ttf", # powerline + devicons
]

Download commands are in the config template comments.

Emoji Limitations