Emoji Limitations

Technical details on emoji rendering support and limitations.

Last updated: March 11, 2026

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) — Ebitengine cannot render color fonts
  • Apple Color Emoji — TrueType Collection format not supported by Go font libraries

Technical Background

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

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.

References