Backport Font

Convert a modern color font into a renamed, JVM-compatible variant.

The default configuration converts the system Noto Color Emoji (which uses COLR v1) into Noto Color Emoji Compat (COLR v0), so PHPStorm, IntelliJ, and other JetBrains IDEs on Fedora Silverblue can render color emoji. Every option is overridable, so the same tool works for any color font.

TLDR

Just copy any .ttf (or .otf) file like the one found at dist/NotoColorEmojiCompat.ttf into:

Your user only: ~/.local/share/fonts/ All users (needs sudo): /usr/local/share/fonts/

fc-cache -f

What it does

1. Copies the source font into build/source/ (never modifies the system file).
2. Rewrites the name table so the output advertises a new family name.
3. (When the source uses COLR v1) flattens the v1 paint graph into a v0 layer list — solid layers from gradients are picked at the dominant stop, affine transforms are baked into the layer outlines (so flips, scales, and translations are preserved, not lost), composites degrade to their content-bearing child, and palette references are preserved verbatim. Adjacent same-color layers are merged so the whole font fits COLR v0's layer budget without dropping anything.

Why

PHPStorm (and other JetBrains apps using JetBrains Runtime) ship a Java2D font path that doesn't render COLR v1 — gradients and paint graphs aren't supported. COLR v0 (a flat list of layered glyphs colored by palette index) is widely supported. The tool produces a font that's visually similar enough for emoji rendering while staying within COLR v0.

The renaming step is needed because Java2D and fontconfig will otherwise prefer the system's COLR v1 font and fall back to colorless rendering.

Setup

Run on Fedora Silverblue. A toolbox is recommended but not required, as long as Python 3.11+ is available.

make setup     # creates .venv and installs fonttools, brotli, lxml

Build & install

make build     # produces build/output/NotoColorEmojiCompat.ttf
make install   # copies to ~/.local/share/fonts/ and runs fc-cache

A pre-built copy is committed at dist/NotoColorEmojiCompat.ttf, so users who don't want to run the toolchain can install directly:

cp dist/NotoColorEmojiCompat.ttf ~/.local/share/fonts/
fc-cache -f ~/.local/share/fonts/

After install, point JetBrains at the new family. In PHPStorm:

• Settings → Editor → Font → Fallback font → Noto Color Emoji Compat
• Restart PHPStorm so the JVM rebuilds its font cache.

If emoji still don't render, JetBrains Runtime may also need a refresh: delete ~/.cache/JetBrains/<product>/fontcache and restart.

Use with a different font

Every default is overridable:

# Convert a custom font:
make build INPUT=/path/to/MyEmoji.ttf NAME="My Emoji Compat" \
           OUTPUT=build/output/MyEmojiCompat.ttf

# Or call convert.py directly:
.venv/bin/python convert.py --input MyEmoji.ttf --name "My Emoji Compat" \
                            --output out.ttf --mode colr-v0

Modes:

• auto (default) — pick colr-v0 if the input has COLR v1, otherwise rename-only.
• rename-only — just rewrite the name table.
• colr-v0 — also downgrade COLR v1 → v0.

Update workflow

When Fedora pushes a new google-noto-color-emoji-fonts package:

make check     # compare installed source vs. last-built version
make install   # rebuild and reinstall if needed

Layout

convert.py                # main entry point
scripts/
  inspect_font.py         # dump name, color tables, glyph stats
  rename_font.py          # rewrite name table
  downgrade_colr.py       # COLR v1 → v0
  check_upstream.py       # compare versions
dist/
  NotoColorEmojiCompat.ttf  # pre-built release artifact (OFL 1.1)
  OFL.txt                 # license bundled with the font
build/                    # gitignored scratch dir for builds
docs/
  source-font-info.txt    # snapshot of the input font's structure
LICENSE                   # MIT — applies to source code only
OFL.txt                   # SIL OFL 1.1 — applies to all .ttf files

Known limitations

• Gradients are flattened to a single dominant color — output will look flatter than the original.
• Blend/clip composites (e.g. soft-light shading, src-in masks) can't be represented in COLR v0, so the overlay is dropped and the underlying content is kept. The emoji is recognizable but loses subtle shading.
• Affine transforms are baked into per-layer outlines by generating transformed copies of the source glyphs. This grows the glyph count (which is also a uint16, capped at 65535) but keeps placement correct.
• Adjacent same-color layers are merged losslessly to stay within COLR v0's 65535-layer-record budget; truncation only kicks in if a font still overflows after merging (Noto does not).

Credits

This project is a derivative of Noto Color Emoji by Google LLC. All glyph artwork, palette data, and outline data in the output font come from the upstream Noto Color Emoji release shipped in the Fedora google-noto-color-emoji-fonts package. This tool only rewrites the font's name table and rebuilds its COLR table at version 0.

• Upstream font: https://github.com/googlefonts/noto-emoji
• OFL 1.1 license: https://openfontlicense.org/
• OFL 1.1 FAQ: https://scripts.sil.org/OFL-FAQ_web

License

This repository contains two distinct kinds of artifacts under different licenses:

• Source code (Python scripts, Makefile, documentation) — MIT.
• Font files (dist/*.ttf and any .ttf produced by make build) — SIL Open Font License 1.1. This is required: the output font is a derivative of Noto Color Emoji, which is OFL-licensed. The output font preserves Google's original copyright and OFL notices in its name table (ids 0, 7, 13, 14).

If you redistribute the .ttf (e.g. bundle it inside another project), you must include OFL.txt alongside it, as required by OFL clause 2.

Trademark notice

"Noto" is a trademark of Google LLC. The output font's name retains "Noto" because the SIL OFL 1.1 license terms attached to the upstream font do not declare any Reserved Font Names — see clause 3 of OFL and confirm against the upstream LICENSE. This does not grant trademark rights.

This project is not affiliated with, endorsed by, or sponsored by Google. It is an independent compatibility shim built for use with PHPStorm and other JVM-based applications.