testsAndMisc/python_pkg/app_icons

app_icons — shared launcher icons for the Flutter apps

One icon family across every Flutter/Dart app: a charcoal #211D1B field with a single glyph in the shared unified-design-system accent (#B8862E), drawn at one stroke weight and optically centred so a row of them lines up.

Commands

# what is registered
PYTHONPATH=~/src/testsAndMisc python3 -m python_pkg.app_icons list

# contact sheet for visual review: full size / circle-masked / 48dp
PYTHONPATH=~/src/testsAndMisc python3 -m python_pkg.app_icons preview -o /tmp/sheet.png

# write assets into every app repo and rebuild the Android mipmaps
PYTHONPATH=~/src/testsAndMisc python3 -m python_pkg.app_icons generate --android

# one app, plus the hicolor PNGs for a Linux desktop target
PYTHONPATH=~/src/testsAndMisc python3 -m python_pkg.app_icons \
    generate --app todo --android --linux-out ~/src/todo/linux/icons

# overwrite web/favicon.png + web/icons/Icon-*.png (apps with a web/ dir);
# the maskable ones are safe because INK_RADIUS (340px) sits inside the 40%
# (410px) maskable circle
PYTHONPATH=~/src/testsAndMisc python3 -m python_pkg.app_icons \
    generate --app tutor --android --web

What gets written

Per app, into <repo>/assets/icon/:

Layer	Purpose
icon	Charcoal field + glyph. Legacy square launcher icon and Linux icon.
icon_foreground	Glyph only, transparent. Adaptive-icon foreground layer.
icon_monochrome	Glyph only, white. Android 13+ themed icons.

Both an .svg source and a 1024px .png are written for each, so a build never needs rsvg-convert. flutter_launcher_icons then turns the PNGs into the density buckets and mipmap-anydpi-v26/ic_launcher.xml.

Design constraints that bite

• Negative space ≥ half the stroke weight. Strokes closer than that merge into a solid blob at launcher size. A fork whose tines sat exactly one stroke width apart rendered as a tulip.
• Every glyph fills the same circle. fit.placement centres the ink and scales it so the furthest inked pixel sits style.INK_RADIUS (340px, 24.4dp) from the centre; the stroke width is divided by the scale so strokes stay 72px. Check negative space at that final scale, since big drawings shrink.
• Stroked outlines can read wrong. A stroked three-tine fork reads as a trident; a filled fork-and-knife pair reads as cutlery. Prefer a filled silhouette when the outline is ambiguous.
• Glyph position and size inside the fragment are irrelevant. Only the shape matters.
• Launcher names live in labels.py: a capital first letter, ASCII letters only, ≤ 10 chars and ≤ 522 wide in the launcher font (_label_widths.py), because the Pixel app drawer cuts wider names.

Adding an app

See the app-icon skill (~/.claude/skills/app-icon/SKILL.md) for the full procedure. In short: add a glyph to glyphs.py, register the app in apps.py, wire flutter_launcher_icons into its pubspec.yaml, generate, review the contact sheet, then verify on the phone.

Tests

cd ~/src/testsAndMisc
python3 -m pytest python_pkg/app_icons --cov=python_pkg.app_icons \
    --cov-report=term-missing

External tools (rsvg-convert, magick, dart) are mocked; the suite needs none of them installed.