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README.md

Atomic Canvas

  • An android app note taking / infinite canvas drawing / vector app with pen & draw support
  • Extremely snappy, no-nonsense
  • Uses a CRDT (Loro) to sync notes and brush strokes. Full history playback and versioning.
  • Uses modern android standards and APIs. research conventions.
  • Easy & fast management with folders
  • Smart gestures, controls, pen support
    • if using a pencil, fingers pan (single finger drag) & undo (double finger tap) & select (single finger hold)
    • if using fingers, fingers pan, but user can quickly toggle draw mode
    • Manu items have hold & drag interactions for fast gestures
  • Simple, clean, minimal UI, a couple of buttons at the buttom:
    • Tutorial (starts tutorial, shows UX)
    • Color selector (drag, a fan pops up, let go to select color. Tap to go back to previous color)
    • Size adjust (same UX: drag & hold to select, tap to go to previous)
    • History scrubber. Tap to undo, scrub to navigate history. You can even open "forgotten" branches of undo history, so nothing is ever lost
    • New canvas button
    • Gallery / back
    • Eraser
    • Reset view /zoom scrubber (tap to fit all content, or tap again to go back to previous view)
    • Place image

Development

This project uses mise to manage the Flutter SDK (Flutter 3.44+, Dart 3.12 — see .mise.toml).

A Makefile wraps dev.sh which sets up a FIFO pipe so you can trigger hot reload from any terminal tab — no need to switch focus or type into the running process.

Starting dev servers

Run each device in a separate terminal (they share build/, so don't start them simultaneously):

# Terminal 1
make tablet     # Samsung SM X810 tablet

# Terminal 2 (after tablet finishes building)
make phone      # Pixel phone (456cb10b)

make web        # Chrome (separate terminal)

Logs

Output is captured to logs/<target>.log (truncated on each launch):

grep "error" logs/tablet.log
grep "iroh" logs/phone.log

Hot reload (from any terminal)

make reload-tablet    # Hot reload
make restart-tablet   # Hot restart
make reload-all       # Reload all running targets
make restart-all

Other

make analyze    # Static analysis

To update the Android device IDs, edit dev.sh (ANDROID1_ID = tablet, ANDROID2_ID = phone).

Sync / Pairing

Devices sync via Iroh (QUIC peer-to-peer, works through NAT).

  • Open Settings > Pair with QR Code
  • Device A shows its QR code, Device B scans it (or vice versa)
  • Sync is bidirectional — both devices exchange data regardless of who initiates

NodeIDs are persistent (stored in the local DB), so a QR code stays valid across app restarts.

Zoom / pan

Input Action
Trackpad pinch Zoom
Ctrl + scroll Zoom
Two-finger scroll Pan
Middle mouse drag Pan

Stylus / pen input

When a stylus or pen is detected, finger touches pan the canvas instead of drawing. This matches the behaviour of the Kotlin version: use the pen to draw, fingers to navigate.

Architecture

The Dart client code in lib/atomic/ (AtomicClient, session.dart, FRB bridge) is not canvas-specific — it's a general-purpose Atomic Data SDK wrapping atomic_lib via flutter_rust_bridge. Once the API stabilizes, it should be extracted to atomic-server/dart/ (or sdk/dart/) as a reusable Dart package, keeping this app as a thin UI layer on top.