# Sizzletracker (Android)

A retro, grid-based **music tracker** for Android — monospace UI, pixel icons,
demoscene-style pattern editing — playable equally with **touch, keyboard,
gamepad, and MIDI** (USB or Bluetooth).

<p>
  <img alt="platform" src="https://img.shields.io/badge/platform-Android%208%2B-0b0d0e">
  <img alt="language" src="https://img.shields.io/badge/kotlin-2.0-7cfc9a">
  <img alt="ui" src="https://img.shields.io/badge/UI-Jetpack%20Compose-f2c14e">
  <img alt="license" src="https://img.shields.io/badge/license-GPL--3.0--or--later-e05a4b">
</p>

📖 **[Full User Guide](docs/USER_GUIDE.md)** — a detailed, screenshot‑by‑screenshot
walkthrough of every tab, instrument, effect and control.

## Features at a glance

- **Tracker tab** — 4-track pattern grid (note / velocity-hex / MIDI-channel per
  track), beat & bar coloring, tap-to-focus + drag-to-edit with haptics and
  scale-aware note entry; plus an 8-lane arrangement piano-roll (up to 256 bars)
  with A/B loop regions.
- **Mix tab** — 4 channels, each with an instrument + 4 FX slots, MIDI channel,
  volume, mute/solo.
- **Toolbox tab** — 16 slots for instruments (3-oscillator synth, sampler, SF2/XI) and
  effects (arp, transposer, LFO, tape delay, reverb, filters, 10-band EQ,
  bitcrusher). Every device has an auto-generated editor and text presets.
- **Setup tab** — `.sng` project save/load, color themes (with import/export),
  gamepad bindings, and searchable/collapsible MIDI bindings.
- **Master recording** — render the master bus (with FX tail) to a WAV file.
- **Background playback** with a media notification (Play/Pause/Stop).
- **Two-thread design** — Compose UI on the main thread, a sample-accurate sound
  engine on its own high-priority thread.

There is also a standalone `tools/samplepack-builder.html` — an offline page for
assembling Sampler preset bundles (drop audio onto 16 note-labelled pads, then
download an importable `.zip`).

## Build & run

Open the project in **Android Studio** (2024.1+) and Run on an **API 26+**
device or emulator.

From the CLI (the Gradle wrapper is committed, so a fresh clone needs no setup):
```
./gradlew assembleDebug
```

## Where to start reading

See **[docs/DEVELOPER_HANDOVER.md](docs/DEVELOPER_HANDOVER.md)** — a from-scratch
tour written for a developer new to Android: architecture, the file map, the
"one action / one song / two threads" model, how to add an instrument or input,
and an honest **implemented-vs-TODO** list.

Fastest orientation in code:
`model/Project.kt` → `input/InputAction.kt` → `ui/AppViewModel.kt` →
`audio/AudioEngine.kt`.

## Project format

Songs use a human-readable `.sng` text format (see `io/ProjectIo.kt`), aligned in
spirit with the desktop
[Sizzletracker](https://github.com/reactorcoremeltdown/sizzletracker); a byte-exact
compatibility shim is a listed TODO in the handover doc.

## License

Sizzletracker is free software: you can redistribute it and/or modify it under
the terms of the **GNU General Public License v3.0 or later**
(`GPL-3.0-or-later`). See the [`LICENSE`](LICENSE) file for the full text; every
source file carries an SPDX `GPL-3.0-or-later` header.

Copyright © 2026 Reactorcoremeltdown