dorado-hd/docs/apps/drummachine.md

Drum Machine

• Official package: DrumMachine.exe (drums)
• Corpus: Zune HD Apps (Decompiled)/drums (external, untracked)
• Wave: W1 · Category: music
• Status: native · Complexity: TBD
• Dorado-HD id: drummachine

Synthesized from the decompiled reference. No Microsoft code, strings, or assets are copied; behavior is re-derived and all content is re-authored.

1. Device behavior (mined)

DrumMachine.exe is a third-party (DiNoGames, Dirk Nordhusen) 22-type / 169-method drum pad and pattern sequencer (4,356 lines). Pads are freely placed on a 272×480 stage; each pad can layer two samples, loop while held, and be recorded into a timestamped pattern that plays back over the stage. A metronome, an arrange mode with three presets, a runtime configuration dialog and an options dialog round it out.

Assembly	Types	Methods	Source lines
DrumMachine.exe	22	169	4356

Game1 owns the drum list, texture set, GUI controls, dialogs, recorded pattern and playback state; Drum owns hit geometry, sample layering and loop retrigger; Dialog + TouchButton/TouchSlider/TouchCheckBox/ TouchRadioButton are a small immediate-mode widget kit; DiscoLight/ LightCone drive the animated stage lighting.

2. Screens & navigation

There is one play screen plus overlay dialogs (DrumMachine!Dialog.Show / Hide; dialogs draw through 512×512 render targets and grab input while open). The screen has a fixed top-right config button, and the DrumMachine!Menu slides in from the right edge with entries Arrange, Record, Configure, Options, Metronome, Info and Hide (Menu.ArrangeMenuEntryExecute … HideMenuEntryExecute). Arrange mode shows three preset buttons (1/2/3), the OK button and a zoom slider. Record mode shows Stop while recording; Play mode runs the captured pattern. Game1.SetArrangeMode / RecordButtonExecute / StopButtonExecute / PlayButtonExecute / OKButtonExecute are the mode transitions; each mode shows or hides the relevant controls, so navigation is menu-driven rather than a page stack.

3. Rules, scoring & progression

• Pads. Drum.ChangeType binds a DrumType (Kickbass, Tom, Snare, HiHat, Crash, Ride, Misc) to a texture, default sample, layer depth and hit zones. Drum.PointOnDrum hit-tests the scaled collision rectangle against the texture's own alpha (transparent pixels do not hit).
• Layered sounds. Every pad exposes Sound1/Sound2. Zone logic keys on the hit point: Kickbass/Tom/Snare/Crash/Misc split at position.X + 15 for loop switching, HiHat hits right of the split play Sound2 (closed) and left play Sound1 (open), and Ride uses a radial 40·size split between bell and edge. Drum.Play(1|2) dispatches the matching SoundItem.
• Looping. With DoLoop (or the default CurrentBPS = 0.25 s retrigger), Drum.Update re-fires the held pad every 1/BPS seconds while a touch ID remains down.
• Arrange. Pads are dragged by their selected touch ID (Drum.Select / DeSelect), drawn lime while selected; three presets rebuild fixed pad layouts (Game1.LoadStandardArrangement1/2/3); a config dialog edits type, both samples, zoom, layer depth, loop and can delete or create pads.
• Polyphony. Game1.PlaySound keeps at most 12 SoundEffectInstances; the oldest is stopped and disposed first. Volume comes from the options dialog (DrumsVolume).
• Recording. While RecordMode, every hit appends DrumRecordEvent { Time = now − RecordStartTime, Drum, Sound }. PlayButtonExecute copies RecordedPattern to PlaybackPattern and Game1.Update fires events whose timestamp has elapsed (removing each in turn); the pattern loops implicitly by re-recording/clearing.
• Metronome. BPM defaults to 120, range 40–340, slider step 3; MetronomeTimer = 60/BPM; audio (tick sample) and visual (pad flash) styles are independent checkboxes. Options store music/drums volume, pad animation, spotlights and colour.
• Persistence: none beyond the session (patterns and layout reset on exit).

4. Controls

Multi-touch and deeply gesture-driven. Tap a pad to strike; hold for loop retrigger; different zones of one pad trigger the second sample. In Arrange mode, drag a pad with one finger to reposition (Drum.Select records the selection offset) and use the zoom slider to scale the whole kit. Menu entries are taps; sliders drag horizontally; checkboxes toggle. The metronome and options dialogs are modal (input grabbed, first outside tap dismisses). There is no accelerometer input.

5. Content inventory (must be re-authored)

139 XNB files: 39 UI/texture XNBs (pad art KickBass/Tom/Snare/HiHat/Crash/ RedButton, floor, menu, dialogs, sliders, buttons, splash, fonts, light ray) and 100 per-sound XNBs under Sound/. The shipped audio set is kick 1–21, conga 1–4, hihat 1–14, crash 1–10, clap 1–3 and misc 1–48; the code additionally references tom 1–8, snare 1–30, ride 1–2 and misc up to 67, which are absent from this package (the app was authored against a larger library). These are third-party samples and must not be copied.

Re-authoring: synthesize a compact kit in MiniSynth — kick (swept sine), snare (noise + tone), closed/open hat (noise bursts), tom (pitched sine), crash/ride (noise + metallic partials), clap (multi-burst noise) and a few percussion/misc voices. Pad chrome becomes token rectangles/circles with zero radius; the six texture families collapse to labelled token surfaces.

6. Implementation plan

• Engine: new ui/apps/drums/DrumMachineEngine.kt — object DrumMachineEngine
  • immutable data class DrumMachineState(mode, bpm, pads, recorded, selectedPad); data class DrumPad(id, x, y, size, type, soundA, soundB, loopBps, layerDepth). Pure functions: hit(pad, u, v) zone split, record(elapsedMs, pad, zone), dueEvents(elapsedMs), setBpm.
• UI: replace DrumMachineApp() (PianoDrum.kt:118) with ui/apps/drums/DrumMachineApp.kt using DetailScaffold(title = "drum machine"), a Canvas stage for draggable pads, a text menu row (arrange/record/play/config/options/metronome), and the existing MiniSynth for audio. Everything from LocalDoradoColors / DoradoTokens; no rounded corners.
• Fidelity gaps vs current code: only 3 fixed rows × 16 steps (no free-form pads, no drag, no layers/loop, no record/playback, no metronome, no options), and no polyphony cap or per-pad sample choice.
• Persistence: pad layout + BPM + options as a JSON string in graph.appState.put("drums", …); recorded patterns do not need to survive exit (device didn't).
• Tests: app/src/test/java/com/heretek/dorado_hd/DrumMachineEngineTest.kt — zone split (left/right and radial), loop retrigger timing, 12-voice polyphony eviction, record → playback timestamp ordering and one-shot removal, BPM clamp 40–340.
• Edge cases: overlapping pads and z-order (layer depth), deleting the selected pad, loop with multiple fingers on one pad, BPM changes mid-record, and zero-length patterns.

7. Citation log

DrumMachine!Game1.LoadContent, DrumMachine!Game1.LoadStandardArrangement1, DrumMachine!Game1.PlaySound, DrumMachine!Game1.RecordButtonExecute, DrumMachine!Game1.PlayButtonExecute, DrumMachine!Game1.StopButtonExecute, DrumMachine!Game1.SetArrangeMode, DrumMachine!Game1.HandleInput, DrumMachine!Game1.Update, DrumMachine!Drum.Play, DrumMachine!Drum.PointOnDrum, DrumMachine!Drum.ChangeType, DrumMachine!Drum.Update, DrumMachine!Drum.Select, DrumMachine!Drum.DeSelect, DrumMachine!DrumRecordEvent, DrumMachine!ConfigDialog, DrumMachine!MetronomeDialog.TempoForwardExecute, DrumMachine!MetronomeDialog.BPMSliderExecute, DrumMachine!OptionsDialog.DrumsVolSliderExecute, DrumMachine!Menu.Show, DrumMachine!DiscoLight.AddLightCone, DrumMachine!Dialog.Show.