javierandClaude Fable 5
6485997edc
System, Display, Graphics, Sprite, Sound, File, JSON, Lua, Scoreboards, Network, Rect, SystemEvent, and AccessReply now live at module scope instead of being nested in the Playdate enum; consumers write System.log(...) instead of Playdate.System.log(...), and can qualify with the module name (PlayDate.System) on collision. The Playdate enum remains only as the raw C API bootstrap (initialize(with:), api, apiPointer), and Playdate.Error is renamed PlaydateError so no top-level type shadows Swift.Error. Breaking change for any existing consumers. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
374 lines
13 KiB
Markdown
374 lines
13 KiB
Markdown
# PlayDate
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[](https://github.com/<you>/play-date/actions/workflows/ci.yml)
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Swift bindings to the [Playdate](https://play.date) C API.
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The Playdate C API is delivered as a `PlaydateAPI*` struct of function
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pointers that the firmware hands to your game at launch. This package wraps
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that surface in idiomatic Swift: namespaced APIs, wrapper types with
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ownership semantics, closures instead of function-pointer/userdata pairs,
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`OptionSet`s and `enum`s instead of raw constants, and typed `throws` for
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fallible calls.
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All ten C subsystems are covered:
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| Namespace | Wraps | Highlights |
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|---|---|---|
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| `System` | `playdate->system` | input, time, menu items, logging |
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| `Display` | `playdate->display` | refresh rate, scale, mosaic, flip |
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| `Graphics` | `playdate->graphics` | drawing, `Bitmap`, `Font`, `TileMap`, video |
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| `Sprite` | `playdate->sprite` | display list, collisions, custom draw |
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| `Sound` | `playdate->sound` | players, synths, sequences, effects |
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| `File` | `playdate->file` | `Handle`, directory operations |
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| `JSON` | `playdate->json` | `Value` tree decode/encode |
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| `Lua` | `playdate->lua` | C functions, classes, stack access |
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| `Scoreboards` | `playdate->scoreboards` | online leaderboards |
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| `Network` | `playdate->network` | wifi, `HTTPConnection`, `TCPConnection` |
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## Requirements
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- The [Playdate SDK](https://play.date/dev/) (3.1.1 or later). The SDK is
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not vendored into this repository.
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- Swift 6.4 tools or later.
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### One-time SDK setup
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The `CPlaydate` target resolves `pd_api.h` through a `playdate` pkg-config
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module, so the package works as a normal SwiftPM dependency without unsafe
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build flags. Generate the pkg-config file once per machine:
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```sh
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Scripts/install-pkgconfig.sh
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```
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The script locates the SDK via `PLAYDATE_SDK_PATH` (default
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`~/Developer/PlaydateSDK`) and writes `playdate.pc` into a directory SwiftPM
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searches by default (`/usr/local/lib/pkgconfig`). Pass a custom destination
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as an argument if you prefer another location on your `PKG_CONFIG_PATH`.
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If Xcode had the package open before you ran the script, make it re-read the
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manifest (File ▸ Packages ▸ Reset Package Caches) — Xcode caches package
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resolution and won't notice the new `.pc` file on its own.
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## Adding the dependency
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```swift
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// Package.swift of your game
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dependencies: [
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.package(url: "https://github.com/<you>/play-date.git", from: "0.1.0"),
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// …or, while developing locally:
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// .package(path: "../play-date"),
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],
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targets: [
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.target(
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name: "MyGame",
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dependencies: [.product(name: "PlayDate", package: "play-date")]
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),
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]
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```
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## Getting started
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A Playdate game has a single C entry point, `eventHandler`. Export it with
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`@_cdecl`, initialize the binding on the first event, and install an update
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callback:
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```swift
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import CPlaydate
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import PlayDate
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@_cdecl("eventHandler")
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func eventHandler(pointer: UnsafeMutableRawPointer,
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event: PDSystemEvent,
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argument: UInt32) -> Int32 {
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switch SystemEvent(event: event, argument: argument) {
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case .initialize:
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Playdate.initialize(with: pointer) // must happen before anything else
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Game.shared.start()
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case .pause:
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Game.shared.pause()
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default:
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break
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}
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return 0
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}
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final class Game {
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nonisolated(unsafe) static let shared = Game()
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var player = Sprite()
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func start() {
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Display.setRefreshRate(50)
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System.setUpdateCallback {
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self.update()
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return true // true = redraw the display this frame
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}
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}
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func update() {
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let (_, pushed, _) = System.buttonState
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if pushed.contains(.a) {
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System.log("A pressed at \(System.currentTimeMilliseconds)ms")
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}
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Sprite.updateAndDrawAll()
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System.drawFPS()
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}
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}
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```
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`Playdate.initialize(with:)` stores the API pointer once; every wrapper in
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the module uses it from then on. Calling any wrapper before `initialize` is
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a programmer error and will crash.
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## Tour of the API
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### System: input, time, menu
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```swift
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// Buttons are an OptionSet: current (held), pushed and released this frame.
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let (current, pushed, released) = System.buttonState
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if current.contains([.b, .down]) { /* charge shot */ }
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// Crank.
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if !System.isCrankDocked {
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aim(degrees: System.crankAngle)
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spin(by: System.crankChange)
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}
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// Accelerometer is a peripheral you enable first.
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System.setPeripheralsEnabled(.accelerometer)
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let (x, y, z) = System.accelerometer
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// System menu items take closures; the binding keeps them alive until removed.
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System.addCheckmarkMenuItem(title: "music", isChecked: true) { item in
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Audio.musicEnabled = item.isChecked
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}
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System.addOptionsMenuItem(title: "mode", options: ["easy", "hard"]) { item in
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Game.shared.difficulty = item.value
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}
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// Logging goes to the simulator console or device serial.
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System.log("spawned \(count) enemies")
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System.error("unrecoverable") // stops execution
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```
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### Graphics: drawing, bitmaps, fonts
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Fallible loads (`Bitmap(path:)`, `Font(path:)`, …) throw `PlaydateError`,
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which carries the message produced by the OS:
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```swift
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let font = try Graphics.Font(path: "fonts/Asheville-Sans-14-Bold.pft")
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Graphics.setFont(font)
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Graphics.clear(color: .white)
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Graphics.fillRect(x: 0, y: 0, width: 400, height: 32, color: .black)
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Graphics.drawText("Hëllo, Playdate", x: 8, y: 8)
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// Colors are solid or 8×8 patterns.
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let checker = Graphics.Pattern(rows: (0xAA, 0x55, 0xAA, 0x55,
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0xAA, 0x55, 0xAA, 0x55))
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Graphics.fillEllipse(x: 100, y: 100, width: 64, height: 64,
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color: .pattern(checker))
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// Bitmaps draw themselves; draw into one by pushing it as the context.
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let logo = try Graphics.Bitmap(path: "images/logo")
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logo.draw(x: 168, y: 88)
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let canvas = Graphics.Bitmap(width: 64, height: 64)
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Graphics.pushContext(canvas)
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Graphics.drawLine(x1: 0, y1: 0, x2: 63, y2: 63, width: 2, color: .black)
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Graphics.popContext()
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```
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### Sprites and collisions
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```swift
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let ball = Sprite()
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ball.setImage(try Graphics.Bitmap(path: "images/ball"))
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ball.moveTo(x: 200, y: 120)
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ball.collideRect = Rect(x: 0, y: 0, width: 16, height: 16)
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ball.setCollisionResponseFunction { _, _ in .bounce }
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ball.add() // adds to the display list; the binding keeps it alive while added
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// In the update callback:
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let (actual, collisions) = ball.moveWithCollisions(goalX: goalX, goalY: goalY)
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for collision in collisions where collision.other.tag == Tags.brick {
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collision.other.remove()
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}
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```
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Sprite callbacks (`setUpdateFunction`, `setDrawFunction`,
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`setCollisionResponseFunction`) receive the Swift wrapper back. The C-level
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sprite userdata slot is reserved by the binding for that recovery — use the
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`userdata` property on `Sprite` for your own per-sprite storage instead.
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### Sound
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```swift
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// Stream music from disk.
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let music = try Sound.FilePlayer(path: "audio/theme")
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music.play(repeat: 0) // 0 = loop forever
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// Play short effects from memory.
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let blip = try Sound.SamplePlayer(path: "audio/blip")
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blip.play()
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// Synthesis.
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let synth = Sound.Synth(waveform: .square)
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synth.setAttackTime(0.01)
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synth.setReleaseTime(0.2)
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synth.playMIDINote(Sound.noteC4, velocity: 0.8, length: 0.5)
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// Channels mix sources and effects.
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let channel = Sound.Channel()
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channel.add()
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channel.addSource(synth)
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let filter = Sound.TwoPoleFilter(kind: .lowPass)
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filter.setFrequency(800)
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channel.addEffect(filter)
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// Anything that takes a modulator accepts any SignalValue (LFO, Envelope, …).
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let wobble = Sound.LFO(shape: .sine)
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wobble.setRate(2)
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synth.frequencyModulator = wobble
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```
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### Files and JSON
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```swift
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// Paths resolve against the game's Data directory and pdx per the open mode.
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let save = try File.Handle(path: "save.json", mode: .write)
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try save.write(JSON.encode(.table([
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"level": .int(3),
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"name": .string("Röck"),
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])))
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try save.close()
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let loaded = try JSON.decodeFile(at: "save.json")
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if case .table(let entries) = loaded, case .int(let level)? = entries["level"] {
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Game.shared.level = level
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}
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try File.listFiles(at: "replays") { name in
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System.log("found \(name)")
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}
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```
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### Network
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Network access requires user permission per server:
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```swift
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let reply = Network.HTTPConnection.requestAccess(
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server: "example.com", purpose: "Fetching daily puzzles") { allowed in
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guard allowed else { return }
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Puzzles.fetch()
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}
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func fetch() {
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guard let connection = Network.HTTPConnection(server: "example.com") else { return }
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connection.setRequestCompleteCallback { connection in
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let body = try? connection.read(length: connection.bytesAvailable)
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// … keep `connection` referenced somewhere until this fires …
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}
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try? connection.get(path: "/daily.json")
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}
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```
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### Lua interop
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Lua callbacks are C function pointers with no context, so they must be
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`@convention(c)` functions rather than capturing closures:
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```swift
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let double: Lua.CFunction = { _ in
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Lua.push(Lua.intArgument(at: 1) * 2)
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return 1 // number of return values pushed
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}
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try Lua.addFunction(double, name: "mylib.double")
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```
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## Conventions
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- **Namespaces.** The subsystem namespaces (`System`, `Graphics`, `Sound`,
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…) live at the top level of the module; only the raw C API bootstrap
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stays under `Playdate` (`Playdate.initialize(with:)`, `Playdate.api`).
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On a name collision with another module, qualify with the module name:
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`PlayDate.System`.
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- **Errors.** Fallible operations use typed throws — `throws(PlaydateError)`
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generally, `throws(Network.NetError)` for network I/O — so `catch`
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gives you a concrete type, and no `any Error` existentials are needed.
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- **Ownership.** A wrapper that *creates* a C object frees it on `deinit`;
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keep the wrapper referenced for as long as you use it. Wrappers vending
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OS-owned objects (a `Bitmap` from a `BitmapTable`, a track from a
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`Sequence`, …) don't free them — keep the owner alive instead, as
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documented on each API. Resources a C object keeps referencing (a sprite's
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image, a synth's sample, modulators, menu-item option titles) are retained
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by the wrapper automatically.
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- **Callbacks.** Where the C API provides a userdata slot, closures are
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supported everywhere and delivered back with the right wrapper. A few C
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callbacks have no userdata (serial messages, headphone changes, scoreboard
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completions, `getServerTime`); those track one Swift closure at a time, as
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noted in their documentation.
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- **Threading.** The Playdate runtime is single-threaded (audio callbacks
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excepted); statics in the binding are `nonisolated(unsafe)` on that basis.
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Don't call the API from other threads.
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## Building for the simulator and device
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This package builds as a plain Swift library, which is how you develop and
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unit-test game logic on the host (`swift test` works out of the box).
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Shipping a `.pdx` needs the Playdate toolchain on top:
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- **Simulator** builds compile your game as a host dylib placed in the pdx.
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- **Device** builds require Embedded Swift for ARM Cortex-M7
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(`-enable-experimental-feature Embedded`, triple `armv7em-none-none-eabi`).
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The wrappers are written within the Embedded Swift subset for exactly this
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reason: no Foundation, no reflection, no untyped throws. That claim is
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enforced, not aspirational: `Scripts/build-embedded.sh` cross-compiles the
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whole module for `armv7em-none-none-eabi` with Embedded Swift enabled, and
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CI runs it on every push. Running it locally needs a swift.org development
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snapshot toolchain (Xcode's toolchain doesn't ship the bare-metal embedded
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stdlib) and the Arm GNU toolchain headers:
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```sh
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SWIFT_BIN=~/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-<date>.xctoolchain/usr/bin/swift \
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Scripts/build-embedded.sh
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```
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See Apple's
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[swift-playdate-examples](https://github.com/apple/swift-playdate-examples)
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for a working Makefile/toolchain setup that this library slots into.
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## Layout
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```
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Scripts/
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install-pkgconfig.sh One-time setup: points the "playdate" pkg-config
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module at your SDK installation
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build-embedded.sh Compile-only device check: Embedded Swift for
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armv7em-none-none-eabi (run by CI)
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consumer-test.sh Builds a scratch package depending on play-date
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to prove settings propagate to consumers (CI)
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Sources/
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CPlaydate/ System library target: module map + umbrella header
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importing pd_api.h from the SDK, plus inline shims for
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the variadic log/error functions
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PlayDate/ The Swift bindings, one file per subsystem
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(Sound and Graphics are split across several files)
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Tests/
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PlayDate/ Host-runnable tests for the pure value types
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```
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## License
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MIT — see [LICENSE](LICENSE). The Playdate SDK itself is licensed separately
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by Panic, Inc. and is not distributed with this package.
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