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| 1 | +import JavaScriptEventLoop |
| 2 | +import JavaScriptKit |
| 3 | + |
| 4 | +JavaScriptEventLoop.installGlobalExecutor() |
| 5 | +WebWorkerTaskExecutor.installGlobalExecutor() |
| 6 | + |
| 7 | +protocol CanvasRenderer { |
| 8 | + func render(canvas: JSObject, size: Int) async throws |
| 9 | +} |
| 10 | + |
| 11 | +struct BackgroundRenderer: CanvasRenderer { |
| 12 | + func render(canvas: JSObject, size: Int) async throws { |
| 13 | + let executor = try await WebWorkerTaskExecutor(numberOfThreads: 1) |
| 14 | + let transfer = JSSending.transfer(canvas) |
| 15 | + let renderingTask = Task(executorPreference: executor) { |
| 16 | + let canvas = try await transfer.receive() |
| 17 | + try await renderAnimation(canvas: canvas, size: size) |
| 18 | + } |
| 19 | + await withTaskCancellationHandler { |
| 20 | + try? await renderingTask.value |
| 21 | + } onCancel: { |
| 22 | + renderingTask.cancel() |
| 23 | + } |
| 24 | + executor.terminate() |
| 25 | + } |
| 26 | +} |
| 27 | + |
| 28 | +struct MainThreadRenderer: CanvasRenderer { |
| 29 | + func render(canvas: JSObject, size: Int) async throws { |
| 30 | + try await renderAnimation(canvas: canvas, size: size) |
| 31 | + } |
| 32 | +} |
| 33 | + |
| 34 | +// FPS Counter for CSS animation |
| 35 | +func startFPSMonitor() { |
| 36 | + let fpsCounterElement = JSObject.global.document.getElementById("fps-counter").object! |
| 37 | + |
| 38 | + var lastTime = JSObject.global.performance.now().number! |
| 39 | + var frames = 0 |
| 40 | + |
| 41 | + // Create a frame counter function |
| 42 | + func countFrame() { |
| 43 | + frames += 1 |
| 44 | + let currentTime = JSObject.global.performance.now().number! |
| 45 | + let elapsed = currentTime - lastTime |
| 46 | + |
| 47 | + if elapsed >= 1000 { |
| 48 | + let fps = Int(Double(frames) * 1000 / elapsed) |
| 49 | + fpsCounterElement.textContent = .string("FPS: \(fps)") |
| 50 | + frames = 0 |
| 51 | + lastTime = currentTime |
| 52 | + } |
| 53 | + |
| 54 | + // Request next frame |
| 55 | + _ = JSObject.global.requestAnimationFrame!( |
| 56 | + JSClosure { _ in |
| 57 | + countFrame() |
| 58 | + return .undefined |
| 59 | + }) |
| 60 | + } |
| 61 | + |
| 62 | + // Start counting |
| 63 | + countFrame() |
| 64 | +} |
| 65 | + |
| 66 | +@MainActor |
| 67 | +func onClick(renderer: CanvasRenderer) async throws { |
| 68 | + let document = JSObject.global.document |
| 69 | + |
| 70 | + let canvasContainerElement = document.getElementById("canvas-container").object! |
| 71 | + |
| 72 | + // Remove all child elements from the canvas container |
| 73 | + for i in 0..<Int(canvasContainerElement.children.length.number!) { |
| 74 | + let child = canvasContainerElement.children[i] |
| 75 | + _ = canvasContainerElement.removeChild!(child) |
| 76 | + } |
| 77 | + |
| 78 | + let canvasElement = document.createElement("canvas").object! |
| 79 | + _ = canvasContainerElement.appendChild!(canvasElement) |
| 80 | + |
| 81 | + let size = 800 |
| 82 | + canvasElement.width = .number(Double(size)) |
| 83 | + canvasElement.height = .number(Double(size)) |
| 84 | + |
| 85 | + let offscreenCanvas = canvasElement.transferControlToOffscreen!().object! |
| 86 | + try await renderer.render(canvas: offscreenCanvas, size: size) |
| 87 | +} |
| 88 | + |
| 89 | +func main() async throws { |
| 90 | + let renderButtonElement = JSObject.global.document.getElementById("render-button").object! |
| 91 | + let cancelButtonElement = JSObject.global.document.getElementById("cancel-button").object! |
| 92 | + let rendererSelectElement = JSObject.global.document.getElementById("renderer-select").object! |
| 93 | + |
| 94 | + var renderingTask: Task<Void, Error>? = nil |
| 95 | + |
| 96 | + // Start the FPS monitor for CSS animations |
| 97 | + startFPSMonitor() |
| 98 | + |
| 99 | + _ = renderButtonElement.addEventListener!( |
| 100 | + "click", |
| 101 | + JSClosure { _ in |
| 102 | + renderingTask?.cancel() |
| 103 | + renderingTask = Task { |
| 104 | + let selectedValue = rendererSelectElement.value.string! |
| 105 | + let renderer: CanvasRenderer = |
| 106 | + selectedValue == "main" ? MainThreadRenderer() : BackgroundRenderer() |
| 107 | + try await onClick(renderer: renderer) |
| 108 | + } |
| 109 | + return JSValue.undefined |
| 110 | + }) |
| 111 | + |
| 112 | + _ = cancelButtonElement.addEventListener!( |
| 113 | + "click", |
| 114 | + JSClosure { _ in |
| 115 | + renderingTask?.cancel() |
| 116 | + return JSValue.undefined |
| 117 | + }) |
| 118 | +} |
| 119 | + |
| 120 | +Task { |
| 121 | + try await main() |
| 122 | +} |
| 123 | + |
| 124 | +#if canImport(wasi_pthread) |
| 125 | + import wasi_pthread |
| 126 | + import WASILibc |
| 127 | + |
| 128 | + /// Trick to avoid blocking the main thread. pthread_mutex_lock function is used by |
| 129 | + /// the Swift concurrency runtime. |
| 130 | + @_cdecl("pthread_mutex_lock") |
| 131 | + func pthread_mutex_lock(_ mutex: UnsafeMutablePointer<pthread_mutex_t>) -> Int32 { |
| 132 | + // DO NOT BLOCK MAIN THREAD |
| 133 | + var ret: Int32 |
| 134 | + repeat { |
| 135 | + ret = pthread_mutex_trylock(mutex) |
| 136 | + } while ret == EBUSY |
| 137 | + return ret |
| 138 | + } |
| 139 | +#endif |
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