Function createImageDataWS

apps/desktop/src/utils/socket.ts:259–1366

(
	url: string,
	onmessage: (data: FrameData) => void,
	onRequestFrame?: () => void,
	options: ImageDataWSOptions = {},
)

	| RequestFrameMessage;

export function createImageDataWS(
	url: string,
	onmessage: (data: FrameData) => void,
	onRequestFrame?: () => void,
	options: ImageDataWSOptions = {},
): [
	Omit<WebSocket, "onmessage">,
	() => boolean,
	() => boolean,
	CanvasControls,
] {
	const [isConnected, setIsConnected] = createSignal(false);
	const [isWorkerReady, setIsWorkerReady] = createSignal(false);
	const ws = createWS(url);

	// The frame worker (and its SharedArrayBuffer) only exists for the
	// OffscreenCanvas path; the direct-canvas consumers never need it, so it
	// is created lazily to avoid a worker + SAB reservation per window.
	let worker: Worker | null = null;
	let workerCanvasMode = false;
	let pendingFrame: ArrayBuffer | null = null;
	let isProcessing = false;
	let isProcessingSharedFrame = false;
	let nextFrame: ArrayBuffer | null = null;

	let producer: Producer | null = null;

	function ensureWorker(): Worker {
		if (worker) return worker;
		worker = new FrameWorker();
		worker.onmessage = handleWorkerMessage;
		if (SAB_SUPPORTED) {
			try {
				const init = createSharedFrameBuffer(FRAME_BUFFER_CONFIG);
				producer = createProducer(init);
				worker.postMessage({
					type: "init-shared-buffer",
					buffer: init.buffer,
				});
			} catch (e) {
				console.error(
					"[socket] SharedArrayBuffer allocation failed, falling back to non-SAB mode:",
					e instanceof Error ? e.message : e,
				);
				producer = null;
			}
		}
		return worker;
	}

	const [hasRenderedFrame, setHasRenderedFrame] = createSignal(false);
	let isCleanedUp = false;

	let directCanvas: HTMLCanvasElement | null = null;
	let directCtx: CanvasRenderingContext2D | null = null;
	let strideWorker: Worker | null = null;

	let cachedDirectImageData: ImageData | null = null;