Merge pull request #1 from CrispyBaguette/web-worker
Web worker and HTML tweaks
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CrispyBaguette
GitHub
commit
f8f71c56e5
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@ -1,19 +1,24 @@
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# wasm-palette-converter
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Go+Wasm image palette converter
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Build with:
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```bash
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GOOS=js GOARCH=wasm go build -o dist/main.wasm .
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```
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Access with:
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```
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cd dist
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npx http-server
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```
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A version is also available on IPFS:
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```
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/ipfs/QmQ4ptP2z6SonqyZfF5AiqgPa8RzHpPVyZWvZ8aVNxcoC9
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/ipfs/QmU6MmYFEvEYcNLdJZKJ7LfTuAPhPnpLwiUt4YcmANQESP
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```
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You can access it directly [here](https://ipfs.io/ipfs/QmQ4ptP2z6SonqyZfF5AiqgPa8RzHpPVyZWvZ8aVNxcoC9/).
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You can access it directly [here](https://ipfs.io/ipfs/QmU6MmYFEvEYcNLdJZKJ7LfTuAPhPnpLwiUt4YcmANQESP/).
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29
dist/index.html
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29
dist/index.html
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@ -1,8 +1,8 @@
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<html>
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<head>
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<meta charset="utf-8" />
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<script src="./wasm_exec.js"></script>
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<script async src="./main.js"></script>
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<script type="module" src="./wasm_exec.js"></script>
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<script type="module" src="./main.js"></script>
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<style>
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@media (prefers-color-scheme: dark) {
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body {
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@ -57,8 +57,19 @@
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algorithm.
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</p>
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<p>
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Performance isn't great, as Go+Wasm only runs on a single thread. The
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Wasm call also blocks the rendering (that would be fixable, though).
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Running in the browser with Wasm causes a bit of a performance penalty.
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Multithreading is not available (not that it matters much since
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Floyd-Steinberg is single-threaded), and sending data back and forth
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between JS and Wasm can take a little while.
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</p>
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<p>
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I've re-used code from
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<a
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href="https://www.sitepen.com/blog/using-webassembly-with-web-workers"
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>this article</a
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>
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to make the Wasm code run in a web worker, with some adaptations for Go
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oddities.
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</p>
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<p>
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If you're into that sort of thing, source code is available on
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@ -68,11 +79,13 @@
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</p>
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<form>
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<input type="file" id="source-image" accept="image/png, image/jpeg" />
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<button id="go-btn" type="button">Go</button>
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<button id="go-btn" type="button" disabled>Go</button>
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</form>
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<div class="container">
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<img id="output" />
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</div>
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<a id="output-wrapper" download="output.png">
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<div class="container">
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<img id="output" />
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</div>
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</a>
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</article>
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</body>
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</html>
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122
dist/main.js
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122
dist/main.js
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@ -1,38 +1,94 @@
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(async () => {
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// Load element references
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const fileInput = document.getElementById("source-image");
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const btn = document.getElementById("go-btn");
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const fileInput = document.getElementById("source-image");
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const btn = document.getElementById("go-btn");
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const output = document.getElementById("output");
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const outputWrapper = document.getElementById("output-wrapper");
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// Setup Wasm stuff
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const go = new Go();
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vm = await WebAssembly.instantiateStreaming(
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fetch("./main.wasm"),
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go.importObject
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);
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go.run(vm.instance);
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function wasmWorker(modulePath) {
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// Create an object to later interact with
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const proxy = {};
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// Setup event listener
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btn.addEventListener("click", async () => {
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// Clear image
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outputElement = document.getElementById("output");
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outputElement.src = "";
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// Keep track of the messages being sent
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// so we can resolve them correctly
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let id = 0;
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let idPromises = {};
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// Check if a file was selected
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if (fileInput.files.length === 0) {
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alert("No file selected");
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return;
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}
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reader = new FileReader();
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reader.readAsArrayBuffer(fileInput.files[0]);
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reader.Read;
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reader.onloadend = async (evt) => {
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if (evt.target.readyState === FileReader.DONE) {
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const array = new Uint8Array(evt.target.result);
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// Wasm magic happens here
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ditheredImageData = await DitherNord(array);
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document.getElementById("output").src =
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"data:image/png;base64," + ditheredImageData;
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return new Promise((resolve, reject) => {
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const worker = new Worker("worker.js");
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worker.postMessage({ eventType: "INITIALISE", eventData: modulePath });
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worker.addEventListener("message", function (event) {
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const { eventType, eventData, eventId } = event.data;
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if (eventType === "INITIALISED") {
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const methods = event.data.eventData;
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methods.forEach((method) => {
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proxy[method] = function () {
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return new Promise((resolve, reject) => {
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worker.postMessage({
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eventType: "CALL",
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eventData: {
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method: method,
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arguments: Array.from(arguments), // arguments is not an array
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},
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eventId: id,
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});
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idPromises[id] = { resolve, reject };
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id++;
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});
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};
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});
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resolve(proxy);
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return;
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} else if (eventType === "RESULT") {
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if (eventId !== undefined && idPromises[eventId]) {
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idPromises[eventId].resolve(eventData);
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delete idPromises[eventId];
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}
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} else if (eventType === "ERROR") {
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if (eventId !== undefined && idPromises[eventId]) {
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idPromises[eventId].reject(event.data.eventData);
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delete idPromises[eventId];
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}
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}
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};
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});
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worker.addEventListener("error", function (error) {
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reject(error);
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});
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});
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})();
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}
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let workerResolve;
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const wasmReady = new Promise((resolve) => {
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workerResolve = resolve;
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});
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let workerProxy;
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wasmWorker("./main.wasm").then((w) => {
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workerProxy = w;
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workerResolve();
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btn.removeAttribute("disabled");
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});
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btn.addEventListener("click", async () => {
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// Clear image
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output.src = "";
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// Check if a file was selected
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if (fileInput.files.length === 0) {
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alert("No file selected");
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return;
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}
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const reader = new FileReader();
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reader.readAsArrayBuffer(fileInput.files[0]);
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reader.onloadend = async (evt) => {
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if (evt.target.readyState === FileReader.DONE) {
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const imageData = new Uint8Array(evt.target.result);
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const ditheredImage = await workerProxy.DitherNord(imageData);
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const outputValue = `data:image/png;base64,${ditheredImage}`;
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output.src = outputValue;
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outputWrapper.href = outputValue;
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}
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};
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});
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61
dist/worker.js
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61
dist/worker.js
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@ -0,0 +1,61 @@
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importScripts("./wasm_exec.js");
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if (!WebAssembly.instantiateStreaming) {
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WebAssembly.instantiateStreaming = async (resp, importObject) => {
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const source = await (await resp).arrayBuffer();
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return await WebAssembly.instantiate(source, importObject);
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};
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}
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// Create promise to handle Worker calls whilst
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// module is still initialising
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let wasmResolve;
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const wasmReady = new Promise((resolve) => {
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wasmResolve = resolve;
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});
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const go = new self.Go();
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addEventListener(
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"message",
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async (e) => {
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const { eventType, eventData, eventId } = e.data;
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if (eventType === "INITIALISE") {
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const instantiatedSource = await WebAssembly.instantiateStreaming(
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fetch(eventData),
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go.importObject
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);
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go.run(instantiatedSource.instance);
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// Go does nor exposes the exports in the instantiated module :(((
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const methods = ["DitherNord"];
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wasmResolve(methods);
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postMessage({
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eventType: "INITIALISED",
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eventData: methods,
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});
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} else if (eventType === "CALL") {
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await wasmReady;
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try {
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const method = self[eventData.method];
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const result = await method.apply(null, eventData.arguments);
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self.postMessage({
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eventType: "RESULT",
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eventData: result,
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eventId: eventId,
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});
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} catch (e) {
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console.error(e);
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self.postMessage({
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eventType: "ERROR",
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eventData:
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"An error occured executing WASM instance function: " +
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error.toString(),
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eventId: eventId,
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});
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}
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}
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},
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false
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);
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