24 lines
650 B
JavaScript
24 lines
650 B
JavaScript
onmessage = function (e) {
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const message = e.data;
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if (message === "IsETPAllowListed") {
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sendMessage(!isOffscreenAPlaceHolder());
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}
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};
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function isOffscreenAPlaceHolder() {
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const canvas = new OffscreenCanvas(4, 4);
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const context = canvas.getContext("2d");
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// An empty canvas would return 0,0,0,0 for the pixel data.
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return !context.getImageData(0, 0, 4, 4).data.every(el => el === 0);
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}
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function sendMessage(message) {
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self.clients.matchAll({ includeUncontrolled: true }).then(function (res) {
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if (!res.length) {
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dump("Error: no clients are available.\n");
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return;
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}
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res[0].postMessage(message);
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});
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}
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