1871755-1.html - mozsearch

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<!DOCTYPE HTML>

<html class="reftest-wait">

<head>

<title>Missing-font notifications from OffscreenCanvas2d</title>

</head>

<body>

</body>

<script>

// Workaround for bug 1962172: this will cause the CJK fallback order

// to be loaded on the main thread, before the worker tries to use it.

// (Can be removed when bug 1962172 is resolved.)

let canvas = new OffscreenCanvas(100, 100);

let ctx = canvas.getContext("2d");

ctx.measureText("\u4567\u9876");

// Try measuring a selection of characters from across the

// Unicode space; almost certainly this will hit some codepoints

// for which font support is lacking.

const blob = new Blob([`

  self.onmessage = (evt) => {

    let ctx = evt.data.canvas.getContext("2d");

    // Sampling planes 0 and 1 is enough; plane 2 just adds more CJK, not new scripts.

    for (plane = 0; plane < 2; ++plane) {

      let txt = "Plane " + plane + " text: ";

      for (block = 0; block < 256; ++block) {

        for (ch = 0; ch < 256; ch += 64) {

          txt += String.fromCodePoint(plane * 0x10000 + block * 0x100 + ch);

      ctx.measureText(txt);

      postMessage(txt);

    postMessage("Done");

`], {

  type: "application/typescript",

});

const url = URL.createObjectURL(blob);

const worker = new Worker(url);

worker.onmessage = (msg) => {

  console.log(msg.data);

  if (msg.data == "Done") {

    document.documentElement.classList.remove("reftest-wait")

};

let offscreen = new OffscreenCanvas(100, 100);

worker.postMessage({ canvas: offscreen }, [offscreen]);

</script>

</html>