2d.layer.non-invertible-matrix.w.html

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This WPT test may be referenced by the following Test IDs:
- /html/canvas/offscreen/layers/2d.layer.non-invertible-matrix.w.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. -->

<meta charset="UTF-8">

<html class="reftest-wait">

<link rel="match" href="2d.layer.non-invertible-matrix-expected.html">

<title>Canvas test: 2d.layer.non-invertible-matrix</title>

<h1>2d.layer.non-invertible-matrix</h1>

<p class="desc">Test drawing layers when the transform is not invertible.</p>

<canvas id="canvas" width="200" height="200">

  <p class="fallback">FAIL (fallback content)</p>

</canvas>

<script id='myWorker' type='text/worker'>

  self.onmessage = function(e) {

    const canvas = new OffscreenCanvas(200, 200);

    const ctx = canvas.getContext('2d');

    ctx.fillStyle = 'blue';

    ctx.fillRect(30, 30, 50, 50);

    // Anything below will be non-rasterizable.

    ctx.scale(1, 0);

    // Open the layer with a non-invertible matrix. The whole layer will be

    // non-rasterizable.

    ctx.beginLayer();

    // Because the transform is global, the matrix is still non-invertible.

    ctx.fillStyle = 'rgba(225, 0, 0, 1)';

    ctx.fillRect(40, 70, 50, 50);

    // Set a valid matrix in the middle of the layer. This makes the global

    // matrix invertible again, but because because the layer was opened with a

    // non-invertible matrix, the whole layer remains non-rasterizable.

    ctx.setTransform(1, 0, 0, 1, 0, 0);

    ctx.fillStyle = 'green';

    ctx.fillRect(70, 40, 50, 50);

    ctx.endLayer();

    const bitmap = canvas.transferToImageBitmap();

    self.postMessage(bitmap, bitmap);

};

</script>

<script>

  const blob = new Blob([document.getElementById('myWorker').textContent]);

  const worker = new Worker(URL.createObjectURL(blob));

  worker.addEventListener('message', msg => {

    const outputCtx = document.getElementById("canvas").getContext('2d');

    outputCtx.drawImage(msg.data, 0, 0);

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

});

  worker.postMessage(null);

</script>

</html>