2d.color.type.u8srgb.to.u8p3.to.u8srgb.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /html/canvas/offscreen/color-type/2d.color.type.u8srgb.to.u8p3.to.u8srgb.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">

<title>OffscreenCanvas test: 2d.color.type.u8srgb.to.u8p3.to.u8srgb</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="/html/canvas/resources/canvas-tests.js"></script>

<h1>2d.color.type.u8srgb.to.u8p3.to.u8srgb</h1>

<p class="desc">test display-p3 unorm8 canvas not storing 8-bit srgb data accurately</p>

<script>

var t = async_test("test display-p3 unorm8 canvas not storing 8-bit srgb data accurately");

var t_pass = t.done.bind(t);

var t_fail = t.step_func(function(reason) {

    throw reason;

});

t.step(function() {

  var canvas = new OffscreenCanvas(100, 50);

  var ctx = canvas.getContext('2d', {colorType: "unorm8", colorSpace: "display-p3"});

  // Consider the color in sRGB:

  //   (5,250,128)/255

  // In Display P3 this is:

  //   (0.4504003868394956, 0.9659537930632748, 0.5523945982276097)

  // Quantized to 8-bit, this is:

  //   (115, 246, 141)/255

  // Converted back to sRGB this is:

  //   (8.909609662725, 249.672568247041, 128.228541784731)/255

  // Quantized to 8-bit, this is:

  //   (9, 250, 128)

  var input = new ImageData(new Uint8ClampedArray([5, 250, 128, 255]),

                            1, 1, {colorSpace: "srgb"});

  ctx.putImageData(input, 0, 0);

  var readback = ctx.getImageData(0, 0, 1, 1, {colorSpace:"srgb"});

  const kEpsilon = 2;

  assert_approx_equals(readback.data[0], 9, kEpsilon);

  assert_approx_equals(readback.data[1], 250, kEpsilon);

  assert_approx_equals(readback.data[2], 128, kEpsilon);

  t.done();

});

</script>