<!DOCTYPE html>
<!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. -->
<title>OffscreenCanvas test: 2d.filter.canvasFilterObject.componentTransfer.gamma.tentative</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/html/canvas/resources/canvas-tests.js"></script>

<h1>2d.filter.canvasFilterObject.componentTransfer.gamma.tentative</h1>
<p class="desc">Test pixels on CanvasFilter() componentTransfer with gamma type</p>


<script>
var t = async_test("Test pixels on CanvasFilter() componentTransfer with gamma type");
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');

  // From https://www.w3.org/TR/SVG11/filters.html#feComponentTransferElement
  function getColor(inputColor, amplitude, exponent, offset) {
      return [
          Math.max(0, Math.min(1, Math.pow(inputColor[0]/255, exponent[0]) * amplitude[0] + offset[0])) * 255,
          Math.max(0, Math.min(1, Math.pow(inputColor[1]/255, exponent[1]) * amplitude[1] + offset[1])) * 255,
          Math.max(0, Math.min(1, Math.pow(inputColor[2]/255, exponent[2]) * amplitude[2] + offset[2])) * 255,
      ];
  }

  const amplitudes = [2, 1.1, 0.5];
  const exponents = [5, 3, 1];
  const offsets = [0.25, 0, 0.5];
  ctx.filter = new CanvasFilter({filter: 'componentTransfer',
      funcR: {type: 'gamma', amplitude: amplitudes[0], exponent: exponents[0], offset: offsets[0]},
      funcG: {type: 'gamma', amplitude: amplitudes[1], exponent: exponents[1], offset: offsets[1]},
      funcB: {type: 'gamma', amplitude: amplitudes[2], exponent: exponents[2], offset: offsets[2]},
  });

  const inputColors = [
      [255, 255, 255],
      [0, 0, 0],
      [127, 0, 34],
      [252, 186, 3],
      [50, 68, 87],
  ];

  for (const color of inputColors) {
      let outputColor = getColor(color, amplitudes, exponents, offsets);
      ctx.fillStyle = `rgb(${color[0]}, ${color[1]}, ${color[2]})`;
      ctx.fillRect(0, 0, 10, 10);
      _assertPixelApprox(canvas, 5, 5, outputColor[0],outputColor[1],outputColor[2],255, 2);
  }
  t.done();

});
</script>
