2d.composite.globalAlpha.range.html

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This WPT test may be referenced by the following Test IDs:
- /html/canvas/offscreen/compositing/2d.composite.globalAlpha.range.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

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

<title>OffscreenCanvas test: 2d.composite.globalAlpha.range</title>

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

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

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

<h1>2d.composite.globalAlpha.range</h1>

<p class="desc"></p>

<script>

var t = async_test("");

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');

  ctx.globalAlpha = 0.5;

  // This may not set it to exactly 0.5 if it is rounded/quantised, so

  // remember for future comparisons.

  var a = ctx.globalAlpha;

  _assertSame(ctx.globalAlpha, a, "ctx.globalAlpha", "a");

  ctx.globalAlpha = 1.1;

  _assertSame(ctx.globalAlpha, a, "ctx.globalAlpha", "a");

  ctx.globalAlpha = -0.1;

  _assertSame(ctx.globalAlpha, a, "ctx.globalAlpha", "a");

  ctx.globalAlpha = 0;

  _assertSame(ctx.globalAlpha, 0, "ctx.globalAlpha", "0");

  ctx.globalAlpha = 1;

  _assertSame(ctx.globalAlpha, 1, "ctx.globalAlpha", "1");

  t.done();

});

</script>