css/css-color/animation/opacity-interpolation.html

<!DOCTYPE html>
<meta charset="UTF-8">
<title>opacity interpolation</title>
<link rel="help" href="https://drafts.csswg.org/css-color-3/#opacity">
<meta name="assert" content="opacity supports animation">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/css/support/interpolation-testcommon.js"></script>

<style>
.parent {
  opacity: 0.8;
}

.target {
  width: 100px;
  height: 100px;
  background-color: black;
  display: inline-block;
  opacity: 0.1;
}

.expected {
  background-color: green;
}
</style>

<body>
<script>
test_interpolation({
  property: 'opacity',
  from: neutralKeyframe,
  to: '0.2',
}, [
  {at: -0.3, expect: '0.07'},
  {at: 0, expect: '0.1'},
  {at: 0.3, expect: '0.13'},
  {at: 0.6, expect: '0.16'},
  {at: 1, expect: '0.2'},
  {at: 1.5, expect: '0.25'},
]);

test_interpolation({
  property: 'opacity',
  from: 'initial',
  to: '0.2',
}, [
  {at: -0.3, expect: '1'},
  {at: 0, expect: '1'},
  {at: 0.3, expect: '0.76'},
  {at: 0.6, expect: '0.52'},
  {at: 1, expect: '0.2'},
  {at: 1.5, expect: '0'},
]);

test_interpolation({
  property: 'opacity',
  from: 'inherit',
  to: '0.2',
}, [
  {at: -0.3, expect: '0.98'},
  {at: 0, expect: '0.8'},
  {at: 0.3, expect: '0.62'},
  {at: 0.6, expect: '0.44'},
  {at: 1, expect: '0.2'},
  {at: 1.5, expect: '0'},
]);

test_interpolation({
  property: 'opacity',
  from: 'unset',
  to: '0.2',
}, [
  {at: -0.3, expect: '1'},
  {at: 0, expect: '1'},
  {at: 0.3, expect: '0.76'},
  {at: 0.6, expect: '0.52'},
  {at: 1, expect: '0.2'},
  {at: 1.5, expect: '0'},
]);

test_interpolation({
  property: 'opacity',
  from: '0',
  to: '1'
}, [
  {at: -0.3, expect: '0'}, // CSS opacity is [0-1].
  {at: 0, expect: '0'},
  {at: 0.3, expect: '0.3'},
  {at: 0.6, expect: '0.6'},
  {at: 1, expect: '1'},
  {at: 1.5, expect: '1'}
]);
</script>
</body>