<!DOCTYPE html>
<meta charset="UTF-8">
<title>aspect-ratio interpolation</title>
<link rel="help" href="https://drafts.csswg.org/css-sizing-4/#aspect-ratio">
<meta name="assert" content="aspect-ratio supports animation">

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

<style>
.target {
  font-size: 16px;
  background-color: black;
  width: 10px;
  aspect-ratio: 0.5;
}
</style>

<body>
  <template id="target-template">
    <div class="container">
      <div class="target"></div>
    </div>
  </template>
</body>

<script>
test_interpolation({
  property: 'aspect-ratio',
  from: '0.5',
  to: '2',
}, [
  {at: -0.5, expect: '0.25 / 1'},
  {at: 0, expect: '0.5 / 1'},
  {at: 0.5, expect: '1 / 1'},
  {at: 1, expect: '2 / 1'},
  {at: 1.5, expect: '4 / 1'}
]);

test_interpolation({
  property: 'aspect-ratio',
  from: '1 / 2',
  to: '2 / 1',
}, [
  {at: -0.5, expect: '0.25 / 1'},
  {at: 0, expect: '0.5 / 1'},
  {at: 0.5, expect: '1 / 1'},
  {at: 1, expect: '2 / 1'},
  {at: 1.5, expect: '4 / 1'}
]);

// Test neutral keyframe
test_interpolation({
  property: 'aspect-ratio',
  from: '',
  to: '2 / 1',
}, [
  {at: -0.5, expect: '0.25 / 1'},
  {at: 0, expect: '0.5 / 1'},
  {at: 0.5, expect: '1 / 1'},
  {at: 1, expect: '2 / 1'},
  {at: 1.5, expect: '4 / 1'}
]);

test_interpolation({
  property: 'aspect-ratio',
  from: 'auto 1 / 2',
  to: 'auto 2 / 1',
}, [
  {at: -0.5, expect: 'auto 0.25 / 1'},
  {at: 0, expect: 'auto 0.5 / 1'},
  {at: 0.5, expect: 'auto 1 / 1'},
  {at: 1, expect: 'auto 2 / 1'},
  {at: 1.5, expect: 'auto 4 / 1'}
]);

test_no_interpolation({
  property: 'aspect-ratio',
  from: 'auto',
  to: '2 / 1',
});

test_no_interpolation({
  property: 'aspect-ratio',
  from: 'auto 1 / 1',
  to: '2 / 1',
});

// If either number in the ratio is 0 or infinite, it represents a degenerate
// ratio and will not be interpolated:
// https://drafts.csswg.org/css-values-4/#combine-ratio
test_no_interpolation({
  property: 'aspect-ratio',
  from: '1 / 0',
  to: '1 / 1',
});
test_no_interpolation({
  property: 'aspect-ratio',
  from: '1 / 1',
  to: '0 / 1',
});

// Addition of <ratio>s is not possible.
// https://drafts.csswg.org/css-values/#combine-ratio
//
// And if a value type does not define a specific procedure for addition or is
// defined as not additive, its addition operation is simply Vresult = Va.
// (The first value is Va, the second value is Vb, and the result is Vresult.)
// https://drafts.csswg.org/css-values-4/#not-additive,
//
// So in this test case:
// 1. The 1st keyframe: { aspectRatio: 0.5/1, composite: 'replace', offset: 0 }
// 2. The 2nd keyframe: { aspectRatio:   1/1, composite: 'add',     offset: 1 }
// and the underlying value is 2/1. Based on the spec, the composited from_value
// is 0.5/1 (because we just replace it), and the composited to_value is 2/1
// (because we use Va as the result value).
test_composition({
  property: 'aspect-ratio',
  underlying: '2 / 1',
  replaceFrom: '0.5 / 1',
  addTo: '1 / 1',
}, [
  {at: 0, expect: '0.5 / 1'},
  {at: 0.5, expect: '1 / 1'},
  {at: 1, expect: '2 / 1'}
]);

</script>
</body>
