Integer interpolation should be rounded towards positive infinity.

Currently, interpolation of <integer> is rounding away from 0. The interpolation's result should be rounded according to the spec, https://drafts.csswg.org/css-values-4/#combine-integers, which is "the result is converted to an <integer> by rounding to the nearest integer, with values halfway between adjacent integers rounded towards positive infinity." Bug: 1257732 Change-Id: I0dc9db806b88e66bf326b848c4e4ac90ef868ed4 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3225842 Reviewed-by: Robert Flack <flackr@chromium.org> Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org> Commit-Queue: Joonghun Park <pjh0718@gmail.com> Cr-Commit-Position: refs/heads/main@{#933277}
web-platform-tests · Oct 20, 2021 · ac544dd · ac544dd
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diff --git a/css/css-values/integer_interpolation_round_half_towards_positive_infinity_order.html b/css/css-values/integer_interpolation_round_half_towards_positive_infinity_order.html
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+<!doctype html>
+<title>Testing if integer interpolation is rounded towards positive infinity</title>
+<link rel="author" title="Joonghun Park" href="pjh0718@gmail.com">
+<link rel="help" href="https://drafts.csswg.org/css-values-4/#combine-integers">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+
+#flex-container {
+    display: flex;
+    animation: anim-order 4s steps(4) forwards 1;
+    animation-delay: -1s;
+    animation-play-state: paused;
+}
+
+@keyframes anim-order {
+  from {
+    order: -2;
+  }
+
+  to {
+    order: 0;
+  }
+}
+
+</style>
+<div id="flex-container"></div>
+<script>
+var test_description = "Integer interpolation should be rounded towards positive infinity";
+test(
+    t => {
+        const container = document.getElementById("flex-container");
+        const order_value = Number.parseFloat(getComputedStyle(container).getPropertyValue('order'));
+
+        assert_equals(order_value, -1, "Interpolation result for order should be rounded towards positive infinity");
+    },
+    test_description
+);
+</script>
diff --git a/css/css-values/integer_interpolation_round_half_towards_positive_infinity_z_index.html b/css/css-values/integer_interpolation_round_half_towards_positive_infinity_z_index.html
@@ -0,0 +1,38 @@
+<!doctype html>
+<title>Testing if integer interpolation is rounded towards positive infinity</title>
+<link rel="author" title="Joonghun Park" href="pjh0718@gmail.com">
+<link rel="help" href="https://drafts.csswg.org/css-values-4/#combine-integers">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+
+#anim-target {
+  animation: anim-z 4s steps(4) forwards 1;
+  animation-delay: -1s;
+  animation-play-state: paused;
+}
+
+@keyframes anim-z {
+  from {
+    z-index: -2;
+  }
+
+  to {
+    z-index: 0;
+  }
+}
+
+</style>
+<div id="anim-target"></div>
+<script>
+var test_description = "Integer interpolation should be rounded towards positive infinity";
+test(
+    t => {
+        const target = document.getElementById("anim-target");
+        const z_index_value = Number.parseFloat(getComputedStyle(target).getPropertyValue('z-index'));
+
+        assert_equals(z_index_value, -1, "Interpolation result for z-index should be rounded towards positive infinity");
+    },
+    test_description
+);
+</script>