[@layer] Use layer order to resolve @Property and @scroll-timeline na…

…me conflicts This patch adds a new class AtRuleCascadeMap, a miniature CascadeMap, to cascade @Property and @scroll-time rules across origins and cascade layers. We can't use it to cascade other name-defining at-rules because: - @font-face rules with the same 'font-family' may co-exist - @counter-style and @Keyframes rules are managed per tree scope, and allow the "append-only" update in Blink Bug: 1095765 Change-Id: Iec5dad0b932b1aed6e9c18bca9da1443e2d1fd88 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3152514 Commit-Queue: Xiaocheng Hu <[email protected]> Reviewed-by: Anders Hartvoll Ruud <[email protected]> Cr-Commit-Position: refs/heads/main@{#920947}
web-platform-tests · Sep 13, 2021 · f4f3076 · f4f3076
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diff --git a/css/css-cascade/layer-property-override.html b/css/css-cascade/layer-property-override.html
@@ -0,0 +1,154 @@
+<!DOCTYPE html>
+<title>Resolving @property name conflicts with cascade layers</title>
+<link rel="help" href="https://drafts.csswg.org/css-cascade-5/#layering">
+<link rel="author" href="mailto:[email protected]">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+#target, #reference {
+  width: 100px;
+  height: 100px;
+}
+
+#reference {
+  background-color: green;
+}
+</style>
+
+<div id="target"></div>
+<div id="reference"></div>
+
+<script>
+// In all tests, background color of #target should be green, same as #reference
+
+const testCases = [
+  {
+    title: '@property layered overrides unlayered',
+    style: `
+      #target {
+        background-color: var(--foo);
+      }
+
+      @layer {
+        @property --foo {
+          syntax: '<color>';
+          inherits: false;
+          initial-value: green;
+        }
+      }
+
+      @property --foo {
+        syntax: '<color>';
+        inherits: false;
+        initial-value: red;
+      }
+    `
+  },
+
+  {
+    title: '@property override between layers',
+    style: `
+      @layer base, override;
+
+      #target {
+        background-color: var(--foo);
+      }
+
+      @layer override {
+        @property --foo {
+          syntax: '<color>';
+          inherits: false;
+          initial-value: green;
+        }
+      }
+
+      @layer base {
+        @property --foo {
+          syntax: '<color>';
+          inherits: false;
+          initial-value: red;
+        }
+      }
+    `
+  },
+
+  {
+    title: '@property override update with appended sheet 1',
+    style: `
+      @layer base, override;
+
+      #target {
+        background-color: var(--foo);
+      }
+
+      @layer override {
+        @property --foo {
+          syntax: '<color>';
+          inherits: false;
+          initial-value: green;
+        }
+      }
+    `,
+    append: `
+      @layer base {
+        @property --foo {
+          syntax: '<color>';
+          inherits: false;
+          initial-value: red;
+        }
+      }
+    `
+  },
+
+  {
+    title: '@property override update with appended sheet 2',
+    style: `
+      @layer base, override;
+
+      #target {
+        background-color: var(--foo);
+      }
+
+      @layer base {
+        @property --foo {
+          syntax: '<color>';
+          inherits: false;
+          initial-value: red;
+        }
+      }
+    `,
+    append: `
+      @layer override {
+        @property --foo {
+          syntax: '<color>';
+          inherits: false;
+          initial-value: green;
+        }
+      }
+    `
+  },
+];
+
+for (let testCase of testCases) {
+  var documentStyle = document.createElement('style');
+  documentStyle.appendChild(document.createTextNode(testCase['style']));
+  document.head.appendChild(documentStyle);
+
+  var appendedStyle;
+  if (testCase['append']) {
+    document.body.offsetLeft;  // Force style update
+    appendedStyle = document.createElement('style');
+    appendedStyle.appendChild(document.createTextNode(testCase['append']));
+    document.head.appendChild(appendedStyle);
+  }
+
+  test(function () {
+    assert_equals(getComputedStyle(target).backgroundColor,
+                  getComputedStyle(reference).backgroundColor);
+  }, testCase['title']);
+
+  if (appendedStyle)
+    appendedStyle.remove();
+  documentStyle.remove();
+}
+</script>
diff --git a/css/css-cascade/layer-scroll-timeline-override.html b/css/css-cascade/layer-scroll-timeline-override.html
@@ -0,0 +1,183 @@
+<!DOCTYPE html>
+<title>Resolving @scroll-timeline name conflicts with cascade layers</title>
+<link rel="help" href="https://drafts.csswg.org/css-cascade-5/#layering">
+<link rel="author" href="mailto:[email protected]">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/web-animations/testcommon.js"></script>
+<style>
+#scroller {
+  overflow: scroll;
+  width: 100px;
+  height: 100px;
+}
+
+#scroller div {
+  height: 200px;
+}
+
+@keyframes expand {
+  from { width: 100px; }
+  to { width: 200px; }
+}
+
+#target, #reference {
+  height: 100px;
+}
+
+#reference {
+  width: 150px;
+}
+
+#target {
+  animation: expand 10s linear;
+  height: 100px;
+}
+</style>
+
+<div id="scroller">
+  <div></div>
+</div>
+<div id="target"></div>
+<div id="reference"></div>
+
+<script>
+// In all tests, width of #target should be 150px, same as #reference
+
+const testCases = [
+  {
+    title: '@scroll-timeline layered overrides unlayered',
+    style: `
+      #target {
+        animation-timeline: timeline;
+      }
+
+      @layer {
+        @scroll-timeline timeline {
+          source: selector(#scroller);
+          start: 0px;
+          end: 50px;
+        }
+      }
+
+      @scroll-timeline timeline {
+        source: selector(#scroller);
+        start: 0px;
+        end: 100px;
+      }
+    `
+  },
+
+  {
+    title: '@scroll-timeline override between layers',
+    style: `
+      @layer base, override;
+
+      #target {
+        animation-timeline: timeline;
+      }
+
+      @layer override {
+        @scroll-timeline timeline {
+          source: selector(#scroller);
+          start: 0px;
+          end: 50px;
+        }
+      }
+
+      @layer base {
+        @scroll-timeline timeline {
+          source: selector(#scroller);
+          start: 0px;
+          end: 100px;
+        }
+      }
+    `
+  },
+
+  {
+    title: '@scroll-timeline override update with appended sheet 1',
+    style: `
+      @layer base, override;
+
+      #target {
+        animation-timeline: timeline;
+      }
+
+      @layer override {
+        @scroll-timeline timeline {
+          source: selector(#scroller);
+          start: 0px;
+          end: 50px;
+        }
+      }
+    `,
+    append: `
+      @layer base {
+        @scroll-timeline timeline {
+          source: selector(#scroller);
+          start: 0px;
+          end: 100px;
+        }
+      }
+    `
+  },
+
+  {
+    title: '@scroll-timeline override update with appended sheet 2',
+    style: `
+      @layer base, override;
+
+      #target {
+        animation-timeline: timeline;
+      }
+
+      @layer base {
+        @scroll-timeline timeline {
+          source: selector(#scroller);
+          start: 0px;
+          end: 100px;
+        }
+      }
+    `,
+    append: `
+      @layer override {
+        @scroll-timeline timeline {
+          source: selector(#scroller);
+          start: 0px;
+          end: 50px;
+        }
+      }
+    `
+  },
+];
+
+for (let testCase of testCases) {
+  promise_test(async function() {
+    assert_true(
+      CSS.supports('animation-timeline', 'foo'),
+      'This test requires @scroll-timeline support');
+
+    var documentStyle = document.createElement('style');
+    documentStyle.appendChild(document.createTextNode(testCase['style']));
+    document.head.appendChild(documentStyle);
+
+    var appendedStyle;
+    if (testCase['append']) {
+      document.body.offsetLeft;  // Force style update
+      appendedStyle = document.createElement('style');
+      appendedStyle.appendChild(document.createTextNode(testCase['append']));
+      document.head.appendChild(appendedStyle);
+    }
+
+    scroller.scrollTop = 25;
+    await waitForNextFrame();
+    assert_equals(getComputedStyle(target).width,
+                  getComputedStyle(reference).width);
+
+    if (appendedStyle)
+      appendedStyle.remove();
+    documentStyle.remove();
+  }, testCase['title']);
+}
+</script>