[mathml] Bad automatic determination of form due to non-element nodes

Currently, Blink does not implement complete spec rules for determining the form of an <mo> element [1]. It just checks whether there are a nodes before or after the <mo> to calculate whether the form is prefix, infix or postfix. Once we support embellished operators [2], this will require a bigger code refactoring. Meanwhile, this CL fixes the common case where the <mo> has non-element nodes before or after it that must be ignored for the calculation of the form. This is visible on test #24 from Mozilla's MathML test [3] where the prefix/postfix form of "|" are stretchy but the non-stretchy infix form is used because of whitespace text nodes. Bug: 6606, 1121113, 1124301 [1] https://bugs.chromium.org/p/chromium/issues/detail?id=1121113 [2] https://bugs.chromium.org/p/chromium/issues/detail?id=1124298 [3] https://fred-wang.github.io/MathFonts/mozilla_mathml_test/ Change-Id: I42ff3b821d2f2da201b1ff4a4612a8d5756486a8
web-platform-tests · Aug 10, 2021 · 0871f23 · 0871f23
1 parent 4c5408d
commit 0871f23
Showing 1 changed file with 68 additions and 0 deletions.
diff --git a/mathml/presentation-markup/operators/mo-stretch-properties-001.html b/mathml/presentation-markup/operators/mo-stretch-properties-001.html
@@ -0,0 +1,68 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>Stretch properties</title>
+<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
+<link rel="help" href="https://w3c.github.io/mathml-core/#dictionary-based-attributes">
+<meta name="assert" content="Verify ">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/mathml/support/fonts.js"></script>
+<style>
+  math {
+      font: 25px/1 Ahem;
+  }
+  @font-face {
+      font-family: operators;
+      src: url("/fonts/math/operators.woff");
+  }
+  mo {
+      font-family: operators;
+  }
+</style>
+<script>
+  setup({ explicit_done: true });
+  window.addEventListener("load", () => { loadAllFonts().then(runTests); });
+
+  function runTests() {
+
+      var epsilon = 1;
+      var emToPx = 25;
+      var element;
+
+      test(function() {
+          element = document.getElementById("mn_vertical_line");
+          assert_approx_equals(element.getBoundingClientRect().height, 1 * emToPx, epsilon, "<mn> element");
+
+          element = document.getElementById("mo_prefix_vertical_line");
+          assert_approx_equals(element.getBoundingClientRect().height, 6 * emToPx, epsilon, "Prefix <mo> element");
+
+          element = document.getElementById("mo_infix_vertical_line");
+          assert_approx_equals(element.getBoundingClientRect().height, 1 * emToPx, epsilon, "Infix <mo> element");
+
+          element = document.getElementById("mo_postfix_vertical_line");
+          assert_approx_equals(element.getBoundingClientRect().height, 6 * emToPx, epsilon, "Postfix <mo> element");
+      }, `Stretchy vertical line`);
+
+      done();
+  }
+</script>
+</head>
+<body>
+  <div id="log"></div>
+  <p>
+    <math>
+      <mrow>
+        <!-- Some non-element nodes before -->
+        <mo id="mo_prefix_vertical_line" style="color: green">|</mo>
+        <mn id="mn_vertical_line">|</mn>
+        <mspace width="1em" height="3em" depth="3em" style="background: blue"/>
+        <mo id="mo_infix_vertical_line" lspace="0" rspace="0">|</mo>
+        <mo id="mo_postfix_vertical_line" style="color: green">|</mo>
+        <!-- Some non-element nodes after -->
+      </mrow>
+    </math>
+  </p>
+</body>
+</html>