mathml/presentation-markup/fractions/frac-parameters-gap-005.html

<!DOCTYPE html>
<html class="reftest-wait">
<head>
<meta charset="utf-8">
<title>Stack parameters (display gap between numerator and denominator)</title>
<link rel="help" href="https://w3c.github.io/mathml-core/#fractions-mfrac">
<link rel="match" href="frac-parameters-gap-005-ref.html"/>
<meta name="assert" content="Element mfrac with zero linethickness correctly uses the StackDisplayStyleGapMin parameter from the MATH table when denominator contains text.">
<style>
  math, mspace, mtext {
    font-size: 20px;
  }
  mtext {
    font-family: math-text;
    color: blue;
  }
  @font-face {
    font-family: displaystylegapmin4000;
    src: url("/fonts/math/stack-displaystylegapmin4000.woff");
  }
  @font-face {
    /*
      math-text has the following properties:
      - typo/hhea/win metrics: 2.5em ascent and 2.5em descent.
      - glyph A: .5em ascent and .5em descent.
      - glyph B: 1em ascent and 0em descent.
      - glyph C: 0em ascent and 1em descent.
     */
    font-family: math-text;
    src: url("/fonts/math/math-text.woff");
  }
  #reference {
    background: green;
  }
  #frame {
    position: absolute;
    border-top: 4px solid black;
    border-bottom: 4px solid black;
    width: 100%;
  }
</style>
<script src="/mathml/support/fonts.js"></script>
<script>
  function runTests() {
    var div = document.getElementById("frame");
    var refBox = document.getElementById("reference").getBoundingClientRect();
    div.style.top = `${refBox.top-2}px`;
    div.style.height = `${refBox.height-4}px`;
    document.documentElement.classList.remove('reftest-wait');
  }
  window.addEventListener("load", () => { loadAllFonts().then(runTests); });
</script>
</head>
<body>
  <p>
    This test passes if the blue squares are aligned:
  </p>
  <p>
    <math display="block" style="font-family: displaystylegapmin4000">
      <!-- This is a dummy mspace element to ensure that the font ascent/descent does not affect the size of the math element. -->
      <mspace height="10em" depth="10em"/>
      <!--
           The gap between the numerators/denominators and the math axis must StackDisplayStyleGapMin / 2.
           The gap should be calculated using the exact bounding box of the glyphs.
           The numerator descent is .5em + the denominator ascent.
           Hence glyphs A, B, C should be rendered at the same vertical position, even if they have different ascent/descent.
        -->
      <mfrac linethickness="0px">
        <mspace width="3em" depth="1em"/>
        <mspace id="reference" width="3em" height=".5em" depth=".5em"/>
      </mfrac>
      <mfrac linethickness="0px">
        <mspace width="3em" depth="1em"/>
        <mtext>A</mtext>
      </mfrac>
      <mfrac linethickness="0px">
        <mspace width="3em" depth="1.5em"/>
        <mtext>B</mtext>
      </mfrac>
      <mfrac linethickness="0px">
        <mspace width="3em" depth=".5em"/>
        <mtext>C</mtext>
      </mfrac>
    </math>
  </p>
  <div id="frame"></div>
  <script src="/mathml/support/feature-detection.js"></script>
  <script>MathMLFeatureDetection.ensure_for_match_reftest("has_mfrac");</script>
</body>
</html>