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Replace "cramped" with a new math-superscript-shift-style CSS property.
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w3c/mathml#164
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fred-wang committed Apr 1, 2020
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126 changes: 86 additions & 40 deletions index.html
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Expand Up @@ -2299,6 +2299,8 @@ <h4>Fractions <code>&lt;mfrac&gt;</code></h4>
<a><code>displaystyle</code></a> to <code>false</code>,
or if it was already <code>false</code> increments
<a><code>scriptlevel</code></a> by 1, within its children.
It sets <a>math-superscript-shift-style</a> to
<code>inline</code> within its second child.
To avoid visual confusion between the fraction bar and another
adjacent items (e.g. minus sign or another fraction's bar),
a default 1-pixel space is added around the element.
Expand All @@ -2319,7 +2321,9 @@ <h4>Fractions <code>&lt;mfrac&gt;</code></h4>
<div class="note" id="fraction-css-rules-on-children">
In practice, an <code>&lt;mfrac&gt;</code> element has two children
that are <a>in-flow</a>. Hence the CSS rules basically performs
<a><code>scriptlevel</code></a> and <a><code>displaystyle</code></a> changes for the <a>numerator</a> and
<a><code>scriptlevel</code></a>, <a><code>displaystyle</code></a>
and <a>math-superscript-shift-style</a>
changes for the <a>numerator</a> and
<a>denominator</a>.
</div>
<section id="fraction-with-nonzero-line-thickness">
Expand All @@ -2340,7 +2344,7 @@ <h5>Fraction with nonzero line thickness</h5>
<figcaption>Box model for the <code>&lt;mfrac&gt;</code> element</figcaption>
</figure>
<p>The <a>min-content inline size</a>
(respectively <a>max-content inline size</a>)
(respectively <a>max-content inline size</a>)
of content is the maximum between the
<a>min-content inline size</a>
(respectively <a>max-content inline size</a>) of the <a>numerator</a>'s
Expand Down Expand Up @@ -2567,13 +2571,16 @@ <h4>Radicals <code>&lt;msqrt&gt;</code>, <code>&lt;mroot&gt;</code></h4>
in <a href="#global-attributes"></a>.
</p>
<p>
The <code>&lt;msqrt&gt;</code> and <code>&lt;mroot&gt;</code>
elements sets <a>math-superscript-shift-style</a> to
<code>inline</code>.
The <code>&lt;mroot&gt;</code> element sets
increments <a><code>scriptlevel</code></a> by 2, and sets <a><code>displaystyle</code></a> to "false" in all
but its first child.
The <a href="#user-agent-stylesheet">user agent stylesheet</a>
must contain the following rule in order to implement that behavior:
</p>
<pre class="css" data-include="user-agent-stylesheet/mroot.css"></pre>
<pre class="css" data-include="user-agent-stylesheet/radicals.css"></pre>
<p>
If the <code>&lt;msqrt&gt;</code> or <code>&lt;mroot&gt;</code>
element do not have their computed
Expand Down Expand Up @@ -3505,27 +3512,6 @@ <h3>Script and Limit Schemata</h3>
These elements can be used to place limits on large operators, or fo
placing accents and lines above or below the base.
</p>
<section id="cramped-elements">
<h4>Cramped Elements</h4>
<p>
A <a>MathML Core element</a> is <dfn>cramped</dfn> if it satisfies
one of the following condition:
</p>
<ol>
<li>Its parent is <a>cramped</a> or a <a>radical element</a>.</li>
<li>It is the second <a>in-flow</a> child of an
<a><code>&lt;mfrac&gt;</code></a>,
<a><code>&lt;msub&gt;</code></a>,
<a><code>&lt;msubsup&gt;</code></a>,
<a><code>&lt;munder&gt;</code></a> or
<a><code>&lt;munderover&gt;</code></a> element.
</li>
</ol>
<div class="note" id="cramped-element">
The second <a>in-flow</a> child corresponds to a <a>numerator</a>, subscript or
underscript.
</div>
</section>
<section id="subscripts-and-superscripts-msub-msup-msubsup">
<h4>Subscripts and Superscripts <code>&lt;msub&gt;</code>, <code>&lt;msup&gt;</code>, <code>&lt;msubsup&gt;</code></h4>
<div class="issue" data-number="22">Use MathKernInfo?</div>
Expand Down Expand Up @@ -3706,9 +3692,10 @@ <h5>Base with superscript</h5>
</p>
<ul>
<li>The value <a>SuperscriptShiftUpCramped</a> if the
<code>&lt;msup&gt;</code> element is
<a>cramped</a> or
the value <a>SuperscriptShiftUp</a> otherwise.</li>
element has a computed
<a>math-superscript-shift-style</a> property equal to
<code>inline</code>, or
<a>SuperscriptShiftUp</a> otherwise.</li>
<li>
<a>SuperscriptBottomMin</a> + the <a>ink line-descent</a> of the
superscript's <a>margin box</a></li>
Expand Down Expand Up @@ -4648,20 +4635,42 @@ <h5>Base with prescripts and postscripts</h5>
</section>
</section>
<section>
<h4>Displaystyle and scriptlevel in scripts</h4>
<h4 id="displaystyle-and-scriptlevel-in-scripts">Displaystyle, scriptlevel and math-superscript-shift-style in scripts</h4>
<p>
For all MathML elements used for scripts and limits schemata,
the rule of thumb is to set
<a><code>displaystyle</code></a> to <code>false</code>
and to increment <a><code>scriptlevel</code></a> in all child
For all <a>scripted elements</a>, the rule of thumb is to set
<a><code>displaystyle</code></a> to <code>false</code> and
to increment <a><code>scriptlevel</code></a> in all child
elements but the first one.
However, when an overscript (respectively underscript)
has an <a href="#attribute-munderover-accent" class="internalDFN" data-link-type="dfn"><code>accent</code></a>
(respectively <a href="#attribute-munderover-accentunder" class="internalDFN" data-link-type="dfn"><code>accentunder</code></a>)
However, an <a><code>&lt;mover&gt;</code></a> (respectively
<a><code>&lt;munderover&gt;</code></a>)
element with an <a href="#attribute-munderover-accent" class="internalDFN" data-link-type="dfn"><code>accent</code></a>
attribute that is an
<a data-cite="INFRA#ascii-case-insensitive">ASCII case-insensitive</a>
match to <code>"true"</code> then
the <a><code>scriptlevel</code></a> is not incremented.
match to <code>"true"</code> does not increment scriptlevel within
its second child (respectively third child). Similarly,
<a><code>&lt;mover&gt;</code></a> and
<a><code>&lt;munderover&gt;</code></a> elements
with an <a href="#attribute-munderover-accent" class="internalDFN" data-link-type="dfn"><code>accentunder</code></a>
attribute that is an
<a data-cite="INFRA#ascii-case-insensitive">ASCII case-insensitive</a>
match to <code>"true"</code> do not increment scriptlevel within
their second child.
</p>
<p><code>&lt;mmultiscripts&gt;</code> sets
<a><code>math-superscript-shift-style</code></a> to
<code>inline</code> on its children at even position if they are
before an <a>&lt;mprescripts&gt;</a>, and on those at odd position
if they are after
an <a>&lt;mprescripts&gt;</a>. Other <a>scripted elements</a>
set <a><code>math-superscript-shift-style</code></a> to
<code>inline</code> on their second child.
An <a><code>&lt;mover&gt;</code></a> and
<a><code>&lt;munderover&gt;</code></a>
elements with an <a href="#attribute-munderover-accent" class="internalDFN" data-link-type="dfn"><code>accent</code></a>
attribute that is an
<a data-cite="INFRA#ascii-case-insensitive">ASCII case-insensitive</a>
match to <code>"true"</code> also sets <a><code>math-superscript-shift-style</code></a> to
<code>inline</code> within their first child.
</p>
<p>
The
Expand All @@ -4680,7 +4689,9 @@ <h4>Displaystyle and scriptlevel in scripts</h4>
this section are <a>in-flow</a> and the
<code>&lt;mprescript&gt;</code> is empty.
Hence the CSS rules essentially performs automatic <a><code>displaystyle</code></a> and
<a><code>scriptlevel</code></a> changes for the scripts.
<a><code>scriptlevel</code></a> changes for the scripts ; and
<a><code>math-superscript-shift-style</code></a> changes for
subscripts and sometimes the base.
</div>
</section>
</section>
Expand Down Expand Up @@ -5020,6 +5031,41 @@ <h3>The <code>math-style</code> property</h3>
layout should not take such constraints into consideration.
</p>
</section>
<section id="the-math-superscript-shift-style">
<h3>The <code>math-superscript-shift-style</code> property</h3>
<table>
<tbody>
<tr>
<th>Name:</th>
<td>
<dfn><code>math-superscript-shift-style</code></dfn>
</td>
</tr>
<tr><th>Value:</th><td><code>display | inline</code></td></tr>
<tr><th>Initial:</th><td><code>display</code></td></tr>
<tr><th>Applies to:</th><td>All elements</td></tr>
<tr><th>Inherited:</th><td>yes</td></tr>
<tr><th>Percentages:</th><td>n/a</td></tr>
<tr><th>Media:</th><td>visual</td></tr>
<tr><th>Computed value:</th><td>specified keyword</td></tr>
<tr><th>Canonical order:</th><td>n/a</td></tr>
<tr><th>Animation type:</th><td>not animatable</td></tr>
</tbody>
</table>
<p>
If the value of <code>math-superscript-shift-style</code> is <code>inline</code>, the math layout on descendants will use the
<a>superscriptShiftUpCramped</a> parameter to place superscript.
If the value of <code>math-superscript-shift-style</code> is <code>display</code>, the math
will use the <a>superscriptShiftUp</a> parameter instead.
</p>
<p>
This property is used for positioning superscript during the layout
of MathML <a>scripted elements</a>.
See § <a href="#subscripts-and-superscripts-msub-msup-msubsup"></a>
<a href="#prescripts-and-tensor-indices-mmultiscripts"></a> and
<a href="#underscripts-and-overscripts-munder-mover-munderover"></a>.
</p>
</section>
<section id="the-math-script-level-property">
<h3>The <code>math-script-level</code> property</h3>
<table>
Expand Down Expand Up @@ -5650,8 +5696,8 @@ <h2>User Agent Stylesheet</h2>
<span data-include-replace="true" data-include="user-agent-stylesheet/mtable.css"></span><span data-include-replace="true" data-include="user-agent-stylesheet/mtable-frame.css"></span><span data-include-replace="true" data-include="user-agent-stylesheet/mtr.css"></span><span data-include-replace="true" data-include="user-agent-stylesheet/mtd.css"></span>
/* Fractions */
<span data-include-replace="true" data-include="user-agent-stylesheet/mfrac.css"></span>
/* Other rules for scriptlevel and displaystyle */
</span><span data-include-replace="true" data-include="user-agent-stylesheet/mroot.css"></span><span data-include-replace="true" data-include="user-agent-stylesheet/scripts.css"></span>
/* Other rules for scriptlevel, displaystyle and math-superscript-shift-style */
</span><span data-include-replace="true" data-include="user-agent-stylesheet/radicals.css"></span><span data-include-replace="true" data-include="user-agent-stylesheet/scripts.css"></span>
</pre>
</section>
<section class="normative">
Expand Down
1 change: 1 addition & 0 deletions user-agent-stylesheet/math.css
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Expand Up @@ -5,6 +5,7 @@ math {
font-style: normal;
font-family: math;
math-style: inline;
math-superscript-shift-style: display;
math-script-level: initial;
}
math[display="block" i] {
Expand Down
3 changes: 3 additions & 0 deletions user-agent-stylesheet/mfrac.css
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Expand Up @@ -6,3 +6,6 @@ mfrac > * {
math-script-level: auto;
math-style: inline;
}
mfrac > :nth-child(2) {
math-superscript-shift-style: inline;
}
3 changes: 3 additions & 0 deletions user-agent-stylesheet/mroot.css → user-agent-stylesheet/radicals.css
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Expand Up @@ -2,3 +2,6 @@ mroot > :not(:first-child) {
math-script-level: add(2);
math-style: inline;
}
mroot, msqrt {
math-superscript-shift-style: inline;
}
15 changes: 15 additions & 0 deletions user-agent-stylesheet/scripts.css
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Expand Up @@ -14,3 +14,18 @@ munderover[accentunder="true" i] > :nth-child(2),
munderover[accent="true" i] > :nth-child(3) {
math-script-level: inherit;
}
msub > :nth-child(2),
msup > :nth-child(2),
msubsup > :nth-child(2),
munder > :nth-child(2),
mover > :nth-child(2),
munderover > :nth-child(2),
mmultiscripts > :nth-child(even),
mmultiscripts > mprescripts ~ *:nth-child(odd),
mover[accent="true" i] > :first-child,
munderover[accent="true" i] > :first-child {
math-superscript-shift-style: inline;
}
mmultiscripts > mprescripts ~ *:nth-child(even) {
math-superscript-shift-style: inherit;
}

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