Katex: \not broken with new spacing code

[edemaine]

0.9.0 seems to have introduced a bug in this simple example: \not E

0.9.0 renders as follows:

<span class="katex-html" aria-hidden="true">
  <span class="strut" style="height:0.69444em;"></span>
  <span class="strut bottom" style="height:0.8888799999999999em;vertical-align:-0.19444em;"></span>
  <span class="base">
    <span class="mrel latin_fallback" style="position:absolute;padding-left:0.8em;"≯</span>
    <span class="mord rule" style="margin-right:0.2777777777777778em;"></span>
    <span class="mord mathit" style="margin-right:0.05764em;">E</span>
  </span>
</span>

0.9.0-alpha2 (as on the current demo site) renders correctly:

<span class="katex-html" aria-hidden="true">
  <span class="strut" style="height:0.69444em;"></span>
  <span class="strut bottom" style="height:0.8888799999999999em;vertical-align:-0.19444em;"></span>
  <span class="base">
    <span class="mord mathit" style="padding-left:0.277771em;position:relative;">
      <span class="mainrm" style="position:absolute;right:0;"≯</span>
      <span class="mord mathit" style="margin-right:0.05764em;">E</span>
    </span>
  </span>
</span>

[kevinbarabash]

We should add a screenshot test case for this so we don't regress in the future.

[kevinbarabash]

@edemaine I forgot that we do have screenshot tests for this. This bug seems to be Safari only. Can you confirm what browser you're seeing this in?

[edemaine]

@kevinbarabash I just confirmed that the issue is present on Chrome 65.0.3325.181 for Windows on the current demo site (0.9.0).

[kevinbarabash]

Interesting. It works fine for me in Chrome 66 on Mac. In makeFF it looks like we're using the combining version and we're setting a negative left start bearing on the character which is probably what's causing the issue.

[kevinbarabash]

I've created https://github.com/KaTeX/katex-fonts/issues/44 to track fixing this.

[edemaine]

Just updated to 66.0.3359.117 and same issue. Weird. So maybe specific to Chrome for Windows? And I assume you're seeing it on Safari too?

Anyway, we/you moved all the other accents over to noncombining characters to avoid Safari issues, so probably should do the same for \not...

[kevinbarabash]

I'm seeing the issue on Safari.

[edemaine]

Actually, I tried this on quicklatex, and maybe the new behavior is actually the correct one! (matching LaTeX)

[kevinbarabash]

@edemaine \not= is totally wrong. It renders as = / in Safari so I think we still need a fix for this, as least for Safari.

[riteme]

Hello, I'm using Chrome 67.0.3396.99 on Ubuntu 18.04 and I found that there seems to be a similar issue with \not\mid.

So does \not E, whose output looks like the first image in this issue. But KaTeX works fine for \not=, \not\equiv, \not<.

I have also tried Firefox 61.0.1 and got the same result.

[edemaine]

@riteme That is the intended behavior of \not -- it's how it works in LaTeX. Here's a rendering from quicklatex.com:

\begin{align*}
\not| \\
\nmid \\
\not\mid
\end{align*}

[riteme]

@edemaine That's strange... I have just switched to KaTeX from MathJax. It seems that MathJax simply translates \not\mid into \nmid.

[edemaine]

Thanks @riteme for the heads up. This does seem to be a difference between LaTeX and MathJax. In these situations, we generally prefer to match LaTeX, in particular so that someone converting code from KaTeX to LaTeX will not have any surprises.