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Rendering bug when Chinese chars in \text block #3224

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Rendering bug when Chinese chars in \text block#3224
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AcceptedIssue has been reproduced by MathJax teamCode ExampleContains an illustrative code example, solution, or work-aroundMergedMerged into develop branchTest Neededv4
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v4.0
@cesaryuan

Description

@cesaryuan
cesaryuan
opened on May 2, 2024 · edited by cesaryuan

Issue Summary

There is a rendering bug when Chinese chars in \text block. The affected version is 4.0.0-beta.6. And the 3.2.2 version is fine.

Steps to Reproduce:

  1. Open the following html, as you can see, Chinese \text block is rendered wrong.
<!DOCTYPE html>
<html>

<head>
    <title>Mathjax tex-mml-svg bug</title>
    <script src="https://cdn.jsdelivr.net/npm/mathjax@4.0.0-beta.6/tex-mml-svg.js" id="MathJax-script"></script>
</head>

<body>
    <p>Rendering bug when Chinese chars in \text block: $$\text{中文 bug}$$</p>
    <p>Latin chars is fine: $$\text{adwaw da ai dawd,}$$</p>
    <p>Version 3.2.2 is also fine</p>
</body>

</html>

image

image

Technical details:

  • MathJax Version: 4.0.0-beta.6
  • Client OS: Windows 11
  • Browser: Chrome 124.0.6367.63

I am using the default MathJax configuration:

and loading MathJax via

<script src="https://cdn.jsdelivr.net/npm/mathjax@4.0.0-beta.6/tex-mml-svg.js" id="MathJax-script"></script>

Supporting information:

<!DOCTYPE html>
<html>

<head>
    <title>Mathjax tex-mml-svg bug</title>
    <script src="https://cdn.jsdelivr.net/npm/mathjax@4.0.0-beta.6/tex-mml-svg.js" id="MathJax-script"></script>
</head>

<body>
    <p>Rendering bug when Chinese chars in \text block: $$\text{中文 bug}$$</p>
    <p>Latin chars is fine: $$\text{adwaw da ai dawd,}$$</p>
    <p>Version 3.2.2 is also fine</p>
</body>

</html>

Activity

dpvc
added
AcceptedIssue has been reproduced by MathJax team
v4
on May 2, 2024
dpvc

dpvc commented on May 2, 2024

@dpvc
dpvc
on May 2, 2024 · edited by dpvc
Member

Thanks for the report.

The easiest solution is to set the mtextInheritFont option to true in the output block of your configuration:

MathJax = {
  output: {
    mtextInheritFont: true
  }
};

If you want the non-Chinese text to be in the default MathJax font, then you can use the following patch instead:

MathJax = {
  startup: {
    ready() {
      const {SvgWrapper} = MathJax._.output.svg.Wrapper;
      SvgWrapper.prototype.placeChar = function (n, x, y, parent, variant = null, buffer = false) {
        if (variant === null) {
          variant = this.variant;
        }
        const C = n.toString(16).toUpperCase();
        const [ , , w, data] = this.getVariantChar(variant, n);
        if (data.unknown) {
          this.utext += String.fromCodePoint(n);
          return (buffer ? 0 : this.addUtext(x, y, parent, variant));
        }
        const dx = this.addUtext(x, y, parent, variant);
        if ('p' in data) {
          x += dx;
          const path = (data.p ? 'M' + data.p + 'Z' : '');
          this.place(x, y, this.adaptor.append(parent, this.charNode(variant, C, path)));
          return w + dx;
        }
        if ('c' in data) {
          const g = this.adaptor.append(parent, this.svg('g', {'data-c': C}));
          this.place(x, y, g);
          x = 0;
          for (const n of this.unicodeChars(data.c, variant)) {
            x += this.placeChar(n, x, y, g, variant);
          }
          return w + x + dx;
        }
        return w;
      };
      MathJax.startup.defaultReady();
    }
  }
};

The problem was that the placeChar() function wasn't handling characters that are not in the MathJax font properly (it did not process their widths correctly) in SVG output. This corrected routine should do the job.

I will make a PR to fix the problem in the next release.

dpvc

dpvc commented on May 2, 2024

@dpvc
dpvc
on May 2, 2024
Member

Sorry, I had mistyped mtextInheritFont in the first code block above. I have fixed it, so make sure you have the correct version if you use that.

dpvc
added
Code ExampleContains an illustrative code example, solution, or work-around
on May 2, 2024
dpvc
added a commit that references this issue on May 3, 2024

Fix handling of unknown characters in SVG output. (mathjax/MathJax#3224)

4945ed9
dpvc
mentioned this on May 3, 2024
dpvc
added
Ready for Review
Test Needed
on May 3, 2024
dpvc
added a commit that references this issue on Jun 4, 2024

Merge pull request #1089 from mathjax/issue3224

d6a9ee6
dpvc
added
MergedMerged into develop branch
and removed
Ready for Review
on Jun 4, 2024
dpvc
added this to the v4.0 milestone on Feb 28, 2025
cesaryuan
closed this as completedon Apr 9, 2025
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          Rendering bug when Chinese chars in \text block · Issue #3224 · mathjax/MathJax