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Rendering bug when Chinese chars in \text block #3224

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cesaryuan opened this issue May 2, 2024 · 2 comments
Open

Rendering bug when Chinese chars in \text block #3224

cesaryuan opened this issue May 2, 2024 · 2 comments
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Accepted Issue has been reproduced by MathJax team Code Example Contains an illustrative code example, solution, or work-around Merged Merged into develop branch Test Needed v4

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@cesaryuan
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cesaryuan commented May 2, 2024 •
edited
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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>
@dpvc dpvc added Accepted Issue has been reproduced by MathJax team v4 labels May 2, 2024
@dpvc
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dpvc commented May 2, 2024 •
edited
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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
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dpvc commented May 2, 2024

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 dpvc added the Code Example Contains an illustrative code example, solution, or work-around label May 2, 2024
dpvc added a commit to mathjax/MathJax-src that referenced this issue May 3, 2024
@dpvc
Fix handling of unknown characters in SVG output. (mathjax/MathJax#3224)
4945ed9
@dpvc dpvc mentioned this issue May 3, 2024
Merged
dpvc added a commit to mathjax/MathJax-src that referenced this issue Jun 4, 2024
@dpvc
Merge pull request #1089 from mathjax/issue3224
d6a9ee6 
Fix handling of unknown characters in SVG output. (mathjax/MathJax#3224)
@dpvc dpvc added Merged Merged into develop branch and removed Ready for Review labels Jun 4, 2024
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