Fixing Chinese Font Issues In Beamer Presentations

Hey guys! So, you're trying to jazz up your Beamer presentations with some Chinese text, huh? That's awesome! But, you've hit a snag with those missing bold and italic fonts, right? Don't worry, we've all been there. It's a common issue, and we're gonna dive deep into it. We will be exploring how to get those important font styles working in your Beamer presentations. This guide is tailored for those using XeLaTeX with the xeCJK package, specifically in the context of collegebeamer.sty. Let's get started and make your presentations shine!

The Problem: Chinese Font Styles Missing

Okay, so the core problem is this: you're using xeCJK to bring in those beautiful Chinese characters, but when you try to use bold or italic styles, things aren't working as expected. Let's break down why this happens and what's going on under the hood, and how to fix this situation. The main issue arises from how the xeCJK package interacts with different fonts and operating systems when creating Beamer presentations.

Understanding the Root Cause

The issue primarily stems from the availability (or lack thereof) of specific bold and italic font variations for the Chinese fonts you're trying to use. When you use \setCJKmainfont{<font>}, the xeCJK package tries to be smart and automatically find the bold and italic versions of that font. However, this automatic detection doesn't always work perfectly, especially with Chinese fonts.

OS-Specific Font Behavior

As the original poster pointed out, the behavior varies across different operating systems: Windows, macOS, and Linux. For example, on Windows, if you're using SimSun (a common font), there typically aren't dedicated bold and italic versions bundled with the font. This means that when you tell LaTeX to make text bold or italic, it might not know how to render it correctly. Whereas, on Linux, with fonts like Noto Serif CJK SC, you're more likely to find proper bold and italic variations, so it works like a charm!

The MWE Breakdown

The provided Minimal Working Example (MWE) perfectly illustrates the problem. It sets up a basic Beamer document and uses conditional statements (\ifwindows, \ifmacosx, \iflinux) to configure the Chinese font based on the operating system. Let's examine it:

\documentclass{beamer}

\usepackage{ifplatform}
\usepackage{xeCJK}
\ifwindows
    \setCJKmainfont{SimSun}
    % \setCJKmainfont{FandolSong} % font family with `-Regular`, `-Bold` as the suffix of regular, bold font. No italic font is included, either.
\fi
\ifmacosx
    \setCJKmainfont{Songti SC}
\fi
\iflinux
    \setCJKmainfont{Noto Serif CJK SC}
\fi

\begin{document}
\begin{frame}
正文内容。\textbf{正文内容。}\textit{正文内容。}
\end{frame}
\end{document}

The most important part here is how different fonts behave. On Windows, SimSun lacks dedicated bold and italic styles, so \textbf{正文内容。} and \textit{正文内容。} won't produce the desired effect. On macOS, Songti SC has similar issues. However, on Linux, Noto Serif CJK SC often has these styles, resolving the problem.

Potential Solutions for Chinese Font Styles

Alright, so now that we know what's going on, how do we fix it? Here are a few potential solutions you can try. We will break down each approach, and discuss the pros and cons of each method. These options offer a range of solutions, from the simple and straightforward to more advanced configurations, all aimed at ensuring your Chinese text displays correctly within your Beamer presentations.

1. Embrace Sans Serif Fonts

One straightforward approach is to ditch the serif fonts and go with a sans serif font. You can achieve this by simply not configuring any font with xeCJK, which leaves the default sans-serif font as the main font.

• How it Works: In this scenario, you'd only import the xeCJK package without setting a specific Chinese font. Beamer and XeLaTeX will then use the default sans-serif font, which generally has bold and italic variations available.
• Pros: This is the easiest and quickest solution. It requires no font configuration and solves the immediate problem. It also ensures consistent bold and italic styles since the default font supports them.
• Cons: You sacrifice the specific aesthetic you might have been aiming for with a serif font. Your presentation might look less traditional, especially if you have a strong preference for serif fonts.

2. Explicitly Declare Bold and Italic Fonts

This method involves explicitly telling xeCJK which fonts to use for bold and italic styles. We need to find the correct font names (this can vary by your system and font). Then, we will incorporate them into the \setCJKmainfont command.

• How it Works: First, you need to identify the exact font names for the bold and italic variations of your chosen Chinese font. You may need to look in your system's font viewer or use a font management tool. Once you have the names, you can use the optional arguments of \setCJKmainfont to specify these variations.
• Pros: This gives you complete control over the appearance of your bold and italic text. It's the most precise way to ensure your text looks exactly how you want it.
• Cons: This method requires you to know the font names and ensure they are installed on the system where the presentation will be viewed. It can be time-consuming to find the correct font names.

3. Implement Fake Bold and Slanted Types

If you can't find or don't want to use specific bold or italic fonts, you can use the package to simulate these styles. This means applying transformations to the regular font to make it look bold or italic.

• How it Works: LaTeX can simulate bold and italic styles by thickening and slanting the font. You can specify the 'fake bold' and 'fake italic' options within the \setCJKmainfont command.
• Pros: This is a simple fallback that works in most cases. It requires no specific font variations and will make text appear bold or italicized even if dedicated fonts aren't available.
• Cons: Fake bold and italic styles don't look as good as their dedicated counterparts. The result is often less visually appealing. The quality of the simulated styles can vary depending on the font.

Patching collegebeamer.sty

Since you are extending the template for your college, you might be considering patching collegebeamer.sty. This is a very viable option, especially if you want the solution to be consistent across all your presentations.

• How it Works: You can modify the collegebeamer.sty file to include explicit font configurations or to choose a default approach (like using sans-serif fonts). This ensures that all presentations created using the template will have the correct font styles.
• Pros: This provides a standardized solution for everyone using the template. It's the most convenient for your colleagues.
• Cons: You need to modify a style file, which requires understanding LaTeX and the template's structure. If the template is updated, you'll need to re-apply the patch.

Choosing the Right Approach

So, which solution is the best? It depends on your needs!

• For quick results and simplicity: The sans-serif option is the easiest.
• For precise control: Explicitly declaring the bold and italic fonts is the way to go (if you know the font names and they're available).
• As a fallback: Fake bold and slanted types can work.
• For a standardized solution: Patching the collegebeamer.sty is great.

Conclusion

So there you have it! We've covered the issue of missing bold and italic Chinese fonts in your Beamer presentations and offered a few solutions. The key is to understand what's happening under the hood (the OS and font variations), and then choose the method that best suits your needs. Whether you go with a simple sans-serif approach, meticulously define font styles, or patch the template, now you're well-equipped to make your presentations look amazing. Good luck, and happy TeXing!