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Fake bold fakebold ​

Intro ​

Fonts like SimSun, SimHei, and Kaiti from ZhongYi Electronics Co. only provide a single level of weight and cannot be bolded natively in Typst. With cuti, you can simulate fake bold by utilizing the stroke attribute of text.

When adding the stroke, cuti uses 0.02857em as its thickness, which is consistent with Microsoft Office softwares. (In fact, the exact value may be 1/35.)

Use fonts by scripts, including a single-weight Chinese font (Times New Roman + SimSun)

font: ("Times New Roman", "SimSun")

typst
#set text(font: ("Times New Roman", "SimSun"))
#grid(
    columns: 2,
    column-gutter: 0.2em,
    row-gutter: 0.6em,
    [Regular:], [你说得对，但是《Cuti》是一个用于伪粗体和伪斜体的包。],
    [Bold (Font Only):], text(weight: "bold")[你说得对，但是《Cuti》是一个用于伪粗体和伪斜体的包。],
    [Bold (Fake Only):], fakebold[你说得对，但是《Cuti》是一个用于伪粗体和伪斜体的包。],
    [Bold (Fake+Font):], show-cn-fakebold(text(weight: "bold")[你说得对，但是《Cuti》是一个用于伪粗体和伪斜体的包。]),
)

typst-demo

  • Regular

    Normal weight, as expected.

  • Bold (Font Only)

    Latin text uses the bold provided by Times New Roman, but Chinese text remains unchanged because SimSun lacks the bold variant.

  • Bold (Fake Only)

    Applies cuti's fake bold to both scripts. While effective for Chinese, it degrades Latin text, which already has a well-designed bold in Times New Roman.

  • Bold (Fake+Font)

    Latin text uses the bold provided by Times New Roman, and Chinese text uses cuti's fake bold because SimSun lacks the bold variant.

Use a multi-weight common font (Source Han Serif)

font: "Source Han Serif SC"

typst
#set text(font: "Source Han Serif SC")
#grid(
    columns: 2,
    column-gutter: 0.2em,
    row-gutter: 0.6em,
    [Regular:], [前面忘了。同时，逐步发掘「Typst」的奥妙。],
    [Bold (Font Only):], text(weight: "bold")[前面忘了。同时，逐步发掘「Typst」的奥妙。],
    [Bold (Fake Only):], fakebold[前面忘了。同时，逐步发掘「Typst」的奥妙。],
    [Bold (Fake+Font):], show-cn-fakebold(text(weight: "bold")[前面忘了。同时，逐步发掘「Typst」的奥妙。])
)

typst-demo

  • Regular

    Normal weight, as expected.

  • Bold (Font Only)

    Source Han Serif SC covers both scripts and provides the bold variant. Therefore, all texts are properly bolded.

  • Bold (Fake Only)

    Applies cuti's fake bold to both scripts. The result is degraded, especially for Latin text, since the font already provides a well-designed bold.

  • Bold (Fake+Font)

    Latin text uses the bold provided by the font, and Chinese text uses cuti's fake bold.

Quick Usage ​

typst
#import "@preview/cuti:0.3.0": show-cn-fakebold
#show: show-cn-fakebold

For most “academic” use cases, add the above code at the beginning of your document and set font using #set text(font: ("Times New Roman", "Chinese Font Name")). This allows you to bold Chinese characters. For example, SimSun + bold:

typst
#import "@preview/cuti:0.3.0": show-cn-fakebold
#set text(font: ("Times New Roman", "SimSun"))
+ Without `cuti`: 春江潮水连海平，*海上明月共潮生*。
#show: show-cn-fakebold
+ With `cuti`: 春江潮水连海平，*海上明月共潮生*。

typst-demo

TIP

In the example above, the Chinese font, SimSun, provides only a single weight, which normally prevents Chinese characters from being bolded in Typst. This is the primary use case for cuti.

Generally, if your Chinese font already provides multiple weights (such as Source Han Serif or Source Han Sans), there is no need to use cuti. Using cuti in such cases may cause the fake bold to be applied on top of the font-provided bold, which is visually unappealing.

To illustrate the possibility of this combination, the following examples use Source Han Serif as the default Chinese font, unless otherwise specified.

fakebold ​

#fakebold[] with no parmerter will apply the fakebold effect to characters.

typst
- Fakebold: #fakebold[#lorem(5)]
- Bold: #text(weight: "bold", lorem(5))
- Bold + Fakebold: #fakebold[#text(weight: "bold", lorem(5))]

typst-demo

#fakebold can accept the same parameters as #text.

  • The stroke parameter, if specified, will be ignored.
  • If the weight parameter is specified, it can be used to define which font weight to base the stroke on. The default is auto, and the options are auto, none, or an int/str representing font weight.
typst
- Regular: #lorem(5)
- Regular + Fakebold: #fakebold[#lorem(5)]
- Bold: #text(weight: "bold")[#lorem(5)]
- Bold + Fakebold: #fakebold(weight: "bold")[#lorem(5)]
- Bold + Fakebold: #set text(weight: "bold"); #fakebold[#lorem(5)]

typst-demo

Compatibility Note

cuti:^0.3.0 (compatible with Typst 0.12.0) retains base-weight as an alias for weight for backward compatibility, and base-weight has higher priority than weight.

In cuti:^0.2.1 (compatible with Typst 0.11.x), the default value of weight is none, indicating stroke based on current weight.

If the text is set to a color, the fake bold stroke will also change to the corresponding color.

typst
- Blue + Fakebold: #fakebold(fill: blue)[花生瓜子八宝粥，啤酒饮料矿泉水。#lorem(5)]
- Gradient + Fakebold: #set text(fill: gradient.conic(..color.map.rainbow)); #fakebold[花生瓜子八宝粥，啤酒饮料矿泉水。#lorem(5)]

typst-demo

regex-fakebold ​

The #regex-fakebold is designed to be used in multilingual and multi-font scenarios. It allows the use of a RegExp string as the reg-exp parameter to match characters that will have the fake bold effect applied. It can also accept the same parameters as #fakebold.

typst
+ RegExp `[a-o]`: #regex-fakebold(reg-exp: "[a-o]")[#lorem(5)]
+ RegExp `\p{script=Han}`: #regex-fakebold(reg-exp: "\p{script=Han}")[衬衫的价格是9磅15便士。]
+ RegExp `\p{script=Han}`: #set text(weight: "bold"); #regex-fakebold(reg-exp: "\p{script=Han}")[衬衫的价格是9磅15便士。]

typst-demo

In Example 3, 9 and 15 are the real bold characters from the font file, while the other characters are simulated as "fake bold" based on the regular weight.

show-fakebold ​

In multilingual and multi-font scenarios, different languages often utilize their own fonts, but not all fonts contain the bold weight. It can be inconvenient to use #fakebold or #regex-fakebold each time we require strong or bold effects. Therefore, the #show-fakebold function is introduced for show rule.

show-fakebold and regex-fakebold share the same parameters. By default:

  • show-fakebold uses ".+" as the regular expression, meaning all characters with bold or strong attributes will be fake-bolded;
  • show-fakebold uses weight: none as the default base weight:
    • In cuti:^0.2.1 (compatible with Typst 0.11.x), it will apply fake bold based on the current font weight.
    • In cuti:^0.3.0 (compatible with Typst 0.12.0), it will apply fake bold based on the regular font weight.
    • However, in all current versions, using #strong[] or its syntactic sugar *strong* for bold text will result in a base font weight of bold, and this behavior cannot be modified at the moment. (Feel free to submit a PR or open an issue if you have a solution.)
typst
#show: show-fakebold
- Regular: #lorem(10)
- Bold: #text(weight: "bold")[#lorem(10)]

typst-demo

Why the new version no longer defaults to boldening based on current weight

In Typst 0.11.x, boldening based on current weight generally didn't cause issues. However, in Typst 0.12.0, show rules might match already processed characters again, leading to infinite loops. Therefore, in cuti:0.3.0, cuti changed its default behavior.

Under normal circumstances, the combination of font-provided bold and fake bold is not the effect we want. Generally, we need to specify regular expressions to define the scope where fake bold should take effect.

typst
#show: show-fakebold.with(reg-exp: "\p{script=Han}")
- Regular: 我正在使用 Typst 排版。
- Strong: *我正在使用 Typst 排版。*

typst-demo

cn-fakebold & show-cn-fakebold ​

cn-fakebold and show-cn-fakebold are encapsulations of the above regex-fakebold and show-fakebold, pre-configured for use with Chinese text. Please refer to the Chinese documentation for detailed usage instructions.

Known Issues ​

Feel free to submit a PR or open an issue if you have a solution or better workaround.

When using strong for bold text, the base font weight is fixed at bold ​

typst
#show: show-cn-fakebold
- Regular: 滚滚长江东逝水，浪花淘尽英雄。 #lorem(5)
- Bold: #text(weight: "bold")[滚滚长江东逝水，浪花淘尽英雄。]
- Strong + Bug: *滚滚长江东逝水，浪花淘尽英雄。 #lorem(5)*

typst-demo

text.tracking may not work properly ​

typst
#set text(tracking: 1em)
滚滚长江#text(weight: "bold")[东逝水，浪花。]淘尽英雄

typst-demo

Stroke color is only guaranteed to work with simple settings ​

Ideally, the color of the fake bold stroke should match with the text.

typst
#show: show-cn-fakebold
#set text(fill: green)
*三月七日，沙湖道中遇雨*

typst-demo

However, cuti can only adapt to simple settings. If you use show "…", show regex(…), or other text-level rules to set text color, cuti may get the wrong context, resulting in mismatched stroke colors.

typst
#show: show-cn-fakebold
#show "同": set text(fill: purple)
#show regex("[\p{script=Han}]+"): set text(fill: red)
*雨具先去，同行皆狼狈，余独不觉*

typst-demo

Even changing the order of rules or adding function nesting cannot fix the stroke color, and may cause inconsistent styles.

typst
#show strong: it => {
  show regex("[\p{script=Han}]+"): set text(fill: red)
  it
}
#show: show-cn-fakebold
*莫听穿林打叶声，何妨吟啸且徐行。竹杖芒鞋轻胜马，谁怕？一蓑烟雨任平生。\ 料峭春风吹酒醒，微冷，山头斜照却相迎。回首向来萧瑟处，归去，也无风雨也无晴。*

typst-demo

Current workaround: Mark text.fill manually.

typst
#show: show-cn-fakebold
#show regex("[\p{script=Han}]+"): set text(green)
- *已而遂晴，故作此词*
- *#text(green)[已而遂晴]，#text(green)[故作此词]*

typst-demo