Chiron Sung HK: a typeface for Traditional Chinese users
=======================

[中文版説明請按此 / Click here for the Chinese README](README.md)

Chiron Sung HK (昭源宋體) is a Traditional Chinese serif typeface based on [Adobe](https://adobe.com/)’s [Source Han Serif](https://github.com/adobe-fonts/source-han-serif) (branded as [Noto Sans CJK](https://github.com/googlefonts/noto-cjk/) by [Google](https://www.google.com)). The font aims to provide a modern, region-agnostic glyph set that adopts the “modern” glyph style similar to the prevailing, usually commercial, typefaces in Traditional Chinese regions.

Also check out [Chiron Hei HK](https://github.com/chiron-fonts/chiron-hei-hk/), the complementary sans-serif typeface for Chiron Sung HK.

*Note: As this font targets Traditional Chinese users, the [website](https://chiron-fonts.github.io/) and the [CHANGELOG](CHANGELOG.md) details are available in Traditional Chinese only.* 

## Usage

### For desktop

Download the font from the [Github Releases](https://github.com/chiron-fonts/chiron-sung-hk/releases/latest) page and install it. The font comes with various configurations:
* OpenType format, static instances (`STATIC_OTF/` directory)
* TrueType format, static instances (`STATIC_TTF/` directory)
* Variable Font in OpenType format (`VAR_OTF/` directory)
* Variable Font in TrueType format (`VAR_TTF/` directory)
* Webfont version in OpenType WOFF2 format (`WOFF2_OTF/` directory)
* Webfont version in TrueType WOFF2 format (`WOFF2_TTF/` directory)

The font family name is *Chiron Sung HK* for static instances, and *Chiron Sung HK VF* for the variable font configuration. Use the *Chiron Sung HK WS* font family name for the webfont version (see below).

### For web

Besides manually downloading the font from the GitHub Releases page, there are two alternative ways to access the webfont version of Chiron Sung HK.

1. Self-hosting

Install the [chiron-sung-hk-webfont npm package](https://www.npmjs.com/package/chiron-sung-hk-webfont) and import the CSS files. For example: 

```css
@import '~chiron-sung-hk-webfont/css/vf.css';
@import '~chiron-sung-hk-webfont/css/vf-italic.css';
```

For TrueType outline, install the [chiron-sung-hk-webfont-truetype npm package](https://www.npmjs.com/package/chiron-sung-hk-webfont-truetype) instead, and change the import module name from `chiron-sung-hk-webfont` to `chiron-sung-hk-webfont-truetype`.

2. CDN

Visit the [jsDeliver](https://www.jsdelivr.com/package/npm/chiron-sung-hk-webfont?path=css) webpage, add the desired font styles to the collection, and retrieve the CSS import statements. *Note: do not enable the option that will merge all the selected styles into a single file. This will not work.* 

Usage example in CSS:

```css
body {
    font-family: "Chiron Sung HK WS"; /* Note the font name. */
    font-weight: 310; /* Any number between 200 and 900. */
    font-style: normal; /* normal or italic. */
    font-variation-settings: "PADG" 4; /* Any number between 0 and 10. */
}
```

## Comparison with Upstream 

![Alt text](images/diff-glyphs.webp)

Chiron Sung HK is based on the Traditional Chinese (Hong Kong) variant of Source Han Serif *(the upstream)*. Here’s a comparison to illustrate the features of Chiron Sung HK:

### Glyph shapes

Glyphs of Big Five and HKSCS-2016 character sets for Source Han Serif Traditional Chinese (Hong Kong) are designed in accordance with the [Reference Glyphs for Chinese Computer Systems in Hong Kong
](https://www.ccli.gov.hk/en/download/reference_glyphs.html). In my opinion it is a little too fastidious about asking the printed form of a character to follow how it is written by hand.

Chiron Sung HK takes references from the commercial typefaces commonly seen in Hong Kong, which emphasizes overall aesthetics for printing and display. While Chiron Sung HK doesn’t strictly adhere to a single standard (de facto or not), its chosen glyph form is widely recognized by the Traditional Chinese community.

Over 6,000 glyphs have been remapped or modified. Check out [UpstreamDifferences.pdf](resources/UpstreamDifferences.pdf) for details on the changes.

### `Locl` GSUB feature

Chiron Sung HK covers all codepoints in the **language-specific** configuration of Source Han Serif Traditional Chinese (Hong Kong). However, it does not support the `locl` (localized forms) feature of the original typeface. Only the default, opinionated set of glyph shapes will be available. Glyphs specific to other regions are removed.

### Full-width punctuations adjustment

![Alt text](images/diff-punc.webp)

* Full-width punctuation shapes have been slightly adjusted.
* `‘`, `’`, `“` and `”` now default to their proportional version.      
* Full-width versions of `⸺` (U+2E3A) and `⸻` (U+2E3B) are provided by default.
* Opentype instructions `halt` `vhal` `palt` `vpal` for full-width punctuations have been removed. 

### Character additions (Chinese)

![Alt text](images/diff-additions.webp)

Over a thousand Chinese character glyphs have been added, including amendments after the publishing of HKSCS-2016.

Again, check out [UpstreamDifferences.pdf](resources/UpstreamDifferences.pdf) for details.

### LGC letters

The full set of [Source Serif](https://github.com/adobe-fonts/source-serif) has been incorporated. Note that the scaling factor of the LGC characters in Chiron Sung HK is different from the upstream, so it is not a drop-in replacement of the latter. 

### Italic style

![Alt text](images/diff-italics.webp)

Source Han Serif does not have a true italic font configuration. Chiron Sung HK provides an italic style by slanting the original (non-LGC) glyphs and then incorporating the Source Serif italic typeface. 

### Font weight and naming

The static font families, Chiron Sung HK and Chiron Sung HK Text, use abbreviated weight names for better compatibility with certain operating systems. The variable font version (Chiron Sung HK VF) adopts the long weight names as its upstream.

| Chiron Sung HK/HK Text | Chiron Sung HK VF | Weight Axis Value |
|------------------------|-------------------|-------------------|
| EL                     | ExtraLight        | 200               |
| L                      | Light             | 300               |
| N                      | Normal            | 350               |
| R                      | Regular           | 400               |
| M                      | Medium            | 500               |
| SB                     | SemiBold          | 600               |
| B                      | Bold              | 700               |
| H                      | Heavy             | 900               |

Note that the “Normal” font weight is not present in the upstream.

### Additional “PADG” axis (variable font only)

Chiron Sung HK introduces a new “PADG” axis alongside the original “wght” axis in the variable font. This “PADG” axis allows you to control the area ratio decrement of Han/Kanji characters relative to the upstream.

The “PADG” axis changes the glyph contour without affecting other measurement data will be affected. A value of 0 means no decrement, while setting it to 10 will shrink the character size by approximately 5%. 

### Additional “Text” subfamily

![Alt text](images/diff-text.webp)

This subfamily is created by converting the variable instance of different weights with `PADG` axis set to 6 to static instances.

The “Text” subfamily is created by converting variable font instances with the “PADG” axis set to 6 into static instances. By moderately shrinking the Han/Kanji characters, the “Text” subfamily provides more space between Chinese characters, making it suitable for body text typesetting.

### Glyph optimization for SemiBold instance

A SemiBold master has been added to a small number of frequently accessed characters.

## License

Chiron Sung HK is available under the OFL-1.1 License, allowing free use for both commercial and non-commercial purposes. Refer to [LICENSE.md](LICENSE.md) for details.

## Donation

If you’re satisfied with my work, consider buying me a drink through [Paypal.me](https://www.paypal.com/paypalme/tamcyhk). Your support is greatly appreciated!