Grapheme Cluster

Text shaping and editing is done on a per-grapheme-cluster basis, graphemes clusters are defined in "UAX #29 Unicode Text Segmentation".

Inside Hikogui a grapheme can be used in a std::basic_string. A grapheme is 21 bits, where grapheme clusters larger than one code-point get a temporary and unique-id assigned to the invalid unicode planes 17-31.

Text Style

A text-style is actually a set of styles for different text-categories, languages and scripts. The text-category is a mask, the language may be empty meaning a whildcard; and script may be 'zzzz' meaning a whildcard. This allows for at least one of the sub-styles to be a fallback.

filter:
- language code
- script code
- phrasing mask
font family id
font variant (weight/italic)
font size
color
lines (under / over / strike throught).

Attributed Grapheme Cluster

[63:48] Language code.
[47:36] Text style id.
[35:32] Text category.
[31:0] Grapheme cluster.

Phrasing

------------— | — | ---------------— Regular | \r | The default, neutral phrasing Emphesis | \e | Text with stressed emphesis. Spoken with clear articulation. Often shown in italic. Strong | \s | Text with more importance, warning, urgend. Spoken louder. Often shown in bold. Code | \c | A (sub-)expression of computer-language-code, Often shown in a non-proportional font. Abbreviation | \a | An abbreviation, shown in a different style to show there is a definition somehwere. Italic | \i | Show text in italic, without the text beging "emphesis" Bold | \b | Show text in bold, without the text being "strong" Citation | \q | A citation of a title, or a quote. Keyboard | \k | Used in help messages to show which key to press. Mark | \h | Used to highlight text, like using a physical yellow marker. Math | \m | A mathematical (sub-)expression. Often shown in a special italic math font. Unarticulated | \u | Unarticulated text. Often shown as regular underlined.

Rich Text format

--------------------— | ---------------------— \l{language} | Select ISO-639 language. \f{font-family-name}