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

language-code 15
country-code 10
phrasing 4
grapheme 21
text-style 15.
[63:48] Language code.
[47:36] Text style id.
[35:32] Text category.
[31:0] Grapheme cluster.

Phrasing

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

Aux Text format

State machine

The state-machine has the following variables:

text-style
phrasing
language
font-size
font (selected using font-family, weight and italic-flag)
color
set of masks

Format EBNF

document := part*
 
part := text | command
 
text := /[^[]+/
 
// Emits a single '['
escape := '[' '['
 
command := '[' ( command ( ':' sub-selector )* )? ( '@' style )? ']'
 
sub-selector := language | phrasing
 
// Switch the phrasing of the text.
// This will set the text-style matching the filter from the loaded style.
phrasing := phrasing-abbreviation | phrasing-bold | phrasing-code |
            phrasing-emphesis | phrasing-help | phrasing-italic |
            phrasing-key | phrasing-link | phrasing-math |
            phrasing-quote | phrasing-regular | phrasing-strong |
            phrasing-unarticulated
phrasing-abbreviation := 'a'
phrasing-bold := 'b'
phrasing-code := 'c'
phrasing-emphesis := 'e'
phrasing-help := 'h'
phrasing-italic := 'i'
phrasing-key := 'k'
phrasing-link := 'l'
phrasing-math := 'm'
phrasing-quote := 'q'
phrasing-regular := 'r'
phrasing-strong := 's'
phrasing-unarticulated := 'u'
 
// Switch the language of the text.
// This will set the text-style matching the filter from the loaded style.
language := 'L' <ietf-language-tag>
 
style := 'S' <style-name>
 
name := [^]]+
integer := [0-9]+
hex := [0-9a-zA-Z]
float := [0-9]* '.' [0-9]*

Examples

Switch for emphasis phrasing to regular phrasing.

foo[e]bar[r]baz

Read the "label" text-style, then switch to bold phrasing

foo[Rlabel;b]bar[r]baz

Select medium weight "Times New Roman" font, Select 12 pt, Set a mask for regular phrasing for all languages. Write the "test' text-style all current masks, then delete all masks.

[F5Times New Roman;S12Mr:*:*Wtest]foo