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- English is the default language and hence default direction is LTR.
- Urdu is the only language (In in Scope) which is RTL in direction.
- A page may contain multiple languages content. Eg - A student may see English and any Indian language learning content as a part of their curriculum.
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Core concepts
Adding attribute dir="rtl" reverses the directionality of the element.
- Adding attribute lang="**" is useful for the browser, Search engines and Web accessibility tools.
From the performance perspective, all languages fonts should not be downloaded by default. A font file should be downloaded based on the need basis. Better explanation - https://ui-demo.github.io/fonts2.html
Implementation Details
HTML Side changes
Based on the user opted language for the interface, HTML tag must contain lang and dir attribute. If the user has not opted any language, English will be the default. Eg - <html lang="en-GB" dir="ltr">.
- Based on the content a content element loads, the content element should have lang and dir attributes. Eg - If a card contains the Urdu content - <app-card lang="ur" dir="rtl">
CSS Side Changes
- All language and directional CSS will be served from the single CSS file. i.e. style.css. No Separation of CSS files based on directionality or Language. Performance related concerns/challenges can be handled in effective ways.
- Directional Challenges (Avoiding duplicate codes)
- Some properties which break the inherited directionality of element should be avoided as much as possible such as - text-align, float, left and right properties etc. Eg - an element with CSS property text-align: left will not change directionality to right on changing HTML dir="rtl" hence should be avoided.
- Directionality breaking CSS properties should be replaced with the reusable classes. Eg - mr-20 will add margin-right: 20px in ltr but in rtl it will add margin-left: 20px. Directional properties will be nested with the directional attribute so as to isolate them. Eg- *[dir=ltr] .mr-20{margin-right:20px;} and *[dir=rtl] .mr-20{margin-left:20px;}.
- Multi-font Challenges (Avoid downloading font files if language not used on the page)
- Language special CSS will be written with nesting to language attribute selector selector rather than assigning it to the body tag. Eg - *[lang=ur] {font-family: "Noto Nastaliq Urdu";}
- More details on - https://ui-demo.github.io/fonts2.html
Some Useful links -
- https://w3c.github.io/i18n-tests/results/native-user-interfaces
- https://www.w3.org/International/questions/qa-html-dir#ie
https://www.w3.org/TR/html4/struct/dirlang.html
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