HTML Ruby and Bidirectional Text

The set of HTML <ruby> elements allow us to add pronunciation above text. For example:

"When you visit the zoo, be sure to see the panda - 熊(Xióng)猫(māo)."

This is written as:

<ruby>熊<rp>(</rp><rt>Xióng</rt><rp>)</rp></ruby><ruby>猫<rp>(</rp><rt>māo</rt><rp>)</rp></ruby>.

That is, the word or character which needs text above it is wrapped in <ruby>. The pronunciation is wrapped in <rt>. The <rp> element indicates the presence of a parenthesis - which isn't usually displayed, but will be shown if the browser doesn't support <ruby> syntax.

That's fairly easy for scripts written left-to-right. But how does it work for scripts like Arabic where the text is written right-to-left, but the user may want the pronunciations left-to-right?

Let's take the phrase "Hello World" in Arabic: مرحبا بالعالم. Google Translate tells me this is pronounced "marhaban bialealami".

For a single word, the directionality can be ignored. The browser should be smart enough to place the pronunciation above the word:

<p>Hello is: <ruby>مرحبا<rp>(</rp><rt>marhaban</rt><rp>)</rp></ruby>. What a useful word!</p>

Hello is: مرحبا(marhaban). What a useful word!

What about if we have a few words - or a whole sentence - which is entirely RTL?

<p dir="rtl">مرحبا بالعالم</p>

Is displayed aligned to the right side of the screen:

مرحبا بالعالم

There are a few ways to add pronunciation.

Separate The Words

The first is to write each word separately. For example <ruby>1st word</ruby> <ruby>2nd word</ruby>. Obviously, this isn't normally how you'd write a RTL language! But it does work:

<p dir="rtl"><ruby>مرحبا<rp>(</rp><rt>marhaban</rt><rp>)</rp></ruby> <ruby>بالعالم<rp>(</rp><rt>bialealami</rt><rp>)</rp></ruby></p>

Which displays as:

مرحبا(marhaban) بالعالم(bialealami)

It helps to think of the way the characters of the script are stored in memory.

A word that displays as ABC is stored as C B A.

So the above is written "correctly" - even though it looks odd in the source-code view.

All At Once

But there is an alternative if you want the source text to look natural - i.e. [2nd word] [1st word].

It's a bit messy, but you can write the LTR text in <rt> "backwards"!

<p dir="rtl"><ruby>مرحبا بالعالم<rt>bialealami marhaban</rt></ruby></p>

مرحبا بالعالمbialealami marhaban

But, again, that doesn't seem very satisfying! It also divorces the pronunciation from the original word - which is unfortunate for screenreaders.

The Ruby layout algorithm is usually clever enough to group words separated by spaces:

مرحبا بالعالمB A

مرحبا بالعالمBbbbbbbbbbbbbb Aaaaaaaaaaaaa

Although, if the pronunciations have a significantly different length than each other, it can get a bit messy:

مرحبا بالعالمBbbbbbbbbbbbbb A

مرحبا بالعالمB Aaaaaaaaaaaaa

In which case, you probably need to go for the first technique and wrap each word in its own <ruby> element:

مرحبا(A) بالعالم(Bbbbbbbbbbbbbb)

BDO

It's tempting to think that simply using the <bdo> element can help us here. It can't!

Using the bidirectional override will display characters RTL, rather than words.

<p dir="rtl"><ruby>مرحبا بالعالم<rt><bdo dir="rtl">marhaban bialealami</bdo></rt></ruby></p>

Becomes:

مرحبا بالعالمmarhaban bialealami

I guess you could spell each word backwards. Which would be extremely annoying for everyone and a complete nightmare for screen readers!

Instead, it can be fixed if each word is then given an explicit LTR direction:

<p dir="rtl"><ruby>مرحبا بالعالم<rt>
   <bdo dir="rtl">
      <span dir="ltr">marhaban</span> <span dir="ltr">bialealami</span>
   </bdo></rt></ruby></p>

مرحبا بالعالم

marhaban bialealami

Is that it?

So, I think those are the only ways to achieving mixing bidirectional text pronunciation. But I'd welcome any corrections and suggestions!