Re: fo:character and zero width space

On Thu, Feb 11, 2016 at 9:23 PM, Carlos Villegas <[email protected]> wrote:

> I'm trying to use FOP 2.0 to render Thai language. FOP doesn't really
> support Thai script


FOP does support Thai, at least glyph composition, though there appears to
be a few open issues (FOP-2092
<https://issues.apache.org/jira/browse/FOP-2092>, FOP-2355
<https://issues.apache.org/jira/browse/FOP-2355>). It is also true that FOP
is not presently performing line breaking in phrase internal positions (
FOP-2066 <https://issues.apache.org/jira/browse/FOP-2266>), which proposes
a solution to employ ICU and use dictionary based LB.


> , so I'm using an external program (libthai) to do glyph composition and
> word breaking.
> Thai doesn't use spaces to separate words, so I was just inserting zero
> width spaces to separate words. This works fine.
> However, for justified text, these zero width spaces don't stretch, so
> nothing happens, I get no justified text.
> So, I tried to use fo:character with character set to zero width space,
> and setting the letter-spacing.maximum to allow some stretching.
>

Zero width space (U+200B) is not treated as a word separator space by
default. Have you tried something like:

<fo:character treat-as-word-space='true'>&#x200B</fo:character>

If that doesn't work, then keep in mind that letter spacing has no meaning
when applied to a single character, but applies to a sequence of
characters. Accordingly, I would try something like:

<fo:inline letter-spacing.minimum="0em"
letter-spacing.maximum="0.1em">&#x200B;&#x200B;</fo:inline>

or

<fo:inline letter-spacing.minimum="0em"
letter-spacing.maximum="0.1em">&#x200B;<fo:character
treat-as-word-space='true'>&#x200B;</fo:character></fo:inline>

If neither approach works, it may require some time with a visual debugger,
e.g., Eclipse, to step through the code and find out where things go wrong.



> But now FOP doesn't seem to treat the zero width space as such this way,
> it doesn't break anymore at all!
>
> Note that Thai does make use of regular spaces to separate sentences and
> for other purposes but there's no guarantee that you have spaces in a given
> paragraph or in case of long sentences.
>
> Is there a way to insert a breakable space with minimum and optimum to
> zero width and some small value for maximum?
>
> Carlos
>
>
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