Re: Unicode surrogates in browsers for the compelling demo

From: Peter_Constable@sil.org
Date: Mon Nov 19 2001 - 14:41:55 EST


On 11/18/2001 10:23:47 PM James Kass wrote:

>If a Plane Two character can flicker on-and-off in MSIE 5.5
>on Win M.E., then this OS and browser should be able to
>display non-BMP text without any problem.

I'm surprised that plane 2 characters can show up at all on WinMe. This
isn't an IE or Uniscribe issue, it'd a GDI issue: something has to do the
cmap lookup, and that something has to be able to handle the newer cmap
formats that support surrogates. I was under the impression that this
first appeared on Win2K. Which leads me to be sceptical and wonder how you
know that those are plane 2 characters if they only appear as momentarily
flickers?

>I don't expect it to work in Notepad on M.E., but I do expect
>it to work in MSIE. M.E. isn't Unicode based, but MSIE and
>Uniscribe handle complex script OpenType substitutions
>well. The level of sophistication required for such complex
>script handling is much, much greater than that of parsing
>a slightly modified character map format in a font.

That's true, but the parsing of that cmap format must still be done, and
as far as I know it's handled by GDI. I could be wrong, though.

>Since MSIE and Uniscribe are already correctly parsing that
>new character map format (else, how could the correct
>Plane Two character appear at all?),

Since I have been under the impression that IE and Uniscribe do *not* deal
with parsing cmaps, I am doubting that anybody has actually seen plane 2
characters on WinMe.

>It also
>illustrates that non-BMP support is still rather new, still
>under testing, and still being developed.

No debate there.

- Peter

---------------------------------------------------------------------------
Peter Constable

Non-Roman Script Initiative, SIL International
7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA
Tel: +1 972 708 7485
E-mail: <peter_constable@sil.org>



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