GNU bug report logs - #29837
UTF-16 char display problems and the macOS "character palette"

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From: Alan Third <alan <at> idiocy.org>
To: Philipp Stephani <p.stephani2 <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 29837 <at> debbugs.gnu.org
Subject: bug#29837: UTF-16 char display problems and the macOS "character palette"
Date: Tue, 26 Dec 2017 01:34:23 +0000

On Mon, Dec 25, 2017 at 08:13:55PM +0000, Philipp Stephani wrote:
> IIUC Emacs receives the input as a single UTF-16 string (in
> insertText), then iterates over the UTF-16 code units, converting
> each into an Emacs event. That's wrong, no matter whether the input
> comes from the character palette or from the keyboard; normal
> keyboard layouts just happen to not contain non-BMP characters. The
> loop needs to account for surrogates.

I finally came to this conclusion myself. I now know a lot more about
UTF‐16 than I did yesterday. :)

Wish I’d looked at my email earlier, though.

> As a small optimization (which is warranted because the function is
> probably called on every keystroke), this should use [NSString
> getCharacters:range:] to copy all the UTF-16 code units to a buffer
> first, to avoid repeated calls to characterAtIndex.

Presumably the vast majority of input will consist of just one code
unit, though?
-- 
Alan Third

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