Re: Ncursesw bug in refreshing wide character (with patch)

[Thomas Dickey]

On Sun, 5 Dec 2004, Eungkyu Song wrote:

> Hi,
>
> In the case that there are wide characters and characters in next line
> (or previous line), when is scroll screen some wide characters are
> broken.
>
> This is happen because ncurses does not handle nac character correctly.

hmm - I rewrote that in the 20041023 patch:

20041023
        + add logic in waddch_literal() to clear orphaned cells when one
          multi-column character partly overwrites another.
        + improved logic for clearing cells when a multi-column character
          must be wrapped to a new line.
        + revise storage of cells for multi-column characters to correct a
          problem with repainting.  In the old scheme, it was possible for
          doupdate() to decide that only part of a multi-column character
          should be repainted since the filler cells stored only an attribute
          to denote them as fillers, rather than the character value and the
          attribute.

So "isnac()" is no more.

But your comment reminds me of a related issue with scrolling: the 
WINDOW_EXT member addch_y is not updated during scrolling - which would be 
important if one scrolls the screen in the middle of adding a multibyte 
character.  From the context I can't tell if your patch deals with a 
different slice of that.

It's a relatively simple fix, so I should be able to add that in the next 
patch - and though the changes for the form-library aren't complete, a 
rollup patch is past due. (Unless some more serious problem arises, I'll
do that next week).

> You can replay it like this
>
> you need UTF-8 or EUC-KR enabled terminal or font.
> LANG=ko_KR mutt and scroll the help screen.
> (ja_JP will be ok, too)
>
> I attached patch.
>
> ps) plz cc me
>
> --
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--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net