On Sat, Jul 02, 2005 at 03:49:01PM -0400, Daniel Burrows wrote: > Package: libncursesw5 > Version: 5.4-8 > Severity: normal > > I've just finished converting aptitude's display routines to understand > about >8-bit character set locales such as utf8. Everything works fine in > typical European locales -- however, when I tried setting the locale to > zh_CN, I noticed some display artifacts. After a bit of experimentation, I > believe that I've found the general situation that's causing this problem. > As you probably know, Chinese characters are "wide" -- by which I mean that > they take two columns on the text terminal. The problem I'm encountering > occurs when a wide character is *partially* overlapped by a non-wide > character. For instance, you can see this when a popup menu appears on top > of a background of wide-character text:
I can see where the problem is, will make a fix in the next patch.
Other than the usual distractions, it took a few hours debugging due
to the large size of the trace when running aptitude (to see how to
get the information I needed). It seems that aptitude creates a _lot_
of windows (my first cut of a trace got 300Mb of trace). aptitude
would probably run faster if it didn't do that.
Anyway, the problem is that for the special case I'm seeing,
ncurses/tty/tty_update.c is doing the wrong thing when there's
an overlapped character. This is the chunk that's wrong (around
line 1300):
if (oLastChar < nLastChar) {
int m = max(nLastNonblank, oLastNonblank);
GoTo(lineno, n + 1);
if (
#if USE_WIDEC_SUPPORT
isWidecExt(newLine[n + 1]) ||
#endif
InsCharCost(nLastChar - oLastChar) > (m - n)) {
PutRange(oldLine, newLine, lineno, n + 1, m);
} else {
InsStr(&newLine[n + 1], nLastChar - oLastChar);
}
The isWidecExt() ifdef is new since 5.4, and for this particular case is
applied too late to work properly. Also if the InsStr() branch is taken,
I see the menu border overwritten. So there are two problems in that
chunk.
(I have a preliminary fix, but it was late at night -have to review ;-)
--
Thomas E. Dickey <[EMAIL PROTECTED]>
http://invisible-island.net
ftp://invisible-island.net
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