[schwab@suse.de: Display bug with miscomputed window-start]

[schwab@suse.de: Display bug with miscomputed window-start]

[Richard Stallman]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 1789 bytes --]

Since this is in redisplay, could you look at it?

------- Start of forwarded message -------
Envelope-to: rms@gnu.org
Delivery-date: Mon, 28 Oct 2002 11:54:08 -0500
X-Authentication-Warning: sykes.suse.de: schwab set sender to schwab@suse.de using -f
To: emacs-devel@gnu.org
Subject: Display bug with miscomputed window-start
X-Yow: I don't think you fellows would do so much RAPING and PILLAGING if
 you
 played more PINBALL and watched CABLE TELEVISION!!
From: Andreas Schwab <schwab@suse.de>
Sender: emacs-devel-admin@gnu.org
Date: Mon, 28 Oct 2002 17:48:49 +0100

Redisplay does not correctly handle characters that wrap around at the
right margin.  To reproduce:

- - Insert a bunch of ^A (C-q C-a) in a buffer so that the line wraps around
- - Go to point-min
- - If there is an even number of columns insert a space, so that the last
  ^A in the line wraps around, i.e the ^ is in the last column and the A
  appears at the start of the next screen line.
- - Do M-1 C-v (scroll-up 1)

The cursor will now be somewhere in the middle of the window, maybe not
even inside any buffer text.  Now click on first visible ^A to move point
there and evaluate (list (point) (window-start)).  You will get two
different numbers that are off by one (`(42 41)' for an 80 column
display).

Note that if you change the character that wraps around to a TAB this bug
does not occur.

Andreas.

- -- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."


_______________________________________________
Emacs-devel mailing list
Emacs-devel@gnu.org
http://mail.gnu.org/mailman/listinfo/emacs-devel
------- End of forwarded message -------

Re: [schwab@suse.de: Display bug with miscomputed window-start]

[Ein Terakawa]

> Redisplay does not correctly handle characters that wrap around at the
> right margin.

Almost half a year ago I posted a patch to fix this and related probrems.
I agreed with you on my doing translation of the explanation.
But I'm afraid I haven't finished it yet.

Here is the partly done explanation.
http://applause.elfmimi.jp/emacs-lisp/emacs-21.1-proper-continuation-20020518-en.txt

And the patch for the latest cvs version.
http://applause.elfmimi.jp/emacs-lisp/emacs-21.3.50-proper-continuation-20021029.diff.gz

----
Ein Terakawa <applause@elfmimi.jp>