bug#2541: 23.0.91; doc-view: unexpected scrolling after returning to text mode

bug#2541: 23.0.91; doc-view: unexpected scrolling after returning to text mode

[Markus Triska]

Given p.ps from:

   http://www.logic.at/prolog/p.ps

when I do:

1)   $ emacs -Q p.ps

2)   M-: (setq doc-view-ghostscript-options (list "-dSAFER" "-dNOPAUSE" "-sDEVICE=png16m" "-dTextAlphaBits=4" "-dBATCH" "-dGraphicsAlphaBits=4" "-dQUIET" "-dEPSCrop")) RET

3)   C-u - 1 M-r C-c C-c C-v C-c C-c

then (as expected) doc-view returns to text mode, and point is on the
same position where it was before entering graphics mode. When I then
press C-p repeatedly, instead of moving point to the previous line,
the text is unexpectedly scrolled down without moving point.

In GNU Emacs 23.0.91.1 (i386-apple-darwin8.11.1, GTK+ Version 2.12.9)
 of 2009-03-01 on mt-computer.local
Windowing system distributor `The XFree86 Project, Inc', version 11.0.40400000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

bug#2541: 23.0.91; doc-view: unexpected scrolling after returning to text mode

[Tassilo Horn]

Markus Triska <markus.triska@gmx.at> writes:

> Given p.ps from:
>
>    http://www.logic.at/prolog/p.ps
>
> when I do:
>
> 1)   $ emacs -Q p.ps
>
> 2)   M-: (setq doc-view-ghostscript-options (list "-dSAFER" "-dNOPAUSE" "-sDEVICE=png16m" "-dTextAlphaBits=4" "-dBATCH" "-dGraphicsAlphaBits=4" "-dQUIET" "-dEPSCrop")) RET
>
> 3)   C-u - 1 M-r C-c C-c C-v C-c C-c
>
> then (as expected) doc-view returns to text mode, and point is on the
> same position where it was before entering graphics mode. When I then
> press C-p repeatedly, instead of moving point to the previous line,
> the text is unexpectedly scrolled down without moving point.

I can reproduce that (even without step 2) using

  GNU Emacs 24.0.50.1 (x86_64-pc-linux-gnu) of 2011-01-11 on thinkpad

However, C-p is bound to `previous-line' as usual in that context.

After edebugging a bit, I found that the reasion is that in

--8<---------------cut here---------------start------------->8---
(defun line-move (arg &optional noerror to-end try-vscroll)
  (unless (and auto-window-vscroll try-vscroll
	       ;; Only vscroll for single line moves
	       (= (abs arg) 1)
	       ;; But don't vscroll in a keyboard macro.
	       (not defining-kbd-macro)
	       (not executing-kbd-macro)
	       (line-move-partial arg noerror to-end))
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    (set-window-vscroll nil 0 t)
    (if line-move-visual
	(line-move-visual arg noerror)
      (line-move-1 arg noerror to-end))))
--8<---------------cut here---------------end--------------->8---

the underlined call scrolls one line and returns some integer in that
context.  That makes the and clause return non-nil, and so the unless
body is not executed.  I don't know this part of emacs, so I don't know
how to fix the issue...

But I don't think that has something to do with doc-view.

Bye,
Tassilo

bug#2541: 23.0.91; doc-view: unexpected scrolling after returning to text mode

[Lars Ingebrigtsen]

Markus Triska <markus.triska@gmx.at> writes:

> Given p.ps from:
>
>    http://www.logic.at/prolog/p.ps
>
> when I do:
>
> 1)   $ emacs -Q p.ps
>
> 2)   M-: (setq doc-view-ghostscript-options (list "-dSAFER" "-dNOPAUSE" "-sDEVICE=png16m" "-dTextAlphaBits=4" "-dBATCH" "-dGraphicsAlphaBits=4" "-dQUIET" "-dEPSCrop")) RET
>
> 3)   C-u - 1 M-r C-c C-c C-v C-c C-c
>
> then (as expected) doc-view returns to text mode, and point is on the
> same position where it was before entering graphics mode. When I then
> press C-p repeatedly, instead of moving point to the previous line,
> the text is unexpectedly scrolled down without moving point.

I tried this in Emacs 27, but was unable to reproduce the error -- `C-p'
moves around as usual, as far as I can tell.

Are you still seeing this problem in modern versions of Emacs?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#2541: 23.0.91; doc-view: unexpected scrolling after returning to text mode

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Are you still seeing this problem in modern versions of Emacs?

More information was requested some weeks back, but no response was
given, so I'm closing this bug report.  Please reopen if this is still
an issue.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no