Re: longlines.el problems...

[Chong Yidong]

> I just tried out longlines-mode with AUCTeX/preview-latex.  Cough,
> cough.  One problem that it has is that it does not preserve markers
> around spaces/newlines.
>
> Here is how to do this in one case (unless I am mistaken):
> But it looks like quite a number of other passages might need similar
> fixes.

There is only one place where spaces and newlines are converted into one
another; that is the function longlines-wrap-line. So you missed only one
spot.  The following patch follows through on your suggested changes.  It
is correct as far as longlines is concerned; could you check if it does
the right thing for AUCTeX/preview-latex?

I didn't test longlines with AUCTeX/preview-latex, because I don't have
those installed.  So chances are there'll be incompatibilities :-/

> Another thing worth mentioning is that in the presence of images, font
> locking with different font sizes, proportional fonts and similar, the
> wrapped column should certainly be the visual column instead of
> anything else.  This means, for example, that it is completely useless
> to insert a newline in the middle of an image: it only makes sense to
> replace such spaces that have a different visual column.
> Unfortunately, current-column does not take images into account.

Sure, it would be nice, but (from what I remember) it's a pretty
complicated problem.  So longlines simply uses the value of fill-column. 
This is simple, plays nicely with fill-paragraph, and works just fine 99%
of the time.

If your fancy fonts make the fill-paragraph column fall short of the
screen width, it's generally not too ugly; things only start getting weird
if your fancy fonts make the fill-paragraph column extend past the screen
width.  But it'll be weird whether or not longlines is active.


*** emacs/lisp/longlines.el~    Wed Jul 13 00:05:40 2005
--- emacs/lisp/longlines.el     Wed Jul 13 00:48:19 2005
***************
*** 207,229 ****
  If wrapping is performed, point remains on the line.  If the line does
  not need to be wrapped, move point to the next line and return t."
    (if (longlines-set-breakpoint)
!       (progn (backward-char 1)
!              (delete-char 1)
!              (insert-char ?\n 1)
               nil)
      (if (longlines-merge-lines-p)
          (progn (end-of-line)
!                (delete-char 1)
       ;; After certain commands (e.g. kill-line), there may be two
       ;; successive soft newlines in the buffer.  In this case, we
       ;; replace these two newlines by a single space.  Unfortunately,
       ;; this breaks the conservation of (spaces + newlines), so we
       ;; have to fiddle with longlines-wrap-point.
!                (if (or (bolp) (eolp))
!                    (if (> longlines-wrap-point (point))
!                        (setq longlines-wrap-point
!                              (1- longlines-wrap-point)))
!                  (insert-char ?  1))
                 nil)
        (forward-line 1)
        t)))
--- 207,234 ----
  If wrapping is performed, point remains on the line.  If the line does
  not need to be wrapped, move point to the next line and return t."
    (if (longlines-set-breakpoint)
!       (progn (insert-before-markers "\n")
!              (backward-char 1)
!              (delete-char -1)
!              (forward-char 1)
               nil)
      (if (longlines-merge-lines-p)
          (progn (end-of-line)
!                (forward-char 1)
       ;; After certain commands (e.g. kill-line), there may be two
       ;; successive soft newlines in the buffer.  In this case, we
       ;; replace these two newlines by a single space.  Unfortunately,
       ;; this breaks the conservation of (spaces + newlines), so we
       ;; have to fiddle with longlines-wrap-point.
!                (if (eq (char-after) ?\n)
!                    (progn (if (> longlines-wrap-point (point))
!                             (setq longlines-wrap-point
!                                   (1- longlines-wrap-point)))
!                         (delete-char -1))
!                  (insert-before-markers " ")
!                (backward-char 1)
!                (delete-char -1)
!                (forward-char 1))
                 nil)
        (forward-line 1)
        t)))