Re: preview-latex and display problem.

[Kim F. Storm]

David Kastrup <address@hidden> writes:

> In a different tack, I made a report several weeks ago concerning a
> duplicated image in proximity of the cursor and in the context of
> scrolling/non-scrolling that included screen shots (I think it was
> moderated away because of the screen shot attachments, but sent
> privately, too).
> 
> The reported problem is still apparent.  I am using a 10x20 startup
> font and 80x34 geometry if this helps reproducing the problem.


I can reproduce this, and I know the cause -- I just don't know
how to fix it easily.

The problem is that a fairly small image is shown instead of approx 40
lines of original text.  However, to scroll the window, emacs goes
(in your case) approx 20 lines backwards in the buffer -- which means
that it ends up in the middle of the text that is displayed as the image;
this means that redisplay is confused as to what buffer position
corresponds to the start of the window, and does strange things when 
it uses that (in the middle of nowhere) position as the basis for
scrolling in the window.

Generally, I think the current "move backwards in buffer" function in
emacs is severely flawed as it is based on "even line height"
calculation which doesn't fit well with variable line height and
invisible/replaced text.

I'll find a way to fix this...

-- 
Kim F. Storm  http://www.cua.dk