Re: Question about (excessive?) ram usage when many overlays (with large vscroll)

[dalanicolai]

I have a question about this, namely: how to make a line the 'window start'?

Using 'set-window-start` does not work.

From 'emacs -Q' (which starts within the scratch buffer),

immediately evaluate

(set-window-start nil (point))

to set the 'new' window start. Subsequently do

(set-window-vscroll nil 1)

it will scroll from the start of the buffer, and not from the 'new' window start

as I would expect

(of course, here there are no lines after the 'new' window start, but you could

insert 1 to 3 on separate lines then set the line with 1 to window start, but this

does not really change anything).

On Tue, 26 Apr 2022 at 14:49, Po Lu <luangruo@yahoo.com> wrote:

dalanicolai <dalanicolai@gmail.com> writes:

> So I have created `image-roll.el` for displaying documents/books (see
> here).  However, I have just noticed that it uses a large amount of
> RAM when viewing (or trying to) pages in the back of 'large'
> books. But even if RAM usage still looks perfectly fine, Emacs crashes
> when trying to scroll to higher page numbers.

I didn't try to reproduce this problem, but note that it's slow to
vscroll large amounts of text.  Instead, find the start of the first
line that will be visible onscreen (using window-text-pixel-size or
posn-at-point), make that the window start, and set vscroll starting
from there instead.