Re: Parital scrolling of image

[storm@cua.dk (Kim F. Storm)]

David Kastrup <dak@gnu.org> writes:

> This looks much better.  But here are some remarks:
>
> a) an "open preview" that starts on a line of its own in preview-latex
> has an overlay starting at the beginning of the line.  This overlay
> has a before-string consisting of an image (display-property on a
> single x character IIRC) followed by \n (so that the image will appear
> on a line of its own).  Note that the image as well as the \n are not
> connected to a character in the buffer, but appear just as
> before-string.  Nevertheless, previous-line in the first _real_ line
> of the overlay will be sufficiently confused as to not move at all.
> Never.  This effect is probably not related to the very latest
> changes, though.  I just noticed it when playing with the new code.
> It leads to pretty unintuitive results, though.

I tried various things with your circ.tex, but I cannot reproduce this
with my latest fixes.  Please test again -- and if you can still
reproduce it, pls. tell me how (and what is unintuitive about the
results you see).

>
> b) Making a window as small as possible (2 lines or so) means that
> scroll-down and scroll-up, that are supposed to scroll by a "near full
> screen", namely `next-screen-context-lines' less than a full screen,
> scroll, if at all, in the opposite direction than expected.  In case
> that the `next-screen-context-lines' less than a full screen delivers
> a negative or zero value, 1 should rather be substituted.

I fixed this for pixel-based scrolling.  

I have also fixed a redisplay loop where resizing the frame that
displays your circ.tex with graphics loops trying to make the cursor
line fully visible.

>
> This should be a general paradigm: all window-based movement/scrolling
> commands should make _some_ progress, and in the _expected_ direction.

True.

>
> c) when pressing next-line, an image will get scrolled in smaller
> chunks (by the way, maybe one should be able to configure the size of
> those chunks).  That is nice.  previous-line shows no such behavior,
> however: it scrolls an image with one big jump.  A bit of symmetry
> here would probably be nice to have.

Inside the image, previous-line does scroll backwards.

It is true that if you use previous-line to move into a tall image
you get to the first part of that image rather than the last part
as you would expect.   I will see what I can do about it.

>
> That being said, the behavior we now have for next-line is much much
> better than what was available at any previous time.

I think so too.

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk