Re: Parital scrolling of image

[David Kastrup]

address@hidden (Kim F. Storm) writes:

> David Kastrup <address@hidden> writes:
>
>>>> 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.
>>
>> I can.  Generate previews, then walk with cursor left-right into a
>> preview that starts in the first column
>> (\begin{equation}...\end{equation} is a good candidate).  Then walk a
>> few cursor positions to the right, then cursor up.  The cursor will
>> just stick.  See bottom half of included screen shot for a scenario.
>
> Does this still happen with my latest fixes?

Oh, you fixed it pretty soon, and I just checked that the behavior is
still fixed.

>> Then there is another one: if you have a small window with a
>> partial graphic at the bottom, and you use scroll-down, then the
>> partial graphic gets moved down pretty much as expected, only to
>> scroll up back on-screen when the cursor blinks.  That is: in some
>> instances the scrolling decisions do not survive cursor blinking.
>
> I think I have fixed this.  Please test.

I've not seen the effect right now.  One thing that is apparent when
playing with scroll-down and scroll-up is that scroll-down tends to
jump to the start of an overtall image in one go, whereas using
scroll-up will go through an image in nice chunks.  I have also had a
few intermittent cases where scroll-up signaled "End of buffer" when
the buffer was not yet at the end.  I have not seen any crashes in the
current version though, and I'd hate to sacrifice _that_.

> I also fixed it so that when you move backwards into an image, emacs
> now shows that bottom part of the image, rather than the top part
> (which triggers the crash in sit-for).

Uh, yes?  Oh, I see: that is for previous-line.  Yup, works.  What I
just reported was for scroll-down in contrast.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum