[dak@gnu.org: Strange scrolling with partially visible lines.]

[dak@gnu.org: Strange scrolling with partially visible lines.]

[Richard Stallman]

Could someone please DTRT with this, and ack?

------- Start of forwarded message -------
To: emacs-devel@gnu.org
From: David Kastrup <dak@gnu.org>
Date: Thu, 01 Jun 2006 22:30:49 +0200
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Subject: Strange scrolling with partially visible lines.
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If I have a mail with an embedded image at the bottom (which runs off
the frame), and I try walking over it with forward-char, instead of
the cursor being displayed on the image itself (when it reaches
there), the cursor blinks at the top left corner of the window (where
it has no business whatsoever).  When doing another forward-char,
scrolling commences to after the image.

This is with a version from today.  I don't know for sure how long
this weird behavior has been there already, but a month ago or so
things were still behaving reasonably.

There are also several cases now in a buffer with multiple large
images where repeated scroll-up gets stuck in a loop because one of
the scroll-up commands makes backward progress.

- -- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum


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Re: [dak@gnu.org: Strange scrolling with partially visible lines.]

[David Kastrup]

Richard Stallman <rms@gnu.org> writes:

> Could someone please DTRT with this, and ack?
>
> From: David Kastrup <dak@gnu.org>
> Subject: Strange scrolling with partially visible lines.
> To: emacs-devel@gnu.org
> Date: Thu, 01 Jun 2006 22:30:49 +0200
>
>
> If I have a mail with an embedded image at the bottom (which runs off
> the frame), and I try walking over it with forward-char, instead of
> the cursor being displayed on the image itself (when it reaches
> there), the cursor blinks at the top left corner of the window (where
> it has no business whatsoever).  When doing another forward-char,
> scrolling commences to after the image.

Kim did some changes after that, and I could not reproduce the effect.
Last time I looked, there were still scrolling peculiarities
remaining.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum

Re: [dak@gnu.org: Strange scrolling with partially visible lines.]

[Kim F. Storm]

David Kastrup <dak@gnu.org> writes:

>> If I have a mail with an embedded image at the bottom (which runs off
>> the frame), and I try walking over it with forward-char, instead of
>> the cursor being displayed on the image itself (when it reaches
>> there), the cursor blinks at the top left corner of the window (where
>> it has no business whatsoever).  When doing another forward-char,
>> scrolling commences to after the image.
>
> Kim did some changes after that, and I could not reproduce the effect.
> Last time I looked, there were still scrolling peculiarities
> remaining.

I have looked at those problems, and I have some ideas how to fix
them, but IIRC, we agreed back when I made the changes to make images
scrollable (using vscroll) that we needed to rework thiscompletely
after the release.

In any case, if I find a _simple_ way to improve the current code,
I'll install it.

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

Re: [dak@gnu.org: Strange scrolling with partially visible lines.]

[Kim F. Storm]

storm@cua.dk (Kim F. Storm) writes:

> David Kastrup <dak@gnu.org> writes:
>
>>> If I have a mail with an embedded image at the bottom (which runs off
>>> the frame), and I try walking over it with forward-char, instead of
>>> the cursor being displayed on the image itself (when it reaches
>>> there), the cursor blinks at the top left corner of the window (where
>>> it has no business whatsoever).  When doing another forward-char,
>>> scrolling commences to after the image.
>>
>> Kim did some changes after that, and I could not reproduce the effect.
>> Last time I looked, there were still scrolling peculiarities
>> remaining.
>
> I have looked at those problems, and I have some ideas how to fix
> them, but IIRC, we agreed back when I made the changes to make images
> scrollable (using vscroll) that we needed to rework thiscompletely
> after the release.
>
> In any case, if I find a _simple_ way to improve the current code,
> I'll install it.

I have looked some more at this problem, and one basic flaw that need
to be fixed is that to scroll through a partially visible image,
we currently always adjusts the vscroll (and keep the window-start)
also in cases where there is text above the image, so that adjusting
window start makes more sense.

This is not the only flaw though, so I'll keep looking at it...


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

Re: [dak@gnu.org: Strange scrolling with partially visible lines.]

[David Kastrup]

storm@cua.dk (Kim F. Storm) writes:

> storm@cua.dk (Kim F. Storm) writes:
>
>> David Kastrup <dak@gnu.org> writes:
>>
>>> Last time I looked, there were still scrolling peculiarities
>>> remaining.
>
> I have looked some more at this problem, and one basic flaw that need
> to be fixed is that to scroll through a partially visible image,
> we currently always adjusts the vscroll (and keep the window-start)
> also in cases where there is text above the image, so that adjusting
> window start makes more sense.
>
> This is not the only flaw though, so I'll keep looking at it...

At the moment I am not trying to reproduce anything in particular
(usually taking the example file of preview-latex, running it through
preview-document and paging back and forth is still giving enough
trouble as to not require looking for it) because we are supposed to
go into pretest tomorrow and I am still trying to wrap my head around
making key-binding follow events.  That's pretty urgent, since while
it will fix a few bugs, it is somewhat feature-flavored.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum

Re: [dak@gnu.org: Strange scrolling with partially visible lines.]

[Kim F. Storm]

David Kastrup <dak@gnu.org> writes:

> storm@cua.dk (Kim F. Storm) writes:
>
>> storm@cua.dk (Kim F. Storm) writes:
>>
>>> David Kastrup <dak@gnu.org> writes:
>>>
>>>> Last time I looked, there were still scrolling peculiarities
>>>> remaining.
>>
>> I have looked some more at this problem, and one basic flaw that need
>> to be fixed is that to scroll through a partially visible image,
>> we currently always adjusts the vscroll (and keep the window-start)
>> also in cases where there is text above the image, so that adjusting
>> window start makes more sense.
>>
>> This is not the only flaw though, so I'll keep looking at it...
>
> At the moment I am not trying to reproduce anything in particular
> (usually taking the example file of preview-latex, running it through
> preview-document and paging back and forth is still giving enough
> trouble as to not require looking for it) because we are supposed to
> go into pretest tomorrow and I am still trying to wrap my head around
> making key-binding follow events.  That's pretty urgent, since while
> it will fix a few bugs, it is somewhat feature-flavored.

I still have the sample you sent me a while back.

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

Re: [dak@gnu.org: Strange scrolling with partially visible lines.]

[Kim F. Storm]

storm@cua.dk (Kim F. Storm) writes:

> I have looked some more at this problem, and one basic flaw that need
> to be fixed is that to scroll through a partially visible image,
> we currently always adjusts the vscroll (and keep the window-start)
> also in cases where there is text above the image, so that adjusting
> window start makes more sense.
>
> This is not the only flaw though, so I'll keep looking at it...

I have just installed some changes to line-move and scrolling which
should make scrolling of partially visible lines _better_.

It is still not perfect -- particularly in Gnus article buffers, it
doesn't behave quite well with very wide images, probably due to the
way Gnus inserts the image in the buffer [using overlays or some such
on a newline].

But the random forward/backward jumping doesn't seem to happen anymore
-- at least not for normal images.

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

Re: [dak@gnu.org: Strange scrolling with partially visible lines.]

[Richard Stallman]

    But the random forward/backward jumping doesn't seem to happen anymore
    -- at least not for normal images.

Thanks for working on this.