Re: The unwarranted scrolling assumption

[Lennart Borgman]

On Fri, Jun 18, 2010 at 3:52 PM, Eli Zaretskii <address@hidden> wrote:
>> From: Lennart Borgman <address@hidden>
>> Date: Fri, 18 Jun 2010 15:30:37 +0200
>> Cc: address@hidden
>>
>> >> It is !NILP (w->window_end_valid).
>> >
>> > ??? How can this be?  The code says:
>>
>> A misunderstanding, sorry. I meant that in this case that line/code
>> gave the value 0.
>>
>> >  if (b->clip_changed
>> >           && !NILP (w->window_end_valid)
>> >           && w->current_matrix->buffer == b
>> >           && w->current_matrix->zv == BUF_ZV (b)
>> >           && w->current_matrix->begv == BUF_BEGV (b))
>> >    b->clip_changed = 0;
>
> So what is the value of w->window_end_valid when you enter
> reconsider_clip_changes?  Is it nil?

This is the what I used to get the output I sent:

  if (b->clip_changed)
    DebPrint (("+++reconsider: end_valid=%d, b=%d, ZV=%d, BEGV=%d",
               !NILP (w->window_end_valid),
               w->current_matrix->buffer == b,
               w->current_matrix->zv == BUF_ZV (b),
               w->current_matrix->begv == BUF_BEGV (b)));



But I think you are on the wrong track here. Can we please leave this
until my patch has been investigated a bit more?

The problem is how clip_changed is handled by narrow_to_region etc.
That is what my patch is about.


>> So far there are two (mabye three) distinct bugs I have seen:
>>
>> 1) The handling of clip_changed, which I have sent a patch for.
>
> I explained in another message why I think your patch is wrong.
>
> The clip_changed flag should be reset to zero in order to enable the
> scrolling optimization.  This is done by reconsider_clip_changes.  So
> I think we should focus on understanding why it does not, in your
> case.


As I have said several times I think the problem is that clip_changed
is set by narrow_to_region etc. Please look into this first.


>> 2) The problems I described with visual-line-mode around line 702 in 
>> window.c.
>
> That's an entirely different problem.  Let's handle this one problem
> at a time.


Yes, let us not confuse them.