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bug#29002: it.first_visible_x is erroneously 0 while horizontal scrollin
From: |
Keith David Bershatsky |
Subject: |
bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling. |
Date: |
Sun, 29 Oct 2017 11:56:22 -0700 |
I agree ... and that leads us to bug #29002. :)
In the normal situation, the screen refreshes when the arrow key is used and
non-current lines cease to be horizontally scrolled. In the current example,
however, non-current lines remain horizontally scrolled and Emacs "thinks" that
they are not. When I say that Emacs "thinks" they are not, I am referring to
IT.
There are few ways that I look at this unique situation:
A. If the Emacs design is to permit non-current lines to remain horizontally
scrolled in this unique situation, then we may need something like a new window
pointer to store the value of the first-visible-x for those non-current lines.
OR
B. If the Emacs design is NOT to permit non-current lines to remain
horizontally scrolled in this unique situation, then redisplay needs to refresh
all non-current lines so that they snap back to a non-horizontal scroll state.
OR
C. IT is incorrect such that it.first_visible_x needs to be changed to reflect
the proper value. [From an untrained eye, it looks like the value is the same
as w->hscroll in this unique situation.]
If this unique situation is "a feature", then we need a way to properly
calculate the first-visible-x for non-current lines. If this is *not* a
feature, then redisplay should refresh all non-current lines so that they are
no longer horizontally scrolled.
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DATE: [10-29-2017 11:29:16] <29 Oct 2017 20:29:16 +0200>
FROM: Eli Zaretskii <eliz@gnu.org>
>
> > Date: Sun, 29 Oct 2017 10:29:29 -0700
> > From: Keith David Bershatsky <esq@lawlist.com>
> > Cc: 29002@debbugs.gnu.org
> >
> > Here is a link to screen-shot #3:
> >
> > https://www.lawlist.com/images/bug_hscl_03.png
> >
> > In that screen-shot, we make the following observations:
> >
> > * A total of 5 screen lines.
> >
> > * Line 1 is the current line.
> >
> > * All 5 lines visually appear to be horizontally scrolled.
> >
> > * Using the revised function bug-hscroll (below), we iterate over each
> > screen line and generate the values for it.first_visible_x and it.vpos.
> >
> > * it.first_visible_x returns as being 0 for each of the 5 screen lines.
>
> This cannot be true: if every line in the window is hscrolled,
> first_visible_x must be non-zero, right after the call to
> start_display. If first_visible_x is zero, only the current line can
> be hscrolled.
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/25
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/25
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/26
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/26
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/29
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling.,
Keith David Bershatsky <=
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/29
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/29
- bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling., Keith David Bershatsky, 2017/10/30