Re: Display glitch when drawing a resizable window

[Thomas Dickey]

On Wed, Jun 12, 2019 at 01:32:46AM +0200, Ulf Magnusson wrote:
> On Wed, Jun 12, 2019 at 12:19 AM Thomas Dickey <address@hidden> wrote:
> >
> > On Tue, Jun 11, 2019 at 09:14:52PM +0000, magiblot 1 wrote:
> > > Hi,
> > >
> > > I'm working on a terminal application where you can move and resize 
> > > windows with the mouse. This has led me to face the glitch shown in this 
> > > video:
> > >
> > > https://drive.google.com/open?id=1w08Yb8ORwSxiMIDH73Sn6qb66DbN7O2q
> >
> > looks like turbo vision, e.g., http://tvision.sourceforge.net/
> > which I've not looked at for a while.  I recall that it sometimes
> > did its own printf's (outside ncurses).
> >
> > (but I don't see a sample program in this report - that's where I'd start).
> 
> In case it might be related, I sometimes see the line above the bottom
> yellow separator line briefly flash black when scrolling down in this
> interface: 
> https://raw.githubusercontent.com/ulfalizer/Kconfiglib/screenshots/screenshots/menuconfig.gif

It might be.  But without a testable program, I can only guess.

Taking a look at tvision, for instance, that wouldn't be the right
source (because the pastebin examples use UTF-8, and in any case
tvision is not exactly a _curses_ application, but mostly terminfo).

The shorter example doesn't show any problem; the longer is (something)
indexing in a scrolling region (rather than repainting the box)
and painting the fill-character (slow).

To discuss that, I need a simple program that I can run :-)
 
The video doesn't match either of those pastebin examples.

> See _draw_main() in
> https://github.com/ulfalizer/Kconfiglib/blob/master/menuconfig.py. No
> spurious output to stdout that I'm aware of.
> 
> Happens in both xterm and gnome-terminal. It's a meh for this
> application, because it's relatively rare. I could try to record it if
> needed.
> 
> Cheers,
> Ulf

-- 
Thomas E. Dickey <address@hidden>
https://invisible-island.net
ftp://ftp.invisible-island.net

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