[Tuxpaint-devel] Display bugs in SDL 1.2 (master branch) Tux Paint under X-Window?

[Bill K. <nb...@so...>]

Karl posted these two bugs over on SourceForge:

 * Two directional brushes don't work when using black colour
   https://sourceforge.net/p/tuxpaint/bugs/253/

 * Tux Paint window don��t refresh when alt-tabbed into
   https://sourceforge.net/p/tuxpaint/bugs/254/

I am unable to reproduce either bug on my Ubuntu 20.04.4 LTS
system running Tux Paint 'master' branch with SDL 1.2.15, or
'sdl2.0' branch with SDL 2.0.10, under X-Window X.Org 1.20.13.

Karl reports that the Alt+Tab issue happens with X11 and SDL 1.2.50,
but not under Wayland, nor under SDL 2.0.


The SDL 2.0 version of Tux Paint does not exhibit the brush-drawing
issue Karl reported.

The brushes in question are rotating ones, so I thought perhaps it
was an issue of the brush not wanting to draw anything on a simple
click+release, at least under larger brush spacing, as the brushes
want to know what direction to "face", based on mouse motion.
However, Karl confirms the issue happens all the time, and even
with the Lines tool (not just the Paint [brush] tool).

Since they are rotating, they use some SDL and SDL_gfx routines
to manage rotation (rotozoom).


Based on my inability to reproduce under either SDL 1.2.15 or
SDL 2.0.10 under X11, and Karl only reproducing the issues under
SDL 1.2.50 (and one of the confirmed to happen only under X),
my _hunch_ is there may be some bug in some versions of SDL 1.2,
and/or Tux Paint is doing something naively that causes the
problems to occur (especially with regards to the brush issue).

Can others here please let us know if you come across either
issue, and report back what version(s) of Tux Paint & SDL you're
using.  You can run "tuxpaint --verbose-version" for that.

And let us know whether you're seeing the issues on X-Window and/or
Wayland, and what version(s) of those you're using.

(I've admittedly not used Wayland yet; for X-Window, I run
"xdpyinfo | grep version" to get its version info.)

Thanks in advance!

-- 
-bill!
Sent from my computer