[R] Flickering when scrolling in R graphics windows

[Ziyun Tang]

On Tue, Jan 24, 2023 at 4:50 AM Martin Maechler
<maechler using stat.math.ethz.ch> wrote:
>
> >>>>> Ziyun Tang
> >>>>>     on Sat, 21 Jan 2023 15:14:15 -0500 writes:
>
>     > Hello, I have been experiencing some issues regarding scrolling with
>     > the mouse or trackpad in R graphics windows (from the base graphics
>     > package), which sometimes results in flickering, and wanted to see if
>     > anyone else had the same issues, or any advice. This happens for R
>     > version 4.2.2 on Windows 10 x64, and occurs when using Rgui and at the
>     > command line (whenever graphics windows are invoked). Note that some
>     > of the example code below can cause flickering and can be an issue for
>     > those with photosensitive epilepsy.
>
>     > Specifically, I have been experiencing three main issues, as follows:
>
>     > 1. When viewing a dataset with View(), the graphics window flickers
>     > when scrolling downwards too quickly, even with the option
>     > buffered=TRUE. For example:
>     >> View(iris)
>
> If you use [Page Up]  and [Page Down]  there is no "flickering",
> also using the cursor (up/down "arrows").
> Still here, I would not think anything to be "wrong".
> If you tell the computer to refresh a screen more quickly than
> makes sense I guess you must expect what you see here.
> (but yes, more modern GUIs would do 'smooth scrolling' here; I
>  think that's not available for the graphapp GUI in R for Windows)
>
> By "scrolling", what exactly do you mean?
> Is it that you use your mouse "wheel"? ...  I assume "yes" in
> the following, because in that case I can partly reproduce what
> you describe.

I am seeing that [Page Up], [Page Down] and the cursor still seem to
have some flickering when pressed continuously. And yes, by
"scrolling" I mean with the mouse wheel, and also with two-finger
scrolling via the trackpad, and for the first issue, with the
scrollbar.

>     > 2. When viewing a graph with plot(), and scrolling down, the graphics
>     > window flickers between the background and the graph itself. For
>     > example:
>     >> plot(iris$Sepal.Length, iris$Sepal.Width)
>
> At first I wrote
>    I don't understand how you can "scroll down" in this plot
>
> but now that I've guessed you mean "mouse wheel scrolling" I can
> indeed see what you describe.
>
>     > 3. When viewing a matrix of scatterplots with pairs(), and scrolling
>     > down, the graphics window flickers between the background and the
>     > individual scatterplots. In some instances, when scrolling down with
>     > the trackpad, the window flickers continuously, and subsequently
>     > closing the window crashes R. For example:
>     >> pairs(iris[1:4])
>
> That you bring R to crash just by "scrolling" really seems a bad
> thing and points to a bug.
> OTOH, I have not been able to replicate a crash.

I have retried the example code, and I've found that usually the
flickering/updating eventually settles on one panel of the matrix.
However, when the panel plots are continuously updating, and if the
plot window is closed before it has settled, then R will crash.

> I don't know what mouse-wheel-scrolling should do in a graphics window
> in R for Windows.
> In our terminal server version of Windows,
> using Rterm (via ESS = Emacs Speaks Statistics), I can indeed
> see that  mouse-scrolling in a graphics window has *very funny*
> / strange effects when using the default interactive graphics
> device ( .Device == "windows" ) :
>
> Notably, after say   pairs(iris)    mouse-wheel-scrolling
> "kind of" redraws some of the panel plots mostly in full size
> (instead of the size they were as panels and as part of the full
> "pairs" i.e., scatter plot matrix.
>
> If instead I use RStudio and their own device "RD<something>"
> mouse-wheel-scrolling has no effect, e.g., after  pairs(iris).
> And "no effect" is clearly better than what we observe with the R
> default device "windows" i.e., windows() in the above situation.

>     > My sessionInfo() is as follows:
>
>     > R version 4.2.2 (2022-10-31 ucrt)
>     > Platform: x86_64-w64-mingw32/x64 (64-bit)
>     > Running under: Windows 10 x64 (build 19044)
>
>     > Matrix products: default
>
>     > locale:
>     > [1] LC_COLLATE=English_United States.utf8
>     > [2] LC_CTYPE=English_United States.utf8
>     > [3] LC_MONETARY=English_United States.utf8
>     > [4] LC_NUMERIC=C
>     > [5] LC_TIME=English_United States.utf8
>
>     > attached base packages:
>     > [1] stats     graphics  grDevices utils     datasets  methods   base
>
>     > loaded via a namespace (and not attached):
>     > [1] compiler_4.2.2 tools_4.2.2
>
>     > Thank you in advance,
>     > Ziyun

I'm unsure how to identify the device used by RStudio, but when
viewing RStudio plots in the "Plots" tab I have also seen that
mouse-wheel-scrolling and trackpad-scrolling have no effect for
pairs(iris).