[R] dev.size() does not return correct size on 4K screen

Martijn Tennekes mtenneke@ @end|ng |rom gm@||@com
Thu Mar 3 11:03:44 CET 2022

Thank you, Peter!

 From xdpyinfo I got

screen #0:
   dimensions:    5120x2880 pixels (903x508 millimeters)
   resolution:    144x144 dots per inch

According to these specs my screen should have a sqrt((5120/144)^2 + 
(2880/144)^2) = 40.8" diagonal.

However, in practice it is 27", so that perfectly explains the 1.5 
factor difference.

In RStudio, dev.size() is not equal to par("fin"), which caused the 
problem for me. I the R terminal, these two are equal. I'll post this in 
the RStudio issue list.



On 3/2/22 23:11, peter dalgaard wrote:
> I don't know about RStudio, but in X11 this sort of thing can happen due to misconfiguration of the display itself, i.e. not in R as such. Basically, it relies on getting the correct dots-per-inch value from the display, and may otherwise use some standard value.
> What happens if you run xdpyinfo in a terminal window?
> With XQuartz on an MB Air, I see
> ...
> screen #0:
>    dimensions:    1440x876 pixels (381x232 millimeters)
>    resolution:    96x96 dots per inch
> ...
> which is a multi-way lie! It is a 2560x1600 retina display, the resolution is way higher than 96x96, and it is 13.3", whereas the stated dimensions corresponds to a 17" diagonal.
> However, systems may be "lying in the users best interest", since e.g. the default for an X11() plot window is 7in square, which might not fit on a small laptop. You are somewhat more likely to want the same relative size across different laptops.
> - pd
>> On 2 Mar 2022, at 10:52 , Martijn Tennekes <mtennekes using gmail.com> wrote:
>> dev.size() does not return the correct screen size when using a 4K
>> screen. With the R console and a x11() device, it seems to overestimate
>> with factor 1.5, and in RStudio underestimate with factor 2.
>> See also https://github.com/rstudio/rstudio/issues/10723
>> Is this a bug, or is there something I can do?
>> Best,
>> Martijn Tennekes
>> 	[[alternative HTML version deleted]]
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